Encyclopedia of plastics testing - User contributions [en]

Crack Resistance Curve – Examples

2026-09-07T12:34:50Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Risswiderstandskurve – Beispiele}}
{{PSM_Infobox}}
Crack resistance curve – Examples
__FORCETOC__

==General information==

The [[Toughness|toughness]] of [[Plastics|plastics]] is characterised on the basis of the [[Crack Resistance (R) Curve|crack resistance (R) curve]] concept; where the [[Material & Werkstoff|material]] exhibits elastic-plastic behaviour, the stages of the entire fracture process—crack blunting, stable [[Crack Initiation|crack initiation]], stable [[Crack Propagation|crack propagation]], and, following this, often unstable crack propagation and [[Fracture|fracture]] — can be described.

==R-curve for isotactic polypropylene (PP)==

Using isotactic polypropylene ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: PP) as an example, this paper demonstrates the possibility of characterising structural modifications (see also: [[Microscopic Structure|microscopic structure]]) caused by nucleation in PP materials [1].

To experimentally determine the [[Crack Resistance (R) Curve|crack resistance curves]] as a basis for establishing the [[Fracture Mechanical Testing|fracture mechanics parameters]] of [[Crack Initiation|crack initiation]] and [[Crack Propagation|crack propagation]], the [[Quasi-static Test Methods|quasistatic tensile test]] was employed using [[SENT-Specimen|SENT]] (Single-Edge-Notched Tension) specimens [2–6].

The addition of nucleating agents influences the structure of PP. Semi-crystalline PP is polymorphic, i.e. it can crystallise into the α, β or γ modification depending on the cooling conditions and the nucleation process. The α-modification is characterised by a helical structure in a monoclinic unit cell, which is the thermodynamically most stable form and thus the most common modification. In comparison, the β modification is less ordered and hexagonal, featuring non-parallel, crossed lamellae. The orthorhombic γ modification can be induced under high pressure or by the use of a nucleating agent [7–9]. The crystal modification influences the fundamental mechanical properties due to its different physical and mechanical properties [8, 9]. PP with a predominant β-modification has a lower [[Elastic Modulus|modulus of elasticity]] and [[Yield Stress|yield stress]] at a comparable [[Strain Rate Basics|strain rate]], but increased [[Impact Test|impact strength]], tensile strain at break [7] and higher [[Crack Toughness|crack toughness]] [10] compared with PP with an α-modification. The crystal structure can be influenced, amongst other things, by the addition of nucleating agents or by the cooling rate.

The isotactic PP was blended with an α-nucleating agent (αPP) or a β-nucleating agent (βPP). The plastics were cooled at a rate of 1 K/min (abbreviated as -1) and moulded into sheets (see also [11, 12]). The [[Crack Resistance (R) Curve|crack resistance curves]] (R-curves) of the various [[Plastics|plastics]] were evaluated in accordance with the procedure set out in ESIS TC4 [13].

{|
|<div style="display: block; text-align: center;" width="600" height="500">[[File:Crack_Resistance_Curve_-_Examples_Fig1-1.jpg|400px]]</div>
|-
|<div style="display: block; text-align: center;" width="600" height="500">[[File:Crack_Resistance_Curve_-_Examples_Fig1-2.jpg|550px]]</div>
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{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|(a) R-curves for the plastics PP-1 and αPP-1, and (b) a typical [[Fracture Surface|fracture surface]] of a test specimen showing a metal-blade notch (1), stable crack propagation (2), the damaged zone (3) and the brittle fracture surface (4)
|}

==Effect of nucleation on polypropylene (PP)==

The R-curves for the three PP materials with different nucleation types are shown in '''Fig. 1a'''. At small stable crack extensions, the differences are relatively minor. At higher stable crack extensions, clear differences emerge between the non-nucleated PP-1 and the two nucleated types. For a comparable stable crack extension Δa, the J-values of αPP-1 and βPP-1 are significantly higher, although there is no significant difference between the two nucleated PP types.

This shows that, at a cooling rate of 1 K/min, the resistance of nucleated PP materials to stable [[Crack Propagation|crack propagation]] is higher than that of non-nucleated PP. A typical [[Fracture Surface|fracture surface]] of a PP material is shown in '''Fig. 1b'''. The metal blade notch, the zone of stable crack growth—characterised by a very [[Fracture Mirror|smooth surface]] and a clear boundary with the damage zone—and the residual fracture surface can be seen.

==See also==

* [[Fracture Mechanics|Fracture mechanics]]
* [[Crack Resistance (R) Curve|Crack resistance (R) curve]]
* [[Crack Resistance Curve – Experimental Methods|Crack resistance curve – Experimental methods]]
* [[Crack Resistance Curve – Elastomers Quasistatic|Crack resistance curve – Elastomers quasistatic]]
* [[Tearing Modulus|Tearing modulus]]

==References==

{|
|-valign="top"
|[1]
|Monami, A., Langer, B., [[Grellmann,_Wolfgang|Grellmann, W.]]: Moderne Methoden der Kunststoffprüfung zur Werkstoffentwicklung und Bauteilprüfung. Werkstoffprüfung. Fortschritte in der Werkstoffprüfung für Forschung und Praxis (2016), December 1 and 2, 2016, Neu-Ulm, Proceedings pp. 233–238 (ISBN 978-3-514-00830-4)
|-valign="top"
|[2]
|[https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.], [[Reincke,_Katrin|Reincke, K.]], Monami, A., Kretzschmar, B.: Bruchmechanische Zähigkeitscharakterisierung von schichtsilikatverstärktem Polypropylen. In: [https://de.wikipedia.org/wiki/Michael_Pohl_(Metallurg) Pohl, M.] (Eds.): Konstruktion, Qualitätssicherung und Schadensanalyse. Stahleisen, Düsseldorf (2007), pp. 115−120 (ISBN 978-3-514-00753-6)
|-valign="top"
|[3]
|[https://de.wikipedia.org/wiki/Wolfgang_Grellmann Grellmann, W.], Langer, B., [[Bierögel,_Christian|Bierögel, C.]], Schoßig, M., Mecklenburg, T.: Bruchmechanische Zähigkeitsbewertung nukleierter glasfaserverstärkter Polyolefinwerkstoffe. In: Pohl, M. (Eds.): Konstruktion, Qualitätssicherung und Schadensanalyse, Publishing House Werkstoff-Informationsgesellschaft mbH, Frankfurt (2004) pp. 321−326 (ISBN 3-88355-337-9)
|-valign="top"
|[4]
|Kroll, M., Langer, B., Grellmann, W.: Toughness optimization of elastomer-modified glass-fiber reinforced PA6 materials. Journal of Applied Polymer Science 127 (2013) 57−66 DOI: [https://doi.org/10.1002/app.36853 https://doi.org/10.1002/app.36853]
|-valign="top"
|[5]
|Kroll, M., Langer, B., Schumacher, W., Grellmann, W.: The influence of carbon black batches on the fracture behavior of glass fiber reinforced PA6/PA66 blends. Journal of Applied Polymer Science 116 (2010) 610−618 DOI: [https://doi.org/10.1002/app.31611 https://doi.org/10.1002/app.31611]
|-valign="top"
|[6]
|Langer, B., Bierögel, C., Grellmann, W., Fiebig, J., Aumayr, G.: Material optimization of PP-short glass fibre compounds. In: Grellmann, W., [[Seidler,_Sabine|Seidler, S.]] (Eds.): Deformation and Fracture Behaviour of Polymers. Springer, Berlin, Heidelberg (2001) (ISBN 978-3540412472; see [[AMK-Library]] under A 7)
|-valign="top"
|[7]
|Maier, C., Calafut, T.: Polypropylene – The Definitive User’s Guide and Databook, William Andrew Publishing/Plastics Design Library (1998) (ISBN 978-0-0809-5041-9)
|-valign="top"
|[8]
|Marigo, A., Causin, V., Marega, C., Ferrari, P.: Crystallization of the gamma form in random propylene-ethylene copolymers. Polymer International 53 (2004) 2001−2008; DOI: [https://doi.org/10.1002/pi.1613 https://doi.org/10.1002/pi.1613]
|-valign="top"
|[9]
|Marigo, A., Marega, C., Causin, V., Ferrari, P.: Influence of thermal treatments, molecular weight, and molecular weight distribution on the crystallization of beta-isotactic polypropylene. Journal of Applied Polymer Science 91 (2004) 1008−1012; DOI: [https://doi.org/10.1002/app.13260 https://doi.org/10.1002/app.13260]
|-valign="top"
|[10]
|Raab, M., Kotek, J., Baldrian, J., Grellmann, W.: Übermolekulare Struktur und mechanische Eigenschaften von isotaktischem Polypropylen. In: Grellmann, W., Seidler, S. (Eds.): Deformation und Bruchverhalten von Kunststoffen. Springer Berlin Heidelberg (1998) (ISBN 3-540-63671-4; e-Book: ISBN 978-3-642-58766-5; see [[AMK-Library]] under A 6)
|-valign="top"
|[11]
|Monami, A., Langer, B., Sadlik, J., Kucera, J., Grellmann, W.: Fracture mechanics properties of polymorphic molypropylene. Procedia Materials Science 3 (2014) 276−281; DOI: [https://doi.org/10.1016/j.mspro.2014.06.048 https://doi.org/10.1016/j.mspro.2014.06.048]
|-valign="top"
|[12]
|Androsch, R., Monami, A., Kucera, J.: Effect of an alpha-phase nucleating agent on the crystallization kinetics of a propylene/ethylene random copolymer at largely different supercooling. Journal of Crystal Growth 408 (2014) 91−96; DOI: https://doi.org/10.1016/j.jcrysgro.2014.09.028
|-valign="top"
|[13]
|Hale, G. E., Ramsteiner, F.: A Testing protocol for conducting J-crack growth resistance curve on plastics. In: Moore, D. R., Pavan, A., Williams, J. G. (Eds.): Fracture Mechanics Testing Methods for Polymers Adhesives and Composites, Elsevier, Amsterdam, London, New York, Oxford, Paris, Shannon, Tokyo (2001) 123–157 (ISBN 0-0804-3689-7)
|}

[[Category:Fracture Mechanics]]

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2026-09-07T12:32:52Z

Oluschinski:

Lexicon Polymer Testing & Diagnostics

2026-09-07T12:32:31Z

Oluschinski: Created page with "<big>Informations to Lexikon Polymer Testing & Diagnostics</big> <templatestyles src="Hauptseite/styles.css" />__NOTOC__ <div id="hauptseite"> <div id="spalten"> <div id="l" style="float:left; margin-right: 3em;"> <div id="PSM_Deckblatt>300px Cover page for the Lexicon Polymer Testing & Diagnostics Version 16.0</div> </div> <div id="r" style="float:left;"> '''Editors''' *Grellmann,_Wolfgang|Prof. Dr. rer...."

<big>Informations to Lexikon Polymer Testing & Diagnostics</big>

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<div id="r" style="float:left;">
'''Editors'''

*[[Grellmann,_Wolfgang|Prof. Dr. rer. nat. habil. Wolfgang Grellmann]] 
*[[Bierögel, Christian|Prof. Dr.-Ing. Christian Bierögel]] 
*[[Reincke, Katrin|Prof. Dr.-Ing. habil. Katrin Reincke]] 

'''Authors and coworkers'''

*Prof. Dr.-Ing. Ines Kotter 
*Dr.-Ing. Ralf Lach 
*Dipl.-Ing. Andreas Oluschinski 
*Dr.-Ing. Katja Oßwald 
*Dr.-Ing. Marcus Schoßig 
*Dipl.-Phys. Christian Sirch 
</div>
</div>

==Editorial board==

Please direct any enquiries regarding articles in this online encyclopaedia to the scientific editorial board.

*Lach, Ralf Dr.-Ing. (Vors.) [mailto:ralf.lach@psm-merseburg.de ralf.lach@psm-merseburg.de] 
*Oluschinski, Andreas Dipl.-Ing. [mailto:andreas.oluschinski@psm-merseburg.de andreas.oluschinski@psm-merseburg.de] 
*Sirch, Christian Dipl.-Phys. [mailto:christian.sirch@psm-merseburg.de christian.sirch@psm-merseburg.de] 

==Foreword==

The scientific basis for the Wiki Lexicon of Polymer Testing & Diagnostics is provided by the textbooks and specialist books published by the Merseburg School (see also [[AMK-Library]]) on polymer testing and diagnostics as well as on the technical fracture mechanics of plastics and composite materials with a polymer matrix. These include, among others:
 
'''Polymer Testing'''
 
[[Grellmann,_Wolfgang|Wolfgang Grellmann]] and [[Seidler,_Sabine|Sabine Seidler]] (Eds.) 
1st Edition 2007 
Carl Hanser, Munich, Vienna 
ISBN 978-1-56990-410-7 
ISBN 978-3-446-40900-2 
 
2nd Edition 2013 
Carl Hanser, Munich 
ISBN 978-1-56990-548-7 
 
3rd Edition 2022 
Carl Hanser, Munich 
ISBN 978-1-56990-806-8 
 
With the collaboration of 
[[Altstädt, Volker|Volker Altstädt]], Monika Bauer, [[Bierögel, Christian|Christian Bierögel]], Gert Busse, Klaus Friedrich, Henrick Höninger, Thomas Lüpke, Bernd Michel, [[Radusch, Hans-Joachim|Hans-Joachim Radusch]], Falko Ramsteiner, Andreas Schönhals, Jörg Trempler

Other reference books published by Springer-Verlag on the deformation and fracture behaviour of plastics are:
{|
|-valign="top"
|1.
|[[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): '''Deformation und Bruchverhalten von Kunststoffen'''. Springer, Berlin Heidelberg (1998), (ISBN 3-540-63671-4; e-Book: ISBN 978-3-642-58766-5; see [[AMK-Library]] under A 6)
|-valign="top"
|2.
|Grellmann, W., Seidler, S. (Eds.): '''Deformation and Fracture Behaviour of Polymers'''. Springer, Berlin Heidelberg (2001) (ISBN 978-3540412472; see [[AMK-Library]] under A 7)
|-valign="top"
|3.
|Grellmann, W., [[Reincke,_Katrin|Reincke, K.]]: '''Technical Material Diagnostics – Fracture Mechanics of Filled Elastomer Blends'''. In: Grellmann, W., Heinrich, G., Kaliske, M., Klüppel, M., Schneider, K., Vilgis, T. (Eds.): Fracture Mechanics and Statistical Mechanics of Reinforced Elastomeric Blends. Springer, Berlin Heidelberg (2013), (ISBN 978-3-642-37909-3; see [[AMK-Library]] under A 14)
|-valign="top"
|4.
|Grellmann, W., Seidler, S.: '''Mechanical and Thermomechanical Properties of Polymers'''. Landolt-Börnstein. Volume VIII/6A3, Springer, Berlin (2014), (ISBN 978-3-642-55165-9; see [[AMK-Library]] under A 16)
|-valign="top"
|5.
|Grellmann, W., Langer, B. (Eds.): '''Deformation and Fracture Behavior of Polymer Materials'''. Springer Series in Materials Science 247, Springer, Berlin Heidelberg (2017), (ISBN 978-3-319-41877-3; e-Book: ISBN 978-3-319-41879-7; see [[AMK-Library]] under A 19)
|}

'''Co-authors of the lexicon'''

[[File:FELMI_ZFE.PNG| 100px |thumb |[http://www.felmi-zfe.tugraz.at/ FELMI-ZFE]]]

1. Martin-Luther-University Halle-Wittenberg, Centre of Engineer Sciences, professorship Material Diagnostic/Material Testing (Chair '''[[Grellmann,_Wolfgang|Prof. em. Dr. rer. nat. habil. Wolfgang Grellmann]]''') and the University of Technology Graz, Institute of Electron-Microscopy and Nanoanalytics (FELMI) together with the Centre of Electron-Microscopy (ZFE) Graz (director '''Univ.-Prof. Dr. Gerald Kothleitner''', see: [http://www.felmi-zfe.at www.felmi-zfe.at]) with whom we have a long-standing collaboration in the field of [[Microscopic Structure|morphology]] and [[Micromechanics & Nanomechanics|micromechanics]] of plastics. 
The following terms were edited by '''Dr. Armin Zankel''', FELMI-ZFE Graz:
<ul>
<li>[[Energy Dispersive X-Ray Spectroscopy (EDX)]]</li>
<li>[[In-situ ultramicrotomy]]</li>
<li>[[Microtomy]]</li>
<li>[[Scanning Electron Microscopy]] (SEM)</li>
<li>[[Environmental-SEM (ESEM)]]</li></ul>

2. The Editors of the "Lexicon Polymer Testing & Diagnostics" have asked '''[[Michler,_Goerg_Hannes|Prof. em. Dr. rer. nat. habil. Goerg H. Michler]]''', Martin-Luther-Universiy Halle-Wittenberg, Institute for Physics, professurship "General Material Science", because of his professional competence in the field of morphology and micro-mechanics of polymers, to explain some terms. 
Following his retirement, Prof. Dr. Michler is now Honorary Chairman in [http://www.ipw-merseburg.de Institut für Polymerwerkstoffe e.V.], Associated institute at the University of applied Science Merseburg and also chairmen of the foundation [http://bethge-stiftung.de Heinz-Bethge-Stiftung] in Halle.

The following terms were edited from Prof. Dr. Michler:
* [[Craze-Types]]
* [[Electron Microscopy]]
* [[Polymers & Structure]]
* [[Micromechanics & Nanomechanics]]
* [[Transmission Electron Microscopy]]
* [[In-situ Ultramicrotomy]]
* [[Material Science & Plastics]]

3. The following terms were edited from '''[[Radusch,_Hans-Joachim|Prof. em. Dr.-Ing. habil. Hans-Joachim Radusch]]''', Martin-Luther-University Halle-Wittenberg, Cetre for Engineering Science, Chair "Kunststofftechnik":

* [[Elongational Viscosity]]
* [[Capillary Rheometer]]
* [[Surface Tension and Interfacial Tension]]
* [[Rheometry|Rheometry/Viscosimetry]]
* [[Pourability]]
* [[Rotational Rheometer]]
* [[Melt Mass-Flow Rate]]
* [[Melt Volume-Flow Rate]]
* [[Bulk Density]]
* [[Repose Angle]]
* [[Materials Science]]
* [[Materials Technology & Materials Science]]
* [[Materials Science & University Education in Merseburg-Halle|Materials Science & University Education in Merseburg/Halle]]

4. The following terms were edited from '''Prof. Dr.-Ing. habil. Michael Nase''', University of Applied Science, Hof, [https://www.ibp-hof.de/ Institute for Bio-Polymer Science], Professorship for Polymer Technology:
* [[Adhesive Energy Release Rate]]
* [[Peel Properties of Peel Systems]]
* [[Peeling Process]]
* [[Peel Behaviour – Modelling]]

5. The following terms were edited from '''Prof. Dr.-Ing. Stephan Marzi''', [https://www.thm.de/site/en/ Technical University Mittelhessen], [https://www.thm.de/me/ Department of Mechanical Engineering and Energy Technology], Gießen:
* [[Cohesive Zone Models]]
* [[ODCB or MC-DCB-Specimens]]
* [[Adhesive Joints – Determination of Characteristic Values]]

6. There is a long-standing scientific collaboration between Martin [https://www.uni-halle.de/?lang=en Luther University Halle-Wittenberg] and [https://www.tuwien.at/en/ Vienna University of Technology], which has resulted in numerous specialist books and publications in the fields of [[Polymer Testing|polymer testing]], [[Polymer Diagnostic|polymer diagnostics]] and technical [[Fracture Mechanics|fracture mechanics]] of [[Polymer|polymer]] and [[Composite Materials Testing|composite materials]]. 
The authors of this lexicon thank to Frau '''Prof. Dr. Vasiliki-Maria Archodoulaki''' and '''Dr. Lisa Schardt''', Vienna University of Technology, [https://tiss.tuwien.ac.at/adressbuch/adressbuch/orgeinheit/1673?locale=en Institute for Materials Science and Materials Technology], FG Structural Polymers, for the guest article:
* [[Microplastic & Nanoplastic]]
 
{{Kasten|
'''For literary citations in the lexicon, please use:''' 
Grellmann, W., Bierögel , C. (&dagger;), Reincke, K. (Eds.) Wiki "'''Lexicon Polymer Testing & Diagnostics'''" 2026, Version 16, http://wiki.polymerservice-merseburg.de
}}

Wolfgang Grellmann, Merseburg and Halle

Foreword last modified on January, the 27th, 2026

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<li>[[:Category:Stress Cracking Resistance|Stress Cracking Resistance]]</li>
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|TITEL=Welcome to the PSM Wiki-lexicon "Polymer Testing & Diagnostics"
|INHALT=With this lexicon, we would like to explain important terms from the plastics sector to interested readers and our customers. Originating from a small glossary on the [https://www.psm-merseburg.de PSM homepage], a wiki lexicon has been created over the years that has more than 1,000 visitors a day. As with its big sister wikipedia, this wiki is also alive. New articles are regularly added and existing ones revised.
|NAME=Welcome}}

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|TITEL=Overview pages
|INHALT=
<ul>
<li>[[Fracture Mechanical Testing]]</li>
<li>[[Elastic Modulus]]</li>
<li>[[Instrumented Hardness Testing – Method & Material Parameters]]</li>
<li>[[Hardness]]</li>
<li>[[Polymer Testing]]</li>
<li>[[Polymer Diagnostic]]</li>
<li>[[Ultrasound Testing]]</li>
<li>[[Polymers & Structure]]</li>
<li>[[Specimen]]</li>
<li>[[Tensile Test]]</li>
<li>[[Surface Tension and Interfacial Tension]]</li>
<li>[[Laser Extensometry]]</li>
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<li>[[Content|Content A – Z]]</li>
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|TITEL=Popular articles
|INHALT=
<ul>
<li>[[SHORE Hardness]]</li>
<li>[[Density]]</li>
<li>[[Processing Shrinkage]]</li>
<li>[[Multipurpose Test Specimen ]]</li>
<li>[[Poisson's Ratio]]</li>
<li>[[Compression Test]]</li>
<li>[[Electrical Strength]]</li>
<li>[[Tensile Strength]]</li>
<li>[[Surface Energy]]</li>
<li>[[Vicat Softening Temperature]]</li>
</ul>
|NAME=beliebt}}

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|TITEL=New and revised articles
|INHALT=
<ul>
<li>[[Bio-Plastics]]</li>
<li>[[Bio-Plastics – Impact-Modified]]</li>
<li>[[Differential Scanning Calorimetry (DSC)]]</li>
<li>[[Fatigue Crack Propagation Elastomers]]</li>
<li>[[Glowing Hot-Wire Test]]</li>
<li>[[Instrumented Hardness Testing – Method & Material Parameters]]</li>
<li>[[Instrumented Scratch Testing]]</li>
<li>[[IRHD Hardness]]</li>
<li>[[Melt Mass-Flow Rate]]</li>
<li>[[Thermostability PVC]]</li>
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<li>[[:Category:Acoustic Test Methods_Ultrasonics|Acoustic Test Methods/Ultrasonics]]</li>
<li>[[:Category:Ageing|Ageing]]</li>
<li>[[:Category:Bend Test|Bend Test]]</li>
<li>[[:Category:Colour and Gloss|Colour and Gloss]]</li>
<li>[[:Category:Compression Test|Compression Test]]</li>
<li>[[:Category:Creep Behaviour Plastics|Creep Behaviour Plastics]]</li>
<li>[[:Category:Damage Analysis_Component Failure|Damage Analysis/Component Failure]]</li>
<li>[[:Category:Deformation engl|Deformation]]</li>
<li>[[:Category:Elastomers|Elastomers]]</li>
<li>[[:Category:Electrical and Dielectrical Testing|Electrical and Dielectrical Testing]]</li>
<li>[[:Category:Fatigue|Fatigue]]</li>
<li>[[:Category:Film Testing|Film Testing]]</li>
<li>[[:Category:Fire Behaviour|Fire Behaviour]]</li>
<li>[[:Category:Fracture Mechanics|Fracture Mechanics]]</li>
<li>[[:Category:Hardness|Hardness]]</li>
<li>[[:Category:Hybrid Methods|Hybrid Methods]]</li>
<li>[[:Category:Impact Tests|Impact Tests]]</li>
<li>[[:Category:Implant Testing|Implant Testing]]</li>
<li>[[:Category:Instrumented Impact Test|Instrumented Impact Test]]</li>
<li>[[:Category:Laser Extensometry|Laser Extensometry]]</li>
<li>[[:Category:Light|Light]]</li>
<li>[[:Category:Material Scientists Polymer Scientists|Material Scientists/Polymer Scientists]]</li>
<li>[[:Category:Materials Science_Materials Engineering|Materials Science/Materials Engineering]]</li>
<li>[[:Category:Measurement Testing Technology|Measurement Testing Technology]] (Measurement Data Aquisition)</li>
<li>[[:Category:Morphology and Micromechanics|Morphology and Micromechanics]]</li>
<li>[[:Category:Optical Field Measurement Methods|Optical Field Measurement Methods]]</li>
<li>[[:Category:Peel Test|Peel Test]]</li>
<li>[[:Category:Plastics|Plastics]]</li>
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<li>[[:Category:Stiffness Compliance|Stiffness/Compliance]]</li>
<li>[[:Category:Stress Cracking Resistance|Stress Cracking Resistance]]</li>
<li>[[:Category:Surface Testing Technology|Surface Testing Technology]]</li>
<li>[[:Category:Tensile Test|Tensile Test]]</li>
<li>[[:Category:Thermoanalytical Methods|Thermoanalytical Methods]]</li>
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[[file:Deckblatt_Kunststoffpruefung.jpg]] About the [Lexicon Polymer Testing & Diagnostics]]
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AMK-Library

2026-09-07T12:28:31Z

Oluschinski: Created page with "You can find a current list of all works of the AMK-Library here: *[http://amk-merseburg.de/buechersammlung/ www.amk-merseburg.de]"

You can find a current list of all works of the AMK-Library here:

*[http://amk-merseburg.de/buechersammlung/ www.amk-merseburg.de]

File:S E Pruefkoepfe-3.JPG

2026-09-07T12:27:42Z

Oluschinski:

File:Griffith.jpg

2026-09-07T12:25:17Z

Oluschinski:

File:FELMI ZFE.PNG

2026-09-07T12:24:17Z

Oluschinski:

Permeation

2026-09-07T12:23:23Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Permeation}}
{{PSM_Infobox}}
Permeation
__FORCETOC__

==General==

The driving force behind this process is a pressure or concentration gradient within the single solid. Without the influence of external factors, the substance always moves in the direction of lower concentration or pressure. Permeation takes place in several steps:

# Adsorption: The substance accumulates on the [[Surface|surface]]. This can occur from the gas phase or through direct contact with the liquid or solid substance.
# Absorption: The substance is absorbed.
# Diffusion: This is where the penetration of the [[Material & Werkstoff|material]] at the molecular level begins. The substance penetrates the solid through pores or molecular interstices.
# Desorption: After the molecules have penetrated the solid, they diffuse away from the surface again.

==Examples of the importance of permeation==

* Working with protective gloves in laboratories or production facilities.
* Food packaging should either be completely airtight (sausages, cheese, drinks) or selectively permeable (e.g. for oxygen in fruit).

==Performing permeation measurements==

Films and membranes are tested for permeability using any gases or liquids. Special measuring cells have been developed for this purpose. These cells are usually made of metal, such as stainless steel. When [[Testing|testing]] gases, a test gas is passed through the measuring cell and the amount remaining after passing through is measured by a detector in terms of concentration.

Analogous to the permeation measurement for gases, the so-called water value is determined in membrane technology. It is used to characterise the performance of a liquid filtration unit and is expressed in l/m2 • h • bar.

==See also==

* [[Water Absorption|Water absorption]]
* [[Standard Atmospheres|Standard atmospheres]]
* [[Test Climate|Test climate]]

==Weblinks==

* Wikipedia – The free Encyclopedia: Permeation (https://en.wikipedia.org/wiki/Permeation) (last accessed February 11, 2026)

[[Category:Film Testing]]

Dispersion

2026-09-07T12:22:51Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Dispersion}}
{{PSM_Infobox}}
Dispersion
__FORCETOC__

==General information==

The term dispersion is used in the natural sciences to refer to a variety of meanings in accordance with its Latin origin (Latin: dispergere – to distribute, spread and scatter).

The Wiki-lexicon ‘[[Lexicon Polymer Testing & Diagnostics|Polymer Testing & Diagnostics]]’ contains the terms

* [[Elastomer Dispersion Filler|elastomer dispersion filler]] and
* [[Layer Silicate-reinforced Polymers|layered silicate-reinforced polymers]],

where dispersion is used to describe the type of distribution of [[Particle-filled Thermoplastics#Technically used fillers|filler particles]] in a rubber matrix [1] or in a polymer nanocomposite [2]. The term dispersion is also very often used in connection with the propagation of light

* [[ABBE Refractometer|ABBE refractometer]]
* [[Refraction Index|Refraction index]]
* [[Refraction Light|Refraction light]]]]

and the propagation of sound waves

* [[Reflection Sound Waves|Reflection sound waves]]
* [[Refraction Sound Waves|Refraction sound waves]]
* [[Sound Emission Analysis|Sound emission analysis]]
* [[Sound Emission Testing|Sound emission testing]],

where it specifically refers to frequency dispersion.

==The dispersion of light==

Light dispersion refers to the dependence of a [[Material & Werkstoff|material]]'s [[Refraction Index|refraction index]] on the frequency ''f'' of the light or the wavelength ''λ''. Dispersion is referred to as normal dispersion if the refraction index or refractive index increases with increasing frequency or decreases with increasing wavelength. In the opposite case, i.e. when the refraction index increases with increasing wavelength, dispersion is referred to as abnormal.

In anisotropic materials, the refraction index ''n'' and all related optical characteristics (e.g. birefringence or optical axis angle) depend on the wavelength ''λ'' of the incident light. In [[Plastics|plastics]] and inorganic glasses, the refraction index decreases with increasing wavelength and thus decreasing frequency of the light. When white light passes through a dispersion prism, it is [[Reflection Light|reflected]] and split into the individual wavelengths or colours of the spectrum ('''Fig. 1'''). The different media differ in the size of the deflection angle for the individual colours.

[[File:Dispersion-1.JPG]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Dispersion of white light through a prism: (a) frequency dispersion and (b) wavelengths of the colour spectrum
|}

For characterisation, the ground dispersion GD is determined according to '''Eq. (1)''' for the middle part of the spectrum, whereby the refraction indices nF and nC are measured.

{|
|-
|width="20px"|
|width="500px"|<math>GD=n_{F}-n_{C}\!</math>
|(1)
|}

The selected wavelengths of the Fraunhofer lines F (''λ''F = 486 nm), C (''λ''C = 656 nm) and D (''λ''D = 589 nm) are most easily adjusted using metal interference filters of the corresponding wavelengths or optical monochromators. This makes it easy to determine the ABBE number ''ν'' in the microscope according to '''Eq. (2)'''.

{|
|-
|width="20px"|
|width="500px"|<math>\nu = \frac{n_{D}-1}{n_{F}-n_{C}}</math>
|(2)
|}

The dispersion can be determined using an [[ABBE Refractometer|ABBE refractometer]]. A large ABBE number means low wavelength dependence of the refractive index at normal dispersion and vice versa [3].

==The dispersion of ultrasound==

The spatial and temporal propagation of mechanical waves in elastic media in a frequency range from 1.6·104 Hz to approx. 1012 Hz is referred to as ultrasound. Mechanical or electromechanical sound sources are used to generate ultrasound, of which [[Piezoelectric Force Transducer|piezoelectric oscillators]] are the most widely used.

The phenomena of ultrasonic propagation, [[Ultrasonic Waves Reflection|reflection]], [[Refraction Sound Waves|refraction]] and [[Ultrasonic Birefringence|birefringence]] are comparable to those of light propagation and are subject to the physical laws of geometric optics.

==See also==

* [[Particle-filled Thermoplastics|Particle-filled thermoplastics]]
* [[Elastomers]]
* [[Macrodispersion Degree Elastomers|Macrodispersion degree elastomers]]
* [[Sound Emission Analysis|Sound emission analysis]]
* [[Sound Velocity|Sound velocity]]

==References==

{|
|-valign="top"
|[1]
|[[Reincke,_Katrin|Reincke, K.]]: Elastomere Werkstoffe – Zusammenhang zwischen Mischungsrezeptur, Struktur und mechanischen Eigenschaften sowie dem Deformations- und Bruchverhalten. Habilitation, Martin-Luther-Universität Halle-Wittenberg, Shaker Publishing, Herzogenrath (2016), (ISBN 978-3-8440-4637-3; see [[AMK-Library]] under B 2-2)
|-valign="top"
|[2]
|Monami, A.: Struktur, Exfolierungszustand und Eigenschaften von PA/OMMT-Verbundwerkstoffen. Dissertation, Martin-Luther-Universität Halle-Wittenberg, Mensch & Buch Publishing, Berlin (2014), (ISBN 978-3-86387-402-5; see [[AMK-Library]] under B 1-26)
|-valign="top"
|[3]
|Trempler, J.: Optical Properties. In: [[Grellmann, Wolfgang|Grellmann, W.]], [[Seidler, Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 305/306 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56690-807-5; see [[AMK-Library]] under A 22)
|}

[[Category:Acoustic Test Methods_Ultrasonics]]
[[Category:Light]]

Ball Indentation Hardness

2026-09-07T12:22:17Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Kugeleindruckhärte}}
{{PSM_Infobox}}
Ball indentation hardness
__FORCETOC__

==Fundamentals==

The ball indentation method was introduced to determine the [[Hardness|hardness]] of [[Plastics|plastics]]. The method is based on [[Measure|measuring]] the penetration depth of a steel ball into the surface of a [[Specimen|test specimen]] under the influence of a test load. This test load is applied for a defined period of time after a preload has been applied. The fundamental difficulty with this method is that the indentation depth is not a linear function of the load. This is compensated for by limiting the indentation depth to a value that is small compared to the ball diameter. A uniform indentation depth range of 0.15 mm to 0.35 mm is achieved by applying four test load levels. The following test loads are specified for this purpose: 49 N, 132 N, 358 N, and 961 N. Discontinuities occur at the load transition points from one load level to the next, resulting in different hardness values for each test load.

==Evaluation and calculation of characteristic values==

When evaluating the test, a nearly continuous transition at the junction of two test load levels is achieved by mathematically taking into account the non-strictly linear indentation depth–load function. To determine the [[Hardness|hardness]], the test load is selected which, 30 seconds after application, produces a indentation depth that lies within the aforementioned range of 0.15 to 0.35 mm (gray area in '''Fig. 1''').

[[File:Ball-Indent-Hard_Fig-1.jpg|300px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Area of validity of ball indentation hardness
|}

[[File:Ball-Indent-Hard_Fig-2.jpg|600px]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px" |Test procedure for measuring ball indentation hardness
|}

'''Figure 2''' shows a schematic representation of the test procedure for determining ball indentation hardness. '''Figure 3''' shows different hardness testers from [https://www.zwickroell.com/ ZwickRoell] and [https://www.instron.com/en/?_gl=1*1cibc6t*_up*MQ..*_ga*NzY3ODg5MzI5LjE3ODM1MTU2NDY.*_ga_PX2J9YJ5R7*czE3ODM1MTU2NDYkbzEkZzAkdDE3ODM1MTU2NDYkajYwJGwwJGgw Instron-Wolpert] (see: [[Manufacturer of Material Testing Machines|manufacturer of material testing machines]]).

[[File:Ball-Indent-Hard_Fig-3.jpg|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px" |Examples of hardness testing devices for measuring ball indentation hardness
|}

The following conditions apply to the evaluation:

* If a indentation depth of < 0.15 mm is determined after the test period has elapsed, the test load must be increased!

* If a indentation depth > 0.35 mm is determined after the test time has elapsed, the test load must be reduced!

* If an indentation depth in the range of 0.15–0.35 mm (gray) is determined after the test time has elapsed, the hardness value is determined manually or by the software!

If this condition is met, the [[Hardness|hardness]] is generally calculated using the following equation:

{|
|-
|width="20px"|
|width="500px" | <math>HB\,=\,\frac{F}{\pi \, dh}</math>            (N/mm2)
|}

Since the [[Load Framework|load frame]] bends during the test, which can be described by the compliance (see: [[Tensile Test Compliance|tensile test compliance]]), the hardness value must be corrected:

{|
|-
|width="20px"|
|width="500px" | <math>HB\,=\,\frac{F_r}{\pi \, dh_r}</math>            (N/mm2)
|}

{|
|-
|width="20px"| with
|width="500px" | <math>F_r\,=\,\frac{0{,}21}{\left( h-h_r \right) + 0{,}21} \cdot F</math>            (N)
|}

with
{|
|-
|''F''0
|width="15px" |
|preload (N)
|-
|''F''L
|
|test load (N)
|-
|''F''
|
|total load (N)
|-
|''F''r
|
|reduced test load (N)
|-
|''d''
|
|ball diameter d = 5 mm
|-
|''h''
|
|indentation depth (mm)
|-
|''h''r
|
|reduced indentation depth
|}

==Characteristic values for moulding compounds and thermoplastics==

The following '''Table''' lists some [[Material Value|material values]] of ball indentation hardness for various [[Moulding Compound|moulding compounds]] and [[Plastics|plastics]].

{| border="1px" style="border-collapse:collapse"
|+ '''Table 1''': Material values of ball indentation hardness for [[Thermoplastic Material|thermoplastics]] and moulding compounds
!! style="width:150px; background:#DCDCDC" | Product group
!! style="width:150px; background:#DCDCDC" | HB (N/mm2)
!! style="width:150px; background:#DCDCDC" | Product group
!! style="width:150px; background:#DCDCDC" | HB (N/mm2)
|-
!colspan="4" |
|-
!colspan="2" | Curing compounds
!colspan="2" | Thermoplastics, unreinforced
|-
|Phenol resin
|style="text-align:center" | ... 200
|Fluoropolymers
|style="text-align:center" | 30 ... 70
|-
|Urea resin
|style="text-align:center" | ... 150
|Polyacetals
|style="text-align:center" | ... 140
|-
|Melamine resin
|style="text-align:center" | ... 200
|Polyamides
|style="text-align:center" | ... 100
|-
|Polyester resin
|style="text-align:center" | ... 200
|Polycarbonates
|style="text-align:center" | ... 100
|-
|Epoxy resin
|style="text-align:center" | ... 200
|Polymethyl methacrylates
|style="text-align:center" | ... 200
|-
|
|
|Polyethylenes
|style="text-align:center" | 10 ... 65
|-
|
|
|Polypropylenes
|style="text-align:center" | 60 ... 75
|-
|
|
|Polystyrenes
|style="text-align:center" | ... 120
|-
|
|
| Polyvinyl chlorides
|style="text-align:center" | ... 120
|-
|
|
|PVC, impact-resistant
|style="text-align:center" | 30 ... 100
|}

==Influence of orientation==

'''Figure 4''' shows the dependence of ball indentation hardness on the measurement location on a [[Multipurpose Test Specimen|multipurpose test specimen]], i.e., the orientation (see: [[Tensile Test Residual Stresses Orientations|tensile test residual stresses orientations]]), for a polypropylene copolymer.

[[File:Ball-Indent-Hard_Fig-4.jpg|400px]]
{|
|- valign="top"
|width="50px"|'''Fig. 4''':
|width="600px" |Dependence of ball indentation hardness on orientation (measurement location) and storage condition in washing lye at 95 °C for a PP copolymer PPC2)
|}

{|
!width="150px" |
!width="550px" |
|-
|-valign="top"
|'''100 h-storage:''':
|If the PP copolymer is stored in washing lye at 95 °C for 100 hours, the blue curve is obtained. It can be seen that lower hardness is also recorded in the shoulder areas due to the lower [[Tensile Test Residual Stresses Orientations|orientation]]. Compared to the initial values, a reduction in the average [[Hardness|hardness]] level can also be observed as a result of the influence of tempering (reduction of residual stresses).
|}

{|
!width="150px" |
!width="550px" |
|-
|-valign="top"
|'''1,000 h-storage:''':
|If this material is stored for up to 1,000 hours under identical conditions, the red curve for the measurement points 10 mm apart is obtained. It is clear to see that the [[Hardness|hardness]] level has evened out in the shoulder area and the middle plane-parallel section. This effect is caused by the greater mobility of the polymer chains and the resulting deformation and orientation compensation.
|}

==See also==

* [[IRHD Hardness|IRHD hardness]]
* [[Conventional Hardness Testing|Conventional hardness testing]]
* [[Ball or Pin Impression Method|Ball or pin impression method]]

==References==

* ISO 2039-1 (2001-12): Plastics – Determination of Hardness – Part 1: Ball Indentation Method
* [[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 182/183 (ISBN 978-1-56990-806-8; e-Book ISBN 978-1-56990-807-5; see [[AMK-Library]] under A 22)
* Koch, T., [[Bierögel, Christian|Bierögel, C.]], Seidler, S.: Conventional hardness values. In: [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.], Seidler, S.: Mechanical and Thermomechanical Properties of Polymers. Landolt-Börnstein. Volume VIII/6A3, Springer, Berlin (2014) 357–379, (ISBN 978-3-642-55165-9; see [[AMK-Library]] under A 16)

[[Category:Hardness]]

Weld Line

2026-09-07T12:19:46Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Bindenaht}}
{{PSM_Infobox}}
Weld line
__FORCETOC__

==Generally differentiation==

A basic distinction is made between static and dynamic weld lines. Static weld lines are created, for example, during the welding process when joining [[Thermoplastic Material | thermoplastic]] moulded parts. A dynamic weld line is created in a plastic component during the injection moulding process by the confluence of at least two mass flows, e.g. behind cavities, through differences in wall thickness or through several gates of the tool.

==Weld line and flow front==

A weld line is always a potential weak point in the [[Component Testing|component]]. The flow fronts meet perpendicularly due to volume expansion and weld together. The lower the pressure and temperature, the lower the strength of the weld line. Reinforcing fibres orient themselves parallel to the weld line due to the shear acting during the injection moulding process and the flow conditions ('''Fig. 1''' and '''Fig. 3''').

==Notch effect of the weld line in components==

If the melt has already cooled down so much that the melt fronts that meet can no longer be completely welded together, an inhomogeneous structure appears in the weld line area ('''Fig. 2a''') and the weld line can be recognised on the [[Surface|surface]] as a [[Notch Geometry|V-shaped notch]] ('''Fig. 2b''') [1].

If tensile stresses occur in this area, the [[Notch Sensitivity | notch effect]] leads to an increase in stress at the weld line, which then acts as a predetermined breaking point. The design of plastic components should be such that weld lines in the main stress area are avoided.

[[file:Bindenaht1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Light microscope images of micro-sections in the area of the weld line [2], a) component made of PA66-CF, b) component made of PA66-GF 6-CF, b) Part of PA66-GF material
|}

[[file:Bindenaht2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px" |a) [[Polarisation Optical Examination|Polarisation microscope image]] of a thin section, component made of PA6 in the area of the weld line [2], b) reflected light microscope image of a component made of polyoxymethylene (abbreviation: POM) with circular weld lines [3]
|}

[[file:Bindenaht3.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px" |Weld line morphology of long-fibre-reinforced polypropylene (steel fibres), a) light microscope image of a thin section, b) steel fibre network in the weld line area after ashing [4]
|}

==See also==

*[[Fibre Orientation|Fibre orientation]]
*[[Glass Fibre Orientation|Glass fibre orientation]]
*[[Polarisation Optical Examination|Polarisation optical examination]]
*[[C-shaped Test Specimen|C-shaped test specimen]]
*[[Processing Shrinkage|Processing shrinkage]]
*[[Shrink Voids|Shrink voids]]
*[[Sink Mark|Sink mark]]

==References==

{|
|-valign="top"
|[1]
|Myer, E.: Plastic Failure Guide – Cause and Prevention. Carl Hanser, Munich Vienna (1996); (ISBN 978-3-446-15715-6; see [[AMK-Library]] under D 1)
|-valign="top"
|[2]
|VDI 3822 Part 2.1.2 (2024-06): Failure Analysis – Defects of Thermoplastic Products Made of Plastics Caused by Faulty Processing
|-valign="top"
|[3]
|Kurr, F.: Praxishandbuch der Qualitäts- und Schadensanalyse für Kunststoffe. Carl Hanser Munich (2014) (ISBN 978-3-446-43775-3; see [[AMK-Library]] under D 6-2)
|-valign="top"
|[4]
|Roth, S.: Spritzgegossene Abschirmgehäuse aus stahlfasergefüllten Thermoplasten – Materialeigenschaften, Verarbeitung, Gestaltung. Technische Universität Chemnitz, ([https://www.deutsche-digitale-bibliothek.de/item/RWGSATMWKBLPXFYVZKOT77KYTHW2RUID?isThumbnailFiltered=true&query=Spritzgegossene+Abschirmgeh%C3%A4use+aus+stahlfasergef%C3%BCllten+Thermoplasten&rows=20&offset=0&viewType=list&firstHit=RWGSATMWKBLPXFYVZKOT77KYTHW2RUID&lastHit=lasthit&hitNumber=1 Dissertation]) 2007
|}

[[Category:Damage Analysis_Component Failure]]

Water Absorption

2026-09-07T12:19:26Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Wasseraufnahme}}
{{PSM_Infobox}}
Water absorption
__FORCETOC__

==Fundamentals==

Several different effects occur in [[Plastics | plastics]] that are subjected to medial [[Stress | stress]] by water, e.g:

* dimensional changes (swelling) caused by water absorption,
* extraction of water-soluble components and
* changes in various properties.

From a physical point of view, water absorption is a diffusion process.

==Experimental methods==

The methods for determining water absorption are described in ISO 62 [1]:

* Method 1: Determination of water absorption in water at 23 °C
* Method 2: Determination of water absorption in boiling water
* Method 3: Determination of water-soluble components
* Method 4: Determination of water absorption after storage at 50 % relative humidity (see: [[Standard Atmospheres| standard climate]])

According to the standard, exposure to humidity, immersion in water at 23 °C and boiling water can cause completely different [[Materials Testing | material behaviour]]. Immersion in water at 23 °C and storage at 100 % humidity are practically equivalent in terms of their effects [2]. The amount of water absorbed when the equilibrium state is reached can be used to compare different [[Plastics | plastics]]. The carefully controlled, non-equilibrium exposure of test [[Specimen | specimens]] made of plastics with precisely defined dimensions can be used to compare different charges of the same [[Material & Werkstoff | material]] and to determine the diffusion constant of the material to be tested [1].

==Physical-chemical processes==

The possibility of chain cleavage by reaction with water (hydrolysis) exists for [[Plastics | polymers]] that contain ester, amide or similar functional groups in the main chain. Acids and alkalis can act as catalysts here and favour chain cleavage, especially in hot water, which thus represents the reverse reaction of polymer synthesis. Due to their hydrophobic phenyl groups, aromatic polyesters only absorb very few aqueous solvents, so that hydrolysis is only observed at elevated temperatures and generally have good cold water resistance [3].

Physico-chemical processes in connection with hydrolysis can be, for example, the local change in [[Crystallinity | crystallinity]], the release of additives or softening when water is absorbed.

Typical mechanical processes are, for example, the formation of [[Tensile Test Residual Stresses Orientations | residual stresses]] as a result of locally different swelling processes or the abrasive damage of plastic surfaces in the presence of aqueous solutions with high flow rates, e.g. during the transport of liquids or natural weathering.

==Determination of characteristic values==

The principle of the quantitative description of water absorption consists of immersing [[Specimen | test specimens]] in distilled water at 23 °C or in boiling distilled water or exposing them to climates with 50 % relative humidity at specified temperatures and for a specified period of time [1]. The amount of water absorbed is calculated by determining changes in mass using commercially available weighing instruments ([[Error Limit|error limit]] ± 0.1 mg).

The [[Specimen|test specimens]] used are square or round panels, tubular or rod-shaped test specimens or test specimens made of prefabricated profiles, extruded parts, panels and laminates.

The water absorption ''c'' is described as the difference between the mass of the test specimen after immersion ''m''2 (swollen test specimen) and the mass of the test specimen after drying ''m''1 (extracted test specimen)

{|
|-
|width="20px"|
|width="500px" | <math>c\,=\,m_2-m_1 \ \left[mg\right]</math>
|}

or as a relative change in mass as a percentage (%)

{|
|-
|width="20px"|
|width="500px" | <math>c\,=\,\frac{m_2-m_1}{m_1}\cdot 100 \ \left[%\right]</math>
|}

or

{|
|-
|width="20px"|
|width="500px" | <math>c\,=\,\frac{m_2-m_3}{m_1}\cdot 100 \ \left[%\right]</math>
|}
where are:
{|
|-
|''m''1
|width="15px" |
|Mass of the test speciemen after the first drying and before immersion in mg
|-
|''m''2
|
|Mass of the test specimen after immersion in mg
|-
|''m''3
|
|Mass after immersion and final drying in mg

|}

{| border="1px" style="border-collapse:collapse"
|+ '''Tab. 1''': Water absorption of various plastics in cold water [2]
!! style="width:160px; background:#DCDCDC" | Material
!! style="width:220px; background:#DCDCDC" | Water absorption after 4 d (mg)
|-
|CA
|style="text-align:center" | 100–250
|-
|PA
|style="text-align:center" | 50–800
|-
|PC
|style="text-align:center" | 5–10
|-
|PE
|style="text-align:center" | ca. 0
|-
|PF , Typ 31
|style="text-align:center" | 100–180
|-
|PF, filler free
|style="text-align:center" | 10–20
|-
|PMMA
|style="text-align:center" | 30–40
|-
|POM
|style="text-align:center" | 20
|-
|PS
|style="text-align:center" | 2–5
|-
|PVC-copolymerisate
|style="text-align:center" | 5–20
|-
|UF, Typ 131
|style="text-align:center" | 200–300
|-
|Vulkanized fibre
|style="text-align:center" | 1500
|}

==See also==

* [[Ageing]]
* [[Standard Atmospheres|Standard atmospheres]]
* [[Test Climate|Test climate]]
* [[Plastography]]
* [[Moulding Compound Test|Moulding compound test]]

==References==

{|
|-valign="top"
|[1]
|ISO 62 (2008-02): Plastics – Determination of Water Absorption
|-valign="top"
|[2]
|Stoeckhert, K., Woebcken, W. (Eds.): Kunststoff-Lexikon. Carl Hanser Munich Vienna (1998), 9th Edition, p. 605, (ISBN 3-446-17969-0) (see [[AMK-Library]] under G 3)
|-valign="top"
|[3]
|Franck, A.: Kunststoff-Kompendium. Vogel Buchverlag, Würzburg (2000) 5th Edition, p. 258 (ISBN 3-8023-1855-2)
|}

[[Category:Specimen Preparation]]

Vulcanization

2026-09-07T12:18:51Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Vulkanisation}}
{{PSM_Infobox}}
Vulcanization process
__FORCETOC__

==General basics==

Rubber compounds can be made up of a variety of components. In addition to the rubber, [[Elastomer Dispersion Filler|filler]], processing aid, plasticizer and other additives, a cross-linking system is mixed in, depending on the [[Polymer|polymer]]. For example, sulphur cross-linking is the preferred method for [[Cross-Linking Elastomers|cross-linking]] diene rubbers (NBR, SBR, NR or BR). In addition to accelerator and activator (see '''Table 1'''), elemental sulphur, which is present in the form of S8-rings, is often used for this purpose. The amount of sulphur required depends on the amount of vulcanization accelerator and the required vulcanizate properties. The use of sulphur donors releases sulphur during vulcanization. Some sulphur donors are also vulcanisation accelerators and are then also dosed in larger quantities. This combination results in synergistic effects, through which the potential cross-linking possibilities of the sulphur donors are fully utilised. In order for the vulcanizate to achieve the properties relevant to the application, an accelerator must be mixed in alongside the sulphur. Almost all accelerators are only fully effective in the presence of metal oxides, of which zinc oxide (ZnO) has proven to be the best additive. The rubber/sulphur/accelerator/zinc oxide system is additionally activated by the addition of stearic acid or zinc stearate. This increases the solubility of the cross-linking system in the rubber by forming soluble complexes. Vulcanization retarders are used when vulcanization times are too short or high processing temperatures are required. This ensures sufficient processing safety [1].

{|
|- valign="top"
|width="650px"|'''Table 1''': Possible structure of a networking system [1]
|}
[[file:Vulcanisation_Tab1.jpg]]

==Models for the vulcanization process==

There are several theories in the literature as to how vulcanization takes place chemically. The idea of Morrison and Porter [2] is listed in the literature as the most probable. According to this theory, an active accelerator complex is formed during [[Cross-Linking Elastomers|cross-linking]], which determines the duration of the incubation time. It is also certain that in the presence of zinc ions, complexes are formed that are soluble in the rubber. The active accelerator complex reacts with the sulphur and forms a sulphur transfer complex. The sulphur is then transferred to the rubber and finally cross-linking takes place. In addition to this simple reaction process, a series of subsequent and parallel reactions take place, which have different activation energies [3].

The incorporation of sulphur into the network during vulcanization can take place as a monosulphidic, disulphidic, polysulphidic, pendant sulphidic or cyclic monosulphidic and disulphidic grouping, which can be incorporated into the polymer matrix with the formation of pendant groups (SyR) (see '''Fig. 1'''). In addition to polysulphide degradation in the cross-linking sites, the subsequent reaction of cross-linking is the formation of cyclic thioethers on the rubber chain and zinc sulphide formation (from ZnO and polysulphidic sulphur). The mono- and disulphide structures result in lower permanent deformation, better thermal [[Durability Elastomers|durability]] and lower reversion behaviour. In contrast, polysulphide cross-links can migrate along the chain at elevated temperatures, whereby there is no chain scission (slipping effect) and local stress peaks are reduced. The sulphur attacks the double bond in the polymer chain in the a-position (-C=C-C*-, *S-attack in the ally position). The cross-linking sites are approx. 30 to 100 monomer units apart [4].

[[file:Vulcanisation_1.jpg|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="650px"|Sulphur structures in the rubber network [4]
|}

==Determination of the vulcanization process with the aid of vulcametry==

In practice, vulcametry is often used to determine the course of the cross-linking reaction, which is based on the proportionality between the shear modulus and the [[Degree of Cross-Linking Elastomers|cross-linking density]] (see also: [[Entropy Elasticity | entropy elasticity]]). Vulcameters consist of a temperature-controlled reaction chamber and a force or torque measuring device. According to DIN 53529-1, the test can be carried out with different types of equipment [5]. When testing with a torsional shear vulcameter without a rotor, the specimen is subjected to an oscillating (sinusoidal) deformation of the specimen chamber. The periodic change in shear force or torque is recorded as a function of time. The course of the cross-linking reaction is shown schematically in '''Figure 2'''. The minimum value (''F''a) of the cross-linking isotherms corresponds to the deformation resistance of the uncross-linked specimen.

[[file:Vulcanisation_2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="650px"|Cross-linking isotherm of a rubber compound according to DIN 53529-2 [6]
|}

In the majority of cross-linking systems, the cross-linking reaction does not start immediately, but with a time delay. This period is known as the incubation time (''t''i) and depends on the heating time of the sample as well as the upstream chemical reaction. In the case of sulphur cross-linking, for example, the incubation time is based on the delayed formation of the active accelerator complex.

Once the cross-linking reaction is complete, the vulcameter curve reaches a final value (''F''∞), which corresponds to the crosslinking density. The conversion of the cross-linking reaction in a rubber compound can be calculated by determining the conversion variable ''x'', after the conversion time ''t''x, according to equation (1).

{|
|-
|width="20px"|
|width="500px" | <math> X = \frac{F_{t} - F_{a}}{F_{\infty} - F_{a}}</math>
|(1)
|}

==See also==

* [[Goodyear, Charles Nelson]]
* [[Degree of Cross-Linking Elastomers]]
* [[Rebound Resilience Elastomers|Rebound resilience elastomers]]
* [[Instrumented Tensile Impact Test (ITIT), Examples|Instrumented tensile impact test (ITIT), examples]]
* [[Dielectric Properties|Dielectric properties]]
* [[Curing]]

==References==

{|
|-valign="top"
|[1]
|[https://de.wikipedia.org/wiki/Peter_Elsner Elsner, P.], [https://de.wikipedia.org/wiki/Peter_Eyerer Eyerer, P.], Hirth, T. (Eds.): Kunststoffe Eigenschaften und Anwendungen. 8th revised and extended Edition, Springer Heidelberg (2012) (ISBN 978-3-642-16172-8; see [[AMK-Library]] under G 41)
|-valign="top"
|[2]
|Morrison, N. J., Porter, M.: Temperature Effects on the Stability of Intermedicates and Crosslinks in Sulfur Vulcanization. Rubber Chem. Technol. 57 (1984) 63–85; https://doi.org/10.5254/1.3536002
|-valign="top"
|[3]
|Röthemeyer, F., Sommer, F.: Kautschuk Technologie. 2nd revised Edition, Carl Hanser Munich Vienna (2006) (ISBN 978-3-446-40480-9)
|-valign="top"
|[4]
|Schnetger, J.: Lexikon Kautschuktechnik. 3rd Edition, Hüthig Heidelberg (2004) (ISBN 978-3-7785-3022-1; see AMK-Library under K 7)
|-valign="top"
|[5]
|DIN 53529-1 (1983): Testing of Rubber and Elastomers – Measurement of Vulcanization Characteristics (Curometry) – General Working Principles
|-valign="top"
|[6]
|DIN 53529-2 (1983): Testing of Rubber and Elastomers – Measurement of Vulcanization Characteristics (Curometry) – Evaluation of Cross-linking Isotherms in Terms of Reaction Kinetics
|}

[[Category:Elastomers]]

Volume Swelling Elastomers

2026-09-07T12:18:34Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Volumenquellung Elastomere}}
{{PSM_Infobox}}
Volume Swelling Elastomers
__FORCETOC__

==General information==

The volume change of elastomers and thermoplastic elastomers refers to the processes of volume swelling and volume [[Processing Shrinkage | shrinkage]], which cause an increase or decrease in volume.

The volume change of elastomers and thermoplastic elastomers as a reaction to liquids/media (e.g. oils or greases) represents a quantifiable indicator for characterizing the chemical resistance to media. A media-chemically induced attack on the macromolecular structure and the additives used often leads to a change in the physical-mechanical properties or the use properties. The type of [[Material & Werkstoff | material]] (see also: [[Polymers & Structure | Polymer & structure]]), the acting medium, their mutual compatibility as well as the media exposure time and the temperature influence the migration behaviour of liquids into the elastomer material.

Depending on the chemical resistance/solubility to liquids/media, volume changes occur in the following forms:

* Volume swelling/increase
* Volume shrinkage/[[Processing Shrinkage | processing shrinkage]]/decrease
* complete material decomposition (chemically induced decomposition of the cross-linking structure (link to cross-linking elastomers))

Volume swelling is when the medium acts as a kind of solvent, penetrates the macromolecular structure and is deposited there, resulting in an increase in volume compared to the initial state.

Volume shrinkage, on the other hand, is characterized by the extraction of soluble additives/components and an associated decrease in volume.

==Determination of volume swelling elastomers==

Depending on the area of application of the elastomer materials, it is necessary to know the compatibility with media such as greases, oils or fuels so that damage due to a change in volume can be avoided.

The volume change of an elastomer material in a liquid/medium can be determined in accordance with ISO 1817 [1]. The test liquid must be at least 15 times the total volume of the completely immersed samples. The immersion time of the elastomer material in the liquid/medium is usually not limited to a predetermined end time and should instead be extended beyond reaching the absorption maximum. Within the framework of control tests and the empirical values already obtained in preliminary tests, a single immersion time can be selected in which the absorption maximum is reached.

To determine the volume change, the masses are determined before and after immersion in a liquid/medium, whereby the weighings are carried out in air and in deionized water, but also alternatively in a test liquid. This procedure corresponds to the determination of [[Density | density]] using the immersion method (buoyancy method). The balance used for weighing must not exceed a maximum measurement uncertainty of 1 mg.

If the masses are weighed in deionized water, the percentage change in volume is calculated according to equation (1).

{|
|-
|width="20px"|
|width="500px" | <math> \Delta V_{100} = \left( \frac {m_i - m_{i,m} + m_{s,w}} {m_0 - m_{0,w} + m_{s,w}} \right) </math>
|(1)
|}

where
{|
|-
|Δ ''V''100
|width="15px" |
|is the percentage change in volume; 
|-
|''m''0
|
|is the initial mass of the sample; 
|-
|''m''i
|
|is the mass of the sample after immersion; 
|-
|''m''0,w
|
|is the initial mass of the sample in water (with additional weight, if used); 
|-
|''m''i,w
|
|is the mass of the sample after immersion in water (with additional weight, if used); 
|-
|''m''s,w
|
|is the mass of the additional weight in water, if used.
|}

If, on the other hand, the masses are weighed in the test liquid used, the percentage change in volume is calculated according to equation (2).

{|
|-
|width="20px"|
|width="500px" | <math> \Delta V_{100} = \left(\frac {m_i - m_{i,liq} + m_{s,liq}} {m_0 - m_{0,w} + m_{s,w}} \right) </math>
|(2)
|}

where
{|
|-
|''m''0
|
|is the density of the liquid 
|-
|''m''i
|
|is the mass of the sample after immersion; 
|-
|''m''i,liq
|
| is the mass of the sample (with additional weight, if used) in the liquid; 
|-
|''m''s,liq
|
| is the mass of the additional weight in the liquid, if used.
|}

The minimum number of 3 samples per test series used to determine the volume change in accordance with the standard should have the same initial thickness (2 mm ± 0.2 mm) and a volume of 1 cm³ to 3 cm³, whereby the time interval between vulcanization and testing must be at least 16 hours, but must not exceed 3 months in the case of product testing.

The result of the percentage volume change is given as a median value for at least three test samples.

==Explanation of terms==

The term ‘test piece’ is used in the standard for determining the change in volume, whereas the term ‘sample’ is used without exception in the context of this lexicon in plastics analysis in contrast to the term ‘[[Specimen | test specimen]]’. The use of the term ‘test piece’ is limited to the reproduction of the titles of the standards.

==See also==

* [[Ageing Elastomers | Ageing elastomers]]
* [[Thermosets]]
* [[Density]]
* [[Degree of Cross-Linking Elastomers | Degree of cross-linking elastomers]]
* [[Vulcanization]]

==References==

{|
|-valign="top"
|[1]
|ISO 1817 (2024-03): Rubber, Vulcanized or Thermoplastic – Determination of the Effect of Liquids
|}

'''Standards information'''

* ISO 23529 (2016-11): Rubber – General Procedures for Preparing and Conditioning Test Pieces for Physical Test Methods
* ISO 175 (2010-10): Plastics – Methods of Tests for the Determination of the Effects of Immersion in Liquid Chemicals
* ISO 13226 (2018-06): Rubber – Standard Reference Elastomers (SREs) for Characterizing the Effect of Liquids on Vulcanized Rubbers

[[Category:Elastomers]]

Volume Resistance

2026-09-07T12:18:15Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Durchgangswiderstand}}
{{PSM_Infobox}}
Volume resistance
__FORCETOC__

==Definition of the volume resistance==

The volume resistance is defined as the quotient of an electrical voltage applied between two electrodes and the current intensity measured between these electrodes.

Two ring-shaped plate electrodes are applied to the test specimen, which consists of a [[Plastics | plastic]] or [[Elastomers|elastomer]] and whose contact surfaces must be flat and plane-parallel. However, other geometries are also possible (e.g. cylindrical electrodes). At a given voltage ''U'', the value of which must be below the [[Electrical Strength | electrical strength]] in relation to the distance between the electrodes, and a constant current ''I'', the resistance value is determined. The current along the [[Surface|surface]] is not taken into account, and possible polarisation phenomena at the electrodes are neglected.

==Measurement setup for determining the volume resistance==

The volume resistance is determined according to the measuring set-up in '''Fig. 1'''. Here, ''U'' is the operating voltage and ''R''V is a variable resistor with which the measuring voltage ''U''V at the two electrodes of the measuring capacitor, in which the dielectric to be tested is located, can be set.

[[file:Volume Resistance 1.jpg|500px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Principle circuit diagram for measuring the volume resistance
|}

To prevent deformation of the electric field between the electrodes and to avoid the measurement errors caused by this, the anode (lower electrode in Fig. 1) is divided into a ring electrode, which is placed on the potential of the cathode, and a measuring electrode, with a gap of 5 mm between these two electrodes to prevent voltage flashovers according to DIN IEC 60093.

Typical [[Plastics | plastics]] for testing the volume resistance are insulating materials such as polyethylene ([[Plastics – Symbols and Abbreviated Terms | abbreviation]]: PE), polyvinyl chloride ([[Plastics – Symbols and Abbreviated Terms | abbreviation]]: PVC), polyester ([[Plastics – Symbols and Abbreviated Terms | abbreviation]]: PES), polytetraflourethylene ([[Plastics – Symbols and Abbreviated Terms | abbreviation]]: PTFE or Teflon) and elastomers.

The electrical [[Material Value|values]] of volume resistance and [[Electrical Strength | electrical strength]] are determined with a high-impedance resistance measuring device with connected measuring capacitor or with a electric strength tester.

==See also==

* [[Electrical Strength|Electrical strength]]
* [[Dielectric Properties|Dielectric properties]]
* [[Dielectric Loss Factor|Dielectric loss factor]]

==References==

* Hellerich, W., Harsch, G., Haenle, S.: Werkstoffführer Kunststoffe: Eigenschaften, Prüfungen, Kennwerte. Carl Hanser Munich Vienna (2004) (ISBN 978-3-446-22559-6)
* DIN IEC 60093 (1993-12): Methods of Test for Insulating Materials for Electrical Purposes; Volume Resitivity and Surface Resistivity of Solid Electrical Insulating Materials (IEC 60093:1980), German Version HD 429 S1:1983 (withdrawn; replaced by DIN EN IEC 62631-3-1 (2023-10))
* DIN EN IEC 62631-3-1 (2023-10): Dielectric and Resistive Properties of Solid Insulating Matrials – Part 3-1: Determination of Resistive Properties (DC methods) – Volume Resistance and Volume Resistivity – General Method (identical with VDE 0307-3-1:2023-10)
* Schönhals, A.: Electrical and Dielectrical Properties. In: [[Grellmann, Wolfgang|Grellmann, W.]], [[Seidler, Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 330–368 (ISBN 978-1-56990-806-8; see [[AMK-Library]] under A 22)

'''Additional References'''

* Dhakal, K. N., [https://researchgate.net/profile/Ralf-Lach Lach, R.], [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.], Krause, B., Piontek, J., Adhikari, R.: Piezoresitivity and strain-sensing behavior of poly (butylene adipate-co-terephthalate)/multiwalled carbon nanotube nanocomposites. Royal Society of Chemistry. RSC Advances (RSC Adv.) 14 (2024) 35715–35726 DOI: [https://doi.org/10.1039/D4RA04826A https://doi.org/10.1039/D4RA04826A]

[[category:Electrical and Dielectrical Testing]]

File:Vickers Hardness.jpg

2026-09-07T12:17:49Z

Oluschinski:

Vickers Hardness

2026-09-07T12:17:29Z

Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Vickers-Härte}} {{PSM_Infobox}} Vickers hardness __FORCETOC__ ==General information== The Vickers hardness testing method (named after the English company Vickers) was developed in 1925 by Smith and Sandland. The decisive factor was that the applicability of Brinell hardness was limited due to the flattening of the steel ball, and carbide balls were not yet available at that time...."

{{Language_sel|LANG=ger|ARTIKEL=Vickers-Härte}}
{{PSM_Infobox}}
Vickers hardness
__FORCETOC__

==General information==

The Vickers hardness testing method (named after the English company Vickers) was developed in 1925 by Smith and Sandland. The decisive factor was that the applicability of Brinell hardness was limited due to the flattening of the steel ball, and carbide balls were not yet available at that time.

==Measurement principle of Vickers hardness==

The Vickers method is very similar to the Brinell method. Instead of a ball, a regular, four-sided diamond pyramid with a square base and an angle of 136° between the opposite areas is used as the [[Indenter|indenter]]. The indenter is pressed vertically into the test specimen or sample with a test load ''F'', and the impression is normally measured under a light microscope in the manner illustrated in the image after the load is removed:

[[File:Vickers Hardness.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig.''':
|width="600px" |Schematic illustration of Vickers [[Hardness|hardness]] testing with measurement technology (a), indentation creation (b), and indentation measurement (c)
|}

The test load must be adapted to the respective geometric and morphological conditions; as a rule, tests are performed with loads ≤ 5 N. Normally, the test load ''F'' in the Vickers hardness test is selected so that the indentation diagonal ''d'' is relatively large compared to the structural components (internal averaging) and can thus be measured more [[Measuring Accuracy|accurately]] (lower relative error). However, the [[Hardness|hardness]] of individual structural components can also be measured specifically, in which case the geometric conditions must be selected in exactly the opposite way.

==Definition of Vickers hardness==

The lengths of the two indentation diagonals are determined as the [[Measured Variable|measured variables]]. From this, the average indentation diagonal ''d'' is calculated, which is used to calculate the Vickers hardness HV.

{|
|-
|width="20px"|
|width="500px" | <math>HV\,=\,\frac{F}{A}\,=\,\frac{0{.}1891 \; F}{d^2}</math>
|}

with
{|
|-
|HV
|width="15px" |
|Vickers hardness in N mm-2
|-
|''F''
|
|test load in N
|-
|''A''
|
|Indentation surface in mm2
|-
|''d''
|
|Average value of indentation diagonal in mm
|}

''Comment:''

''In the hardness testing of [[Plastics|plastics]], the physically exact unit of measurement N mm-2 is always specified for the hardness value. When testing the hardness of metallic materials, the test force F is multiplied by 0.102 (≈1/9.80665 = 1/gn) (gn – acceleration due to gravity). The resulting value has the dimension kp. However, since the kp was removed from the hardness designation, this unit is no longer specified; only the hardness value without dimension is given. The kp can still be found as a specification for the test force levels, especially on older hardness testing machines.''

When performing the Vickers test, the resulting indentation is normally measured after unloading, but there are also ways to determine it under load. In this case, the test specimen surface and thus the indentation diagonal are observed through the diamond [[Indenter|indenter]], which allows, for example, real-time conclusions to be drawn about [[Creep Plastics|creep behaviour]].

While the Vickers method is standardized for metallic materials and therefore test load recommendations exist for the micro, small load, and macro ranges, the Vickers method is not standardized for [[Plastics|plastics]].

==Instrumented hardness testing with Vickers indenter==

In [[Hardness#Instrumented hardness testing|instrumented hardness testing]] with Vickers indenters, the entire indentation process is recorded during loading and load–indentation depth diagrams are recorded. Due to the pyramid geometry, the indentation depth ''h'' is related to the indentation diagonal ''d'' by the relationship ''h'' = ''d''/7.0006.

In addition to the hardness value, [[Hardness#Instrumented hardness testing|instrumented hardness testing]] can be used to determine other mechanical [[Material Parameter|material parameters]] such as the modulus of elasticity ([[Indentation Modulus|indentation modulus]]), work hardening exponents, and [[Viscoelastic Material Behaviour|viscoelastic properties]].

==See also==

* [[Conventional Hardness Testing|Conventional hardness testing]]
* [[Ball Indentation Hardness|Ball indentation hardness]]
* [[Scratch Hardness|Scratch hardness]]
* [[TABOR Relationship|TABOR relationship]]
* [[Instrumented Scratch Testing|Instrumented scratch testing]]

==References==

* [[Blumenauer, Horst]] (Ed.): Werkstoffprüfung. Deutscher Verlag für Grundstoffindustrie, Leipzig Stuttgart (1994) 6th Edition, (ISBN 978-3-342-00547-6; see [[AMK-Library]] under M 3)
* [[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Kunststoffprüfung. Carl Hanser, Munich (2022) 3rd Edition, p. 180 (ISBN 978-1-56990-806-8; e-Book ISBN 978-1-56990-807-5; see [[AMK-Library]] under A 22)

[[Category:Hardness]]

Vicat Softening Temperature

2026-09-07T12:17:08Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Vicat-Erweichungstemperatur}}
{{PSM_Infobox}}
Vicat softening temperature
__FORCETOC__

==Methodological basics==

The aim of the VICAT [[Heat Resistance | heat resistance]] method is to quantitatively characterise the heat distortion resistance temperature of a [[Thermoplastic Material | plastic]]. For this purpose, the VICAT heat distortion resistance temperature is determined, which, for methodological reasons, does not have to be quantitatively identical to the heat distortion temperatures determined by other experimental methods (such as the [[Heat Distortion Temperature HDT | heat distortion temperature HDT]]) [1].

The ISO 306 standard [2] specifies four methods for determining the VICAT softening temperature, designated according to the selected test load and heating rate:

''Procedure''

*A 50: with a force of 10 N and a heating rate of 50 °C/h
*A 120: with a force of 10 N and a heating rate of 120 °C/h
*B 50: with a force of 50 N and a heating rate of 50 °C/h
*B 120: with a force of 50 N and a heating rate of 120 °C/h

The temperature in °C at which an indenter tip penetrates 1 mm deep into the surface of the [[Specimen | test specimen]] is determined. The indenter tip has a circular cross-section surface with an area of 1 mm2 . The measured temperature is referred to as the Vicat Softening Temperature VST. Square (base area 10 mm x 10 mm) or round (minimum diameter 10 mm) test specimens with a thickness of 3 mm to 6.5 mm are used for the test. The surfaces must be flat and parallel, as well as burr-free.

==Principle of the VICAT test equipment==

The VICAT test device consists of a rod with a support plate for the test weights and a fixture for the indenter tip, as well as a calibrated dial gauge for determining the indentation depth. The test specimens described are positioned on a test specimen support and heated at a defined heating rate in a silicone bath or with air heating (see '''Figure 1''').

[[file:vicat_messplatz_eng.jpg|400px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Test setup for determination VICAT softening temperature
|}

==Examples of VICAT softening temperatures==

Since the VICAT softening temperature responds to a change in molecular size, the measurement can be used to infer processing-related thermal damage.

{| border="1px" style="border-collapse:collapse"
|+ '''Table''': VICAT softening temperatures for different [[Plastics – Symbols and Abbreviated Terms | plastics]] [3, 4]
!! style="width:250px; background:#DCDCDC" | Material
!colspan="2" style="width:200px; background:#DCDCDC" | VST (°C)
|-
|
|style="text-align:center" | A 50
|style="text-align:center" | B 50
|-
|
|
|
|-
!colspan="3" | '''unreinforced plastics'''
|-
|PE-HD
|
|style="text-align:center" | 75
|-
|PE-LD
|style="text-align:center" | 52
|
|-
|PE-UHMW
|style="text-align:center" | 130
|style="text-align:center" | 74
|-
|PP
|style="text-align:center" | 150
|style="text-align:center" | 90
|-
|POM
|
|style="text-align:center" | 150
|-
|PA 6
|
|style="text-align:center" | 200
|-
|PBT
|
|style="text-align:center" | 190
|-
|PC
|
|style="text-align:center" | 145
|-
|PMMA
|
|style="text-align:center" | 103
|-
|PVC-U
|style="text-align:center" | 83
|style="text-align:center" | 77
|-
|PVC-P
|
|style="text-align:center" | 42
|-
|PS
|
|style="text-align:center" | 84
|-
|SAN
|
|style="text-align:center" | 106
|-
|ABS
|
|style="text-align:center" | 87
|-
|
|
|
|-
!colspan="3" | '''reinforced plastics'''
|-
|PP + 20 M.-% Talkum
|style="text-align:center" | 153
|style="text-align:center" | 95
|-
|PP + 40 M.-% Talkum
|style="text-align:center" | 153
|style="text-align:center" | 98
|}

A comprehensive literature review on the experimental values of Vicat softening temperatures is presented in [5] for ABS, ASA, ECTFE, ETFE, EVA, FEP, HABS, PA6, PA66, PA46, PA610, PA612, PA 11, PA 12, PA1010, PA1, PB-1, PPI, PBT, PC, PCTFE, PE-HD, PE-HMW, PE-LD, PE-UD, PE-MD, PE-UHMW, PE-X, PEEK, PEI, PEK, PESU, PET, PHR, PI, PMMA, PMMI, POM, PP, PPA, PPE, PPS, PPSU, PS, PSU, PTFE, PVC, PVDF, SAN and SB-Copolymers are included. In addition, examples of the dependence of the Vicat softening temperature on filler contents of particles or nanoparticles in various thermoplastics are given.

==See also==

* [[Heat Distortion Temperature HDT | Heat distortion temperature HDT]]
* [[Heat Resistance | Heat resistance]]

==References==

{|
|-valign="top"
|[1]
|[[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser Munich (2022) 3rd Edition (2022) pp. 570–573 (ISBN 978-1-56990-806-8; see [[AMK-Library]] under A 22)
|-valign="top"
|[2]
|ISO 306 (2022-11): Plastics – Thermoplastic Materials – Determination of Vicat Softening Temperature (VST)
|-valign="top"
|[3]
|Carlowitz, B.: Tabellarische Übersicht über die Prüfung von Kunststoffen. Giesel Verlag für Publizität, Isernhagen (1992) (ISBN 978-3980294201; see [[AMK-Library]] under C 9)
|-valign="top"
|[4]
|Campus® Database: http://www.campusplastics.com (access at 02.05.2025)
|-valign="top"
|[5]
|Kotter, I., [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.]: Vicat Softening Temperature and Heat Distortion Temperature. In: [https://de.wikipedia.org/wiki/Wolfgang_Grellmann Grellmann, W.], [[Seidler,_Sabine|Seidler, S.]]: Mechanical and Thermomechanical Properties of Polymers. Landolt-Börnstein. Volume VIII/6A3, Springer Berlin (2014) pp. 62–75, (ISBN 978-3-642-55165-9; see [[AMK-Library]] under A 16)
|}

'''Compilation of Standards'''

* ASTM D 1525 (2025): Standard Test Method for Vicat Softening Temperature of Plastics
* ISO 2507 (1995-02): Thermoplastics Pipes and Fittings – Vicat Softening Temperature –
** Part 1: General Test Method
** Part 2: Test Conditions for Unplasticised Poly(vinyl Chloride) (PVC-U) or Chlorinated Poly(vinyl chloride) (PVC-C) Pipes and Fittings and for High Impact Resistance Poly(vinyl chloride) (PVC-HI) Pipes
** Part 3: Test Conditions for Acrylonitrile/butadiene/styrene (ABS) and Acrylonitrile/styrene/acrylic Ester (ASA) Pipes and Fittings

[[Category:Thermoanalytical Methods]]

File:Schwingungsbruch-6.jpg

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Oluschinski:

File:Vibration Fructure Fig-5.jpg

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File:Schwingungsbruch-4.jpg

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File:Vibration Fructure Fig-3.jpg

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File:Schwingungsbruch-2.jpg

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File:Vibration Fructure Fig-1.jpg

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Oluschinski:

Vibration Fracture

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Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Schwingungsbruch}} {{PSM_Infobox}} Vibration fracture __FORCETOC__ ==General information== Vibration fractures occur during dynamic or vibrating stress on components in practical applications or on test specimens in so-called fatigue tests [1, 2]. Compared to static, quasi-static or ..."

{{Language_sel|LANG=ger|ARTIKEL=Schwingungsbruch}}
{{PSM_Infobox}}
Vibration fracture
__FORCETOC__

==General information==

Vibration fractures occur during dynamic or [[Fatigue|vibrating]] [[Stress|stress]] on [[Plastic Component|components]] in practical applications or on test [[Specimen|specimens]] in so-called [[Fatigue|fatigue]] tests [1, 2]. Compared to static, [[Quasi-static Test Methods|quasi-static]] or [[Impact Loading Plastics|impact stress]], failure under vibrating loads results in [[Fracture Surface|fracture surfaces]] with a different appearance. In general, the fracture surfaces of metallic materials and [[Plastics|plastics]] under dynamic stress have similar fracture surface characteristics (see: [[Fracture Types|types of fracture]]), which are significantly influenced by the [[Ductility Plastics|ductility]] and [[Toughness|toughness]] of the materials under investigation.

However, differences in the fracture patterns of metals and plastics are also caused by the type of fatigue test. While the tensile threshold range and low test frequencies (< 50 Hz) are preferred for plastics due to the thin geometric shape of the components or test specimens, higher frequencies can be used for metals and both the alternating and compressive threshold ranges can be used to characterise the fatigue properties ('''Fig. 1''').

[[File:Vibration_Fructure_Fig-1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Stress areas in continuous vibration testing (fatigue testing)
|}

==Fatigue fractures in plastics==

The starting point for the development of fatigue fractures in plastics can be internal discontinuities (voids or inclusions) or [[Crack|microcracks]], as well as other [[Surface|surface]] defects caused by the manufacture or processing of the components. On a microscopic scale, no surface is perfectly smooth and flat, but rather exhibits minimal roughness and fine cracks, which cause localised three-dimensional stress concentrations due to the [[Notch Sensitivity|notch effect]].

As a result, the [[Yield Stress|yield strength]] is exceeded in the local area and microplastic deformations occur, which in turn can lead to strengthening effects. The sum of these local [[Deformation|deformation]] processes then forms an initial crack, which spreads deeper into the interior of the material with each load cycle due to energy input and crack propagation. This [[Crack Propagation|crack propagation]] characterises the onset of fatigue fracture. Depending on the test temperature, media exposure, mean stress ''σ''m and stress amplitude ''σ''a, this crack propagation will take a different amount of time until final total fracture.

As a result of the change in load and the cyclic propagation of the crack, typical vibration or oscillation stripes form in the material during the crack propagation phase, but these are only visible with high-resolution microscopic testing methods ([[Scanning Electron Microscopy|scanning electron microscopy (SEM)]] or scanning tunnelling microscopes).

If there are arrest or recovery phases or periods of greatly increased stress during loading, local stress relaxation (see: [[Relaxation Plastics|Relaxation plastics]]) or increased crack propagation occurs, and the fatigue stripes can be seen as arrest lines (see: [[Fracture Types|fracture types]], [[Fractography|fractography]] and [[Waves and Arrest Lines|waves and arrest lines]]) using a loupe or light microscopy.

The arrest lines also become visible because the change in multi-stage stress is always associated with a variation in the crack propagation speed. Since the arrest lines always run perpendicular to the direction of crack propagation, the point of crack initiation can be determined relatively easily based on their arrangement and course. If the time intervals between the stress changes or the arrest lines are known, the number of arrest lines can be used to determine the time at which crack propagation began [3].

==Fatigue fractures in brittle plastics==

In the case of [[Plastics|plastics]] with very low deformability, such as polystyrene ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: PS) or polymethyl methacrylate ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: PMMA), and the presence of micro-notches on the surface or inside the material, a crack tip can form under dynamic stress, which, after initial blunting, exhibits stable crack propagation behaviour (see also: [[Fracture Mechanics|fracture mechanics]] and [[Crack Resistance (R) Curve|crack resistance curve]]). The opening and closing of the crack flanks provides the energy necessary for stable crack propagation under cyclic stress ('''Fig. 2a'''). The structural explanation for this behaviour is the low extensibility of the molecular chains, which are oriented in the stress field in front of the crack tip ([[Crazing|fibrillation]]) and then separated by the advancing crack front ('''Fig. 2b'''), causing the structural integrity of the [[Plastic Component|component]] or test [[Specimen|specimen]] (compliance) to continuously decrease.

[[File:Schwingungsbruch-2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Fracture propagation in brittle plastics with vibration stripes according to [4]
|}

As the crack progresses, parallel vibration stripes form in the material; the characteristics thereof depend on the type of plastic and the load parameters (frequency, mean stress and stress amplitude). Brittle plastics exhibit vibration stripes with very flat profiles and sharp-edged steps between the fracture paths, with inclusions acting as obstacles and only partially visible on the [[Fracture Surface|fracture surface]] surface ('''Fig. 3a'''). The vibration stripes without secondary cracks shown schematically in '''Fig. 3a''' are clearly visible in polyamide 12 in '''Fig. 3b'''. Hard inclusions in the base material are usually bypassed by the crack front, causing them to be covered by the fracture ('''Fig. 4a''') or to lie exposed and separated from the matrix on it ('''Fig. 4b'''). Very soft particles are usually separated from the crack front and are then invisible [4].

[[File:Vibration Fructure Fig-3.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px"|Brittle vibration fractures (a) Schematic diagram and (b) [[Scanning Electron Microscopy|scanning electron microscope]] image of a vibration fracture with arrest lines in spray-dried polyamide 12 ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: PA12)
|}

[[File:Schwingungsbruch-4.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 4''':
|width="600px"|Brittle vibration fractures of (a) compressed styrene-acrylonitrile (abbreviation: SAN) and (b) a polystyrene-rubber compound with embedded polystyrene particles (0.1 to 0.5 µm) ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: PS) according to [4]
|}
|}

As the crack propagates, the remaining load-bearing cross-section decreases, causing the stress to be distributed over an increasingly smaller area. If the [[Tensile Strength|tensile strength]] is exceeded, violent or brittle fracture occurs (see: [[Fracture Types|types of fracture]]). No vibration striations or notch lines are visible in the area of unstable brittle fracture.

==Fatigue fractures in tough plastics==

In [[Toughness|tough]] plastics, the vibration stripes are usually not as clearly defined due to high [[Deformation#Plastic deformation|plastic deformation]], but instead have a wrinkled or rounded appearance. In terms of volume ('''Fig. 5a'''), the vibration fracture paths can also spread out in parallel from different crack initiation positions. The open fracture surface (see also: [[Fractography|fractography]] and [[Component Failure|component failure]]) shows the typical vibration strips ('''Fig. 5b''') with the fracture steps and exposed inclusions on the surface.

[[File:Vibration Fructure Fig-5.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 5''':
|width="600px"|Schematic diagram of ductile vibration fractures (a) in volume and (b) typical habitus of the brittle fracture surface according to [4]
|}

A characteristic vibration fracture surface for a standard-moisture polyamide 66 ([[Plastics – Symbols and Abbreviated Terms|abbreviation: PA 66]]) is shown in '''Fig. 6''' with clearly visible vibration stripes and a wave-like structure.

[[File:Schwingungsbruch-6.jpg|350px]]
{|
|- valign="top"
|width="50px"|'''Fig. 6''':
|width="600px"|Ductile fracture of a polyamide 66 test specimen after [4]
|}

As can be seen, fatigue fracture can be identified in two typical fracture areas: the area of the arrest lines or vibration stripes and the residual fracture surface. This vibration fracture surface is usually relatively smooth, while the brittle fracture surface is generally heavily fractured.

==See also==

* [[Fatigue]]
* [[Fatigue Strength|Fatigue strength]]
* [[Fracture Types|Fracture types]]
* [[Vibration-induced Creep Fracture|Vibration-induced creep fracture]]
* [[Fractography]]

==References==

{|
|-valign="top"
|[1]
|Höninger, H.: Fatigue Behaviour. In: [[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 156–166 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-807-5; see [[AMK-Library]] under A 22)
|-valign="top"
|[2]
|[[Bierögel, Christian|Bierögel, C.]], [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.]: Fatigue Loading. In: [https://de.wikipedia.org/wiki/Wolfgang_Grellmann Grellmann, W.], Seidler, S. (Eds.): Mechanical and Thermomechanical Properties of Polymers. Landolt-Börnstein. Volume VIII/6A3, Springer, Berlin (2014) pp. 241–285, (ISBN 978-3-642-55165-9; see [[AMK-Library]] under A 16)
|-valign="top"
|[3]
|[[Ehrenstein, Gottfried W.|Ehrenstein, G. W.]], Engel, K., Klingele, H., Schaper, H.: Scanning Electron Microscopy of Plastics Failure. Carl Hanser, Munich (2011), (ISBN 978-3-446-42242-1; see [[AMK-Library]] under D 5)
|-valign="top"
|[4]
|Ehrenstein, G. W.: Schadensanalyse an Kunststoff-Formteilen. VDI Publishing Düsseldorf (1981), (ISBN 3-18-404068-2; see [[AMK-Library]] under D 3)
|}

[[Category:Fatigue]]

Velocity

2026-09-07T12:14:13Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Geschwindigkeit}}
{{PSM_Infobox}}
Velocity
__FORCETOC__

==General information==

The term velocity (or synonym also speed) is one of the most frequently used terms in scientific and technical literature. In materials testing and plastics testing and the related literature on testing technology, there is an inconsistent and sometimes not clearly defined variety of terms used to describe the velocity of experimental tests. The terms are often used without further definition and sometimes with contradictory units of measurement for different test methods.

==Mechanical polymer testing==

The following terms are explained in more detail in the [http://192.168.81.5/wiki/index.php/file:Deckblatt_Kunststoffpruefung.jpg WIKI-Lexicon of Polymer Testing and Diagnostics] for the field of mechanical polymer testing:

# Deformation rate
# Deformation speed
# [[Test Speed | Test speed]]
# Strain speed or strain rate
#* Basic principles
#* Applications
# [[Crosshead Speed | Crosshead speed]]

In addition, the terms not explained separately
* Pendulum hammer velocity
* Impact velocity

are frequently used.

Terms related to manufacturing technology are also not explained separately, such as

* the twisting speed
or
* the take-off speed (pull-off speed),

which are used in the plastics industry and textile technology in the production of fibres, threads, films and sheets and have a significant influence on the mechanical properties. The term pull-off speed is also used synonymously in the literature for [[Crosshead Speed | crosshead speed]].

==Fracture mechanical testing==

In the [[Fracture Mechanical Testing | fracture mechanics testing]] of [[Plastics | plastics]] and in the testing of composite materials, the following terms are also used
* [[Crack Tip Opening Displacement Concept (CTOD) | Crack opening displacement velocity]]
* Crack velocity (see crack propagation) and
* Crack propagation velocity (see, among other things, [[Fracture Mechanical Testing | fracture mechanical testing]], fracture types, fatigue crack propagation elastomers and crack propagation stress corrosion cracking).

==Non-destructive polymer testing==

In non-destructive polymer testing, the speed of propagation of different types of waves is used to interpret acoustic phenomena, see e.g. refraction of sound waves or ultrasonic birefringence.

The term ultrasound velocity is also used relatively frequently in the literature, e.g. when explaining the terms acoustic properties, modulus of elasticity ultrasonic measurements, air ultrasound, [[Crack Propagation | crack propagation]], ultrasonic birefringence, transmission of sound waves or [[Ultrasonic Weld Inspection | ultrasonic weld inspection]].

The [[Ultrasonic Runtime Measurement | ultrasound velocity]] is usually specified as the phase velocity. If wave packets with different frequencies occur due to the generation of sound, the wave packets contain waves with different wavelengths. The so-called group velocity is then specified as the average propagation speed of the ultrasound.

==See also==

* [[Test Speed | Test speed]]
* [[Crosshead Speed | Crosshead speed]]
* [[Fracture Mechanical Testing | Fracture mechanical testing]]

==References==

* [[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Polymer Testing Carl Hanser Munich (2022) 3rd. Edition, (ISBN 978-1-56990-806-8; E-Book ISBN 978-156990-807-5; see AMK-Library under A 22)

[[Category:Velocity]]

File:Einachsiger Spannungszustand 4.jpg

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Oluschinski:

File:Einachsiger Spannungszustand 3.jpg

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File:Einachsiger Spannungszustand 2.jpg

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Oluschinski:

File:Uniaxial Stress State-Fig1.jpg

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Oluschinski:

Uniaxial Stress State

2026-09-07T10:44:09Z

Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Einachsiger Spannungszustand}} {{PSM_Infobox}} Uniaxial stress state __FORCETOC__ ==Stress state in tensile and compression test== If a test specimen, which is supposed to be in a plane stress state, is loaded by a tensile or compressive force ('''Fig. 1'''), then, according to the cut reactions with the cut angle ''α'' = 0, a normal..."

{{Language_sel|LANG=ger|ARTIKEL=Einachsiger Spannungszustand}}
{{PSM_Infobox}}
Uniaxial stress state 
__FORCETOC__

==Stress state in tensile and compression test==

If a [[Specimen|test specimen]], which is supposed to be in a [[Plane Stress and Strain State|plane stress state]], is loaded by a tensile or compressive force ('''Fig. 1'''), then, according to the cut reactions with the cut angle ''α'' = 0, a normal force ''F''N corresponding to the external load ''F'' is generated in the test specimen. If there are no internal or external inhomogeneities such as cavities, inclusions or [[Notch|notches]], and if there is no tendency to demould, the applied load is distributed as a surface load over the test specimen cross-section ''A''0 and is specified as a normalised force or normal stress in accordance with '''Eq. (1)'''. This normal stress ''σ''x or ''σ''N has a positive sign in the case of [[Tensile Test|tensile stress]] and a negative sign in the case of compressive stress, and is constant across the test specimen cross-section under the conditions specified [1, 2].

[[File:Uniaxial_Stress_State-Fig1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Uniaxial stress state in the [[Tensile Test|tensile test]] (a) and in the [[Compression Test|compression test]] (b)
|}

{|
|-
|width="20px"|
|width="500px"|<math>\sigma _{x}=\sigma _{N}=\frac{F_{N}}{A_{0}}</math>
|(1)
|}

==MOHR's stress circle==

If the cut reactions are determined at an angle ''α'' > 0, a parallelogram of reaction forces is obtained ('''Fig. 2a''') and, according to '''Eqs. (2)''' and '''(3)''', the normal stress ''σ''N and the [[Bend Test – Shear Stress|shear stress]] ''τ'' acting in the test specimen cross-section are derived from the equilibrium conditions [3].

{|
|-
|width="20px"|
|width="500px"|<math>\sigma _{x}=\frac{1}{2}\sigma _{\alpha} \cdot (1+\cos 2\alpha )</math>
|(2)
|-
|width="20px"|
|width="500px"|<math>r=\frac{1}{2}\sigma _{\alpha}\cdot \sin 2\alpha</math>
|(3)
|}

[[File:Einachsiger_Spannungszustand_2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Cutting reactions at angle ''α'' (a) and MOHR's stress circle (b)
|}

'''Equations (2)''' and '''(3)''' yield '''Eq. (4)''' of MOHR's stress circle (named after Christian Otto Mohr), in which the normal and shear stresses associated with the angle of cut are represented [3].

{|
|-
|width="20px"|
|width="500px"|<math>\left ( \sigma _{N}-\frac{1}{2}\sigma _{\alpha } \right )^{2}+\tau^{2}=\left ( \frac{1}{2}\sigma _{\alpha } \right )^{2}</math>
|(4)
|}

The illustration in '''Fig. 2b''' shows that the maximum shear stress occurs at an angle of 45°, and is therefore ''τ''max = ''σ''α/2. Macroscopically, the shear stress component manifests itself in [[Tensile Test|tensile]] or [[Compression Test|compression tests]], for example, through slip or shear fracture and deformation cones in ductile metals, as well as through flow lines visible on the [[Surface|surface]], also known as Lüders lines. In [[Plastics|plastics]], so-called [[Shear Band Formation|shear bands]] can be observed on the surface of the test specimen in tensile tests under certain test conditions, which represent one of the dominant deformation processes ('''Fig. 3'''). In [[Ductility Plastics|ductile plastics]] that constrict, the flanks of the constriction fronts often have an angle of approximately less than 45°.

[[File:Einachsiger_Spannungszustand_3.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px"|Shear bands in acrylonitrile butadiene styrene ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: ABS) in tensile testing
|}

==Stress distribution in three-point bending==

A special case of uniaxial stress occurs in the case of pure [[Bend Test|bending]] about one axis, whereby, however, an inhomogeneous stress state occurs here due to the simultaneous occurrence of tensile, compressive and shear stresses [2, 4]. In the case of identical tensile and compressive properties of the material under investigation, the maximum stress ''σ''f in the peripheral fibre ( see: [[Peripheral Fibre Strain|peripheral fibre strain]]) of the test specimen is calculated according to '''Eq. (5)''' for [[Bend Test#The three-point bending test method|three-point bending]], and the stress distribution in the cross-section is symmetrical with the neutral or stress- and strain-free axis ('''Fig. 4a''').

{|
|-
|width="20px"|
|width="500px"|<math>\sigma _{f}=\frac{3\cdot F\cdot L}{2\cdot b\cdot h^{2}}</math>
|(5)
|}

Due to the shear force bending, additional shear stresses occur in the cross-section, which are distributed parabolically and reach their maximum in the neutral fibre or axis ('''Fig. 4b'''). These shear stresses are negligible in the [[Bend Test|bending test]] on plastics if the condition [[Support Distance|span]] ''L''/specimen thickness ''h'' ≥ 16 is fulfilled.

In simplified terms, the maximum shear stress can be calculated for a rectangular cross-section according to '''Eq. (6)''' [3]:

{|
|-
|width="20px"|
|width="500px"|<math>\tau_{max}=\frac{3\cdot F}{4\cdot b\cdot h}</math>
|(6)
|}

[[File:Einachsiger_Spannungszustand_4.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 4''':
|width="600px"|Normal stress distribution (a) and shear stress distribution (b) in the cross-section of a test specimen under three-point bending
|}

Due to the shear sensitivity of laminates or layered [[Composite Materials Testing|composite materials]] and the potential risk of delamination, these [[Material & Werkstoff|materials]] must satisfy the condition ''L''/''h'' ≥ (20−25) in bending tests. If the material exhibits different tensile and compressive behaviour, a displacement of the neutral fibre occurs, resulting in a non-linear and asymmetrical stress distribution in the cross-section.

==See also==

* [[Compression Test|Compression test]]
* [[Tensile Test|Tensile test]]
* [[Bend Test|Bend test]]
* [[Plane Stress and Strain State|Plane stress and strain state]]
* [[Multiaxial Stress State|Multiaxial stress state]]

==References==

{|
|-valign="top"
|[1]
|Lüpke, T.: Fundamental Principles of Mechanical Behavior. In: [[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022), 3rd Edition pp. 71–86 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-807-5; see [[AMK-Library]] under A 22)
|-valign="top"
|[2]
|[[Bierögel,_Christian|Bierögel, C.]]: Quasi-static Test Methods. In: [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.], Seidler, S. (Eds.): Polymer Testing. Carl Hanser, Munich (2022), 3rd Edition pp. 101–143 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-807-5; see AMK-Library under A 22)
|-valign="top"
|[3]
|Szabo, I.: Einführung in die Technische Mechanik. Springer, Berlin Heidelberg (1984) 8th Edition (ISBN 3-540-13293-7)
|-valign="top"
|[4]
|Erhard, G.: Konstruieren mit Kunststoffen. Carl Hanser, Munich (2008) 7th Edition, pp. 189–198 (ISBN 978-3-446-41646-8)
|}

[[Category:Deformation]]
[[Category:Compression Test]]
[[Category:Tensile Test]]

Ultrasound Testing

2026-09-07T10:43:46Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Ultraschallprüfung}}
{{PSM_Infobox}}
Ultrasound testing
__FORCETOC__

==History of ultrasound==

Flaw detection based on ultrasound is one of the oldest [[Non-destructive Testing (NDT) | non-destructive testing methods]] alongside X-ray gross structure analysis. Following the discovery of the [[Piezoelectric Force Transducer|piezoelectric effect]] (1880–1881) by the Curie brothers for measuring and generating non-stationary pressures and vibrations, the beginnings of the technical utilisation of ultrasound can be dated to around 1940. It was recognised that ultrasound interacts with the workpiece to be tested and reacts with a change in intensity and transit time. In 1942, the technical foundations were laid for time-of-flight measurement with separate transmitter and receiver sensors in through-transmission mode (Trostzange) and later for pulse-echo technology. In the years 1949–1950, Krautkrämer, Hürth, developed the first analogue ultrasonic testing device for non-destructive fault detection using [[Pulse-Echo Ultrasonic Technique | pulse-echo ultrasonic technique]]. In 1973, Karl Deutsch released the first device with a digital display and in 1982 the Echograph with an integrated microprocessor.

Following the development of angle beam sensors (approx. 1952) and [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|transmitter-receiver sensors]] (approx. 1957), welded joints and thin components could be analysed for specific manufacturing or processing-related defects. The development of [[Ultrasonic Immersion Bath Technique | ultrasonic immersion bath technology]] using imaging ultrasound can be dated to around 1970 and squirter technology and [[Air-Ultrasound | air-ultrasound]] to around 1980 [1, 2]. More recent developments in digital testing technology, phased array technology, the TOFD testing and evaluation method (Time of Flight Diffraction Technique) or guided waves prove that the physical limits of ultrasonic testing technology are far from exhausted.

==Ultrasonic testing technology==

Ultrasonic testing is an active acoustic testing method in which ultrasonic waves (longitudinal or transverse waves) are transmitted into a test piece using one or more sensors (sensor field) to detect internal defects (imperfections) or determine geometric dimensions (wall thickness). Using a second sensor (receiver in through-transmission technology) or after switching the transmitter to receive ([[Pulse-Echo Ultrasonic Technique|pulse-echo technology]]), the sound waves, which have changed in transit time, frequency and intensity, are received and further processed for display purposes, utilising the inverse piezoelectric effect.

Ultrasonic testing, known in medicine as sonography, is based on the use of ultrasonic waves with a frequency > 20 kHz, whereby technical applications use the frequency range from approx. 100 kHz to 100 MHz. As the sound waves propagate in different media at different ultrasound velocities (see: [[Ultrasonic Runtime Measurement | ultrasonic runtime measurement]]) and are reflected, shadowed, refracted or scattered and weakened at media interfaces with different sound impedance (air, water, metal), these physical effects can be used to detect defects or imperfections (blowholes, inclusions), whereby generally only defects that are greater than half the wavelength (''λ''/2) are recognisable. These methods can be used to determine the type and size of defects based on known target values and the depth of the discontinuity in the test piece can be determined using time-of-flight measurement. However, due to different acoustic impedances at external interfaces, coupling agents (oil, water) are usually required to introduce the ultrasound into the test piece, which minimise the [[Ultrasonic Waves Reflection | reflection]] of the ultrasound at the [[Surface|surface]] [3−6] or improve the [[Transmission Sound Waves|transmission]] of sound waves into the solid.

==Ultrasonic sensors==

Depending on the application and type of wave, different [[Ultrasonic Sensors|ultrasonic sensors]] are used in practice:

* [[Ultrasonic Standard Sensors|Standard sensors]]
* [[Ultrasonic Angle Beam Sensors|Angle sensors]]
* [[Ultrasonic Transmitter(S)-Receiver(E) Sensor | Transmitter (S)-receiver (E) sensors]]
* [[Ultrasonic Composite Sensors|Composite sensors]]
* [[Ultrasonic Shock Wave Sensors|Shock wave sensors]]
* [[Ultrasonic Immersion Bath Sensors|Immersion bath sensors]]
* [[Ultrasonic Phased Array Sensors|Phased array sensors]]

==Imaging visualisation==

The simplest display method in ultrasonic testing is the [[A-Scan Technique|A-scan]], which represents the square of the [[HF-Scan|HF-scan]]. Scanning imaging test methods ([[Ultrasonic Immersion Bath Technique | immersion bath]], phased array technology or air ultrasound) can be used to generate the [[B-Scan Technique|B-]], [[C-Scan Technique|C-]] and [[D-Scan Technique|D-scan]] or the [[F-Scan Technique|F-scan]] with significantly improved informative value through frequency-related evaluation. Special inspection and evaluation techniques such as [[Ultrasonic Time-of-Flight Diffraction (TOFD) Technique|TOFD]] (time-of-flight diffraction technique) or SAFT (Synthetic Aperture Focusing Technique) are also available.

In principle, ultrasonic testing is standardised in ISO 16810 and the terminology used is standardised in DIN EN 1330-4, whereby special standards apply for the various applications on [[Ultrasonic Weld Inspection|welded joints]], forgings or [[Ultrasonic Wall Thickness Measurement | wall thickness measurement]], although mostly only for metallic materials [7, 8]. There are currently no binding standards for ultrasonic testing of [[Plastics | plastics]].

==Qualification of ultrasonic inspectors==

A personnel certification (DPZ certificate), usually from the [https://en.wikipedia.org/wiki/German_Research_Foundation German Society for Non-Destructive Testing – DGZfP], is required to carry out ultrasonic testing and is valid for 5 years for a specific testing method [9]. There are 3 qualification levels 1 to 3 (Level) for ultrasonic testing UT, which are also adapted to the various areas of application (e.g. aerospace industry, welding technology or cast part and pipe production).

==See also==

* [[Non-destructive Polymer Testing | Non-destructive polymer testing]]
* [[Acoustic Properties | Acoustic properties]]
* [[Ultrasound – Elastic Parameters | Ultrasound – Elastic parameters]]
* [[Air-Ultrasound | Air-ultrasound]]
* [[Ultrasonic Runtime Measurement | Ultrasound runtime measurement]]

==References==

{|
|-valign="top"
|[1]
|Husarek, V., Castel, J. G.: [https://www.ndt.net/article/dgzfp01/papers/v03/v03.htm Beitrag zur Geschichte der Ultraschallprüfung in Deutschland und Frankreich]. DGZfP-Jahrestagung „Zerstörungsfreie Werkstoffprüfung“ 2001, Sofranell, Frankreich, Proceedings 75-CD
|-valign="top"
|[2]
|Guicking, D.: Erwin Meyer – Ein bedeutender deutscher Akustiker – Biographische Notizen. Universitätsdrucke, Universitätsverlag, Göttingen (2012), ([http://www.guicking.de/dieter/Erwin-Meyer.pdf http://www.guicking.de/dieter/Erwin-Meyer.pdf]) (accessed on 26/05/2025)
|-valign="top"
|[3]
|Krautkrämer, J., Krautkrämer H.: Werkstoffprüfung mit Ultraschall. Springer, Berlin (1986), (ISBN 978-3-662-10909-0)
|-valign="top"
|[4]
|Deutsch, V., Platte, M., Vogt, M.: Ultraschallprüfung – Grundlagen und industrielle Anwendungen. Springer, Berlin (1997), (ISBN 3-540-62072-9; see [[AMK-Library]] under M 45)
|-valign="top"
|[5]
|Matthies, K. u. a.: Dickenmessung mit Ultraschall. DVS-Verlag GmbH, 2nd Edition, Berlin (1998), (ISBN 3-87155-940-7; see [[AMK-Library]] under M 44)
|-valign="top"
|[6]
|Schiebold, K.: Zerstörungsfreie Werkstoffprüfung – Ultraschallprüfung. Springer, Berlin (2014), (ISBN 978-3-662-44699-7)
|-valign="top"
|[7]
|ISO 16810 (2024-10): Non-destructive Testing – Ultrasonic Testing – General Principles
|-valign="top"
|[8]
|DIN EN 1330-4 (2010-05): Non-destructive Testing – Terminology – Part 4: Terms Used in Ultrasonic Testing (withdrawn; replaced by ISO 5577 (2025-09))
|-valign="top"
|[9]
|ISO 9712 (2021-12): Non-destructive Testing – Qualification and Certification of NDT Personnel
|-valign="top"
|}

[[Category:Acoustic Test Methods_Ultrasonics]]
[[Category:Velocity]]

File:US gefuehrte Wellen-2.jpg

2026-09-07T10:43:20Z

Oluschinski:

File:US gefuehrte Wellen-1.jpg

2026-09-07T10:43:11Z

Oluschinski:

Ultrasound-guided Waves

2026-09-07T10:42:42Z

Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Geführte-Wellen}} {{PSM_Infobox}} Ultrasound guided waves __FORCETOC__ ==Definition of guided waves== By definition, ‘guided waves’ are types of waves that propagate in the main axis direction of a comparatively thin medium, i.e. they are conducted or guided through the medium. The distance or thickness ''d'' of the confining surface layers in the normal direction is..."

{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Geführte-Wellen}}
{{PSM_Infobox}}
Ultrasound guided waves
__FORCETOC__

==Definition of guided waves==

By definition, ‘guided waves’ are types of waves that propagate in the main axis direction of a comparatively thin medium, i.e. they are conducted or guided through the medium. The distance or thickness ''d'' of the confining surface layers in the normal direction is approximately in the order of magnitude of the wavelength ''λ'', i.e. ''d'' ≈ ''λ''. The term ‘guided waves’ is therefore justified by the ‘guidance’ of the waves through the geometry of the tested [[Plastic Component|component]], although [https://en.wikipedia.org/wiki/Lamb_waves Lamb] or plate waves are generally a vibration-related property of thin plates or membranes, as is the hat wave.

==Types of waves and their propagation==

The plate waves or guided waves, which propagate differently from Rayleigh waves (surface waves, see '''Fig. 1a'''), Stoneley waves and Love waves ('''Fig. 1b''') in the presence of [[Phase Boundary Surface|interface surfaces]], are divided into symmetric and asymmetric plate or Lamb waves ('''Fig. 2''') and represent their vibration modes. Stoneley and Love waves, which are also known from seismology [1], have so far been of little significance in [[Non-destructive Testing (NDT)|non-destructive testing (NDT)]], but are already being used for special applications in [[Ultrasound Testing|ultrasound testing]] [2−4]. Surface waves (Fig. 1a) are very important for [[Sound Emission Testing|sound emission testing]] (SEP) and acousto-ultrasonics testing, as these waves are only slightly attenuated in their direction of propagation and can therefore be received over long distances, whereby special AE probes are used [5, 6]. The symmetric plate wave ('''Fig. 2a''') is also referred to as the S-type and the asymmetric wave as the A-type ('''Fig. 2b''') with different vibration modes (index 1, 2, 3) if the wavelength becomes very small. With such geometric wave types, the propagation velocity generally depends on the wavelength and leads to [[Dispersion|dispersion]] phenomena in the [[Material & Werkstoff|material]].

[[File:US_gefuehrte_Wellen-1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Direction of propagation (AR) and direction of vibration (SR) of (a) Rayleigh waves and (b) Love waves
|}

[[File:US_gefuehrte_Wellen-2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Examples of guided waves: (a) symmetric plate wave, (b) asymmetric plate wave (Lamb waves) with the direction of propagation (AR) and direction of vibration (SR)
|}

Plate waves with limited geometries, as shown in '''Figure 2a''', are also referred to as expansion or compression waves, whereby it can be seen that the neutral fibre of the plate does not change its geometric position (pure longitudinal vibration), in contrast to the asymmetrical wave in '''Figure 2b''', where the neutral fibre performs a transverse vibration. It is typical for Lamb waves that also harmonics can occur, although their amplitude decreases significantly with increasing order.

==Requirements for component testing==

The guided surface waves do not emerge from the [[Material & Werkstoff|material]] but remain ‘attached’ to the geometry, similar to light waves in glass fibres. This means that possible geometric changes, such as component curvatures or edges, do not pose an obstacle for these waves and (due to ''d'' ≈ ''λ'') no [[Ultrasonic Waves Reflection|reflection]] of sound waves occurs at them. As a result, the loss of sound energy into the adjacent media is considerably lower than with established methods of [[Ultrasound Testing|ultrasound testing]], such as the [[Pulse-Echo Ultrasonic Technique|pulse-echo method]]. The guided waves therefore propagate almost undamped in the tested medium and can therefore be transmitted over relatively long distances to perform tests on [[Plastic Component|components]] that are inaccessible in places, such as pipe penetrations under roads or buildings [7]. Guided waves are actively excited in the component to be tested by means of a suitable transmitter and received by the identical receiver (echo mode) or an additional ultrasonic probe ([[Ultrasonic Transmission Technique|transmission mode]]).

When propagating guided waves, however, it should be noted that different wave modes can be excited depending on the excitation frequency and the component thickness, and [[Dispersion|dispersions]] can occur [8], which can sometimes make it considerably more difficult to interpret structural damage that has occurred.

==Application examples for guided waves==

However, guided waves have a wide range of applications and are particularly useful when sections of large [[Component Testing|components]], such as pipes or tanks, are difficult to access. Current technical literature cites the following areas of application [9−13]:

* Inspection of plates,
* Pipe inspection,
* Inspection of [[Adhesive Joints – Determination of Characteristic Values|adhesive joints]],
* Airfoil inspection,
* Structural monitoring for early damage detection (permanent),
* Inspection of wind turbines (rotor blades),
* Container and tank inspection.

==See also==

* [[Ultrasonic Direct Coupling|Ultrasonic direct coupling]]
* [[Ultrasound – Elastic Parameters|Ultrasound – Elastic parameters]]
* [[Ultrasonic Modulation|Ultrasonic modulation]]
* [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|Ultrasonic transmitter(S)-receiver(E) sensors]]
* [[Ultrasonic Wall Thickness Measurement|Ultrasonic wall thickness measurement]]

==References==

{|
|-valign="top"
|[1]
|Clauser, C.: Einführung in die Geophysik. Springer, Berlin Heidelberg, 2nd Edition (2016), (ISBN 978-3-662-46883-8)
|-valign="top"
|[2]
|Malischewsky, P. G., Schnapp, J.-D.: Oberflächenwellen und Materialprüfung aus seismologischer Sicht. DGZfP-Dach Jahrestagung, Salzburg (2004)
|-valign="top"
|[3]
|Wendrich, A.: Zerstörungsfreie Ortung von Anomalien in historischem Mauerwerk mit Radar und Ultraschall – Möglichkeiten und Grenzen. ([https://e-pub.uni-weimar.de/opus4/frontdoor/index/index/start/0/rows/10/sortfield/score/sortorder/desc/searchtype/simple/query/Zerst%C3%B6rungsfreie+Ortung+von+Anomalien+in+historischem+Mauerwerk+mit+Radar+und+Ultraschall+%E2%80%93+M%C3%B6glichkeiten+und+Grenzen/docId/1397 Dissertation]), Bauhaus-Universität Weimar (2008)
|-valign="top"
|[4]
|Jüngert, A.: Untersuchung von GFK-Bauteilen mit akustischen Verfahren am Beispiel der Rotorblätter von Windenergieanlagen. ([https://www.deutsche-digitale-bibliothek.de/item/OP6NMQB4ID6D36DV2L6L32K4JFFSD7IE?isThumbnailFiltered=true&query=Untersuchung+von+GFK-Bauteilen+mit+akustischen+Verfahren+am+Beispiel+der+Rotorbl%C3%A4tter+von+Windenergieanlagen&rows=20&offset=0&viewType=list&firstHit=OP6NMQB4ID6D36DV2L6L32K4JFFSD7IE&lastHit=lasthit&hitNumber=1 Dissertation]), Universität Stuttgart (2010) (access on November 30, 2025)
|-valign="top"
|[5]
|Meyer, E., Neumann, E.-G.: Physikalische und technische Akustik. Springer Verlag, Berlin, 2nd Edition, (2013), (ISBN 978-3-322-91086-8)
|-valign="top"
|[6]
|Grosse, C. U., Ohtsu, M. (Eds.): Acoustic Emission Testing. Springer Verlag, Berlin (2008), (ISBN 978-3-540-69895-1)
|-valign="top"
|[7]
|Prager, J., Gravenkamp, H., Rahman, M.-U., Köppe, E.: Einsatz geführter Wellen für die Ultraschallprüfung. tm − Technisches Messen Plattform für Methoden, Systeme und Anwendungen der Messtechnik. 79 (2012) 5, pp. 251–261, DOI: https://www.degruyter.com/document/doi/10.1524/teme.2012.0168/html
|-valign="top"
|[8]
|Schmidt, D.: Modenselektive Übertragung von Lambwellen in Faserverbundstrukturen. [https://www.gbv.de/dms/bs/toc/795057849.pdf Dissertation], Technische Universität Braunschweig (2014) (access on November 30, 2025)
|-valign="top"
|[9]
|Prager, J., Köppe, E. Bartholmai, M.: Früherkennung von Strukturschäden mittels geführter Lamb-Wellen. GMA/ITG-Fachtagung Sensoren und Messsysteme. Proceedings (2012) pp. 531–540
|-valign="top"
|[10]
|Schubert, L., Klesse,T., Weihnacht, B., Schulze, E., Lieske, U., Frankenstein, B.: Aktuelle Entwicklungsarbeiten zu aktiv angeregten geführten Wellen (Acousto-Ultrasonics) für SHM-Anwendungen. 20. Kolloquium Schallemission, DGZfP (2015) https://www.ndt.net/search/docs.php3?id=20941
|-valign="top"
|[11]
|Rau, E., Bamberg, J., Berwig, P.: Ultraschallprüfung an Turbinenschaufeln mittels Oberflächenwellen. DGZfP-Seminar FA Ultraschallprüfung (2015), Lecture No. 8; https://www.ndt.net/article/dgzfp-ut-2015/papers/8.pdf
|-valign="top"
|[12]
|Prager, J., Brackrock, D., Dohse, E., Gaal, M., Homann, T., Grezeszkowski, M.: Anwendung geführter Ultraschallwellen für die Prüfung von Klebeverbindungen. DGZfP-Dach Jahrestagung, Potsdam (2014)
|-valign="top"
|[13]
|Schiebold, K.: Zerstörungsfreie Werkstoffprüfung – Ultraschallprüfung. Springer, Berlin (2014), (ISBN 978-3-662-44699-7)
|}

==Weblink==

* Wikipedia – The free encyclopedia: https://en.wikipedia.org/wiki/Lamb_waves (access on February 25, 2026)

[[Category:Acoustic Test Methods_Ultrasonics]]

Ultrasound – Elastic Parameters

2026-09-07T10:42:24Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Elastische Kennwerte}}
{{PSM_Infobox}}
Ultrasound – Elastic parameters

Determination of the elastic parameters with ultrasound
__FORCETOC__

==General==

The determination of elastic [[Material Value | material values]] by means of ultrasonic measurement technology is a measurement method of non-destructive plastics testing which, under certain conditions, provides more accurate results compared to the tensile test with longitudinal and transverse extensometers than is possible in the material testing machine with mechanical or optical extensometers. In addition, this method is very economical, as it is not only non-destructive, but can also be carried out relatively quickly.

The calculation equations of the modulus of elasticity, the shear modulus, the compression modulus and the [[Poisson's Ratio | Poisson's ratio]] are derived from the theory of elasticity, which contain the mass density and the longitudinal and transverse sound velocities of the tested material [1].

These equations apply exactly to materials with linear-elastic behaviour such as metals and ceramics and can therefore only be used approximately for heterogeneous materials. For plastics, it should be noted that due to their viscoelasticity – and also the heterogeneity of the semi-crystalline polymers – a high sound attenuation is generally to be expected, and stronger scattering occurs in the measurement series [2, 3]. That's why lower measuring frequencies are to be used for these materials, whereby the inhomogeneities should be several times smaller than the wavelength, so that the calculation equations, as listed below, are still valid.

==Specimen==

In order to carry out the measurements, a special geometry of test [[Specimen | specimens]] is necessary, which allows an accurate determination of the longitudinal and transverse ultrasonic velocities. The following figure ('''Fig. 1''') shows a possible geometry.

[[file:US_Elastische_Kennwerte-1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Prismatic test specimen with bevelled edge
|}

The geometry of a cuboid allows the measurement of both sound velocities, with the bevel adapted to the direction of the sound beam incident from the angle probe (the main axis of the sound field forming) (cf. '''Fig. 2b'''). This adjustment is made so that the transverse wave (see also: Refraction of sound waves) hits the bevel perpendicularly.

==Measurement of sound velocities==

For the measurement of the longitudinal sound velocity ''c''L, a normal probe (also called perpendicular transducer) is used according to the [[Pulse-Echo Ultrasonic Technique | pulse-echo method]]. It is coupled to the test specimen (according to '''Fig. 2a''') in such a way that the main axis (= acoustic axis) of the developing sound field meets the two opposite plane-parallel surfaces of the test specimen perpendicularly. This means that the acoustic axes of the sound fields of the incoming sound beam and the sound beam returning from the wall are the same, and the speed of sound can be calculated using the formula

{|
|-
|width="20px"|
|width="500px" | <math> c_{L} = \frac{2 d}{t_{S}}</math>.
|(1)
|}

Within the time ''t''S (sound travel time), the sound wave travels through twice the thickness ''d''.

[[file:US_-_Elastic_Parameters_2.jpg|700px]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Prismatic specimen with bevelled edge and coupling of a normal ('''a''') and an angle probe ('''b''')
|}

To measure the transverse sound velocity ''c''T, the angle probe is aligned so that the sound beam, i.e. the main axis of the sound field, is perpendicular to the bevelled surface ('''Fig. 2b'''). The longitudinal sound velocity is determined completely analogously according to formula (1).

==Determining the elastic material parameters==

The material's moduli ([[Elasticity|elasticity]] (''E''), shear (''G''), compression (''K'') modulus) as well as the [[Poisson's Ratio|Poisson's ratio]] ''μ'' result from the relationships between the linear-elastic material parameters and the density ''ρ'' as well as the speed of sound. They have the following form:

{|
|-
|width="20px"|
|width="500px" | <math>E = \varrho \frac{3 \ c_{L}^{2} c_{T}^{2} - 4 c_{T}^{4}}{\ c_{L}^{2}-\ c_{T}^{2}}</math>
|(2)
|}

{|
|-
|width="20px"|
|width="500px" | <math>G = \varrho\ c_{T}^{2}</math>
|(3)
|}

{|
|-
|width="20px"|
|width="500px" | <math>K = \frac{G\ E}{9G-3E^{'}}</math>
|(4)
|}

{|
|-
|width="20px"|
|width="500px" | <math>\mu = \frac{1}{2} \frac{c_{L}^{2} -2 c_{T}^{2}} {\ c_{L}^{2}-\ c_{T}^{2}}</math>
|(5)
|}

Strictly speaking, these relations apply to isotropic solids. Thus, these equations are exactly valid for homogeneous (non-porous) ceramics [4]. However, they can also be used as a good approximation to determine the elastic properties of heterogeneous materials. This is always the case when the inhomogeneities (see: [[Failure Analysis – Basics|damage analysis]] and [[Component Failure|component failure]]) in the materials are small compared to the wavelength at which ultrasonic waves propagate in the material.

==Comments on the accuracy of the procedure==

The structure of the sound field is different for normal and angle beam probes. The normal probe has an axially symmetrical sound field that tapers off as the nominal frequency of the probe increases. This makes it possible to measure the speed of sound very accurately if both the surface on which the transducer is placed and the sounded boundary surface (see: [[Phase Boundary Surface | phase boundary surface]]) are normal to the axis of the sound field. Here, if the sound attenuation is not too high, the multiple echo method is recommended (see: [[Ultrasonic Wall Thickness Measurement | ultrasonic wall thickness measurement]]).

The inaccuracies are more likely to occur with the angle probe, whose sound field has a larger divergence angle (see: [[Ultrasonic Standard Sensors| ultrasonic standard sensors]]). Thus, according to the distance law <math>I = I_0 \cdot r^{-2}</math>, the reflected amplitude of the wave emitted by the angle probe is significantly lower than that of the normal probe. Here ''I''0 represents the intensity of the wave emitted by the probe, I that of the received wave and r the double distance between probe and reflecting surface. This sound attenuation is therefore greater with the angle probe. In addition, the nominal frequency of angle probes is limited to a maximum of 5 MHz [5], which means that the same accuracy cannot be achieved as with a normal probe (≥ 10 MHz). Therefore, the angle probe should first be calibrated to measure the transverse sound velocity.

==See also==

* [[Ultrasonic Direct Coupling | Ultrasonic direct coupling]]
* [[Pulse-Echo Ultrasonic Technique | Pulse-echo ultrasonic technique]]
* [[Ultrasonic Weld Inspection | Ultrasonic weld inspection]]
* [[Ultrasonic Runtime Measurement | Ultrasonic runtime measurement]]
* [[Ultrasonic Immersion Bath Technique | Ultrasonic immersion bath technique]]

==References==

{|
|-valign="top"
|[1]
|Landau, L. D., Lifschitz, E. M.: Lehrbuch der theoretischen Physik – Elastizitätstheorie Bd. 7, Akademieverlag Berlin (2009)
|-valign="top"
|[2]
|Krautkrämer, J., Krautkrämer, H.: Die Schwächung von Ultraschallwellen in festen Stoffen. In: Krautkrämer, J., Krautkrämer, H. (Hrsg.): Werkstoffprüfung mit Ultraschall. Springer Verlag Berlin, Heidelberg (1990) (ISBN 978-3-662-1082-2)
|-valign="top"
|[3]
|[[Grellmann, Wolfgang|Grellmann, W.]], [[Bierögel, Christian|Bierögel, C.]], [[Reincke, Katrin|Reincke, K.]] (Eds.): Wiki „Lexikon Kunststoffprüfung und Diagnostik“ 2025, Version 15, https://wiki.polymerservice-merseburg.de/index.php/Absorption_Schallwellen
|-valign="top"
|[4]
|DIN EN 843-2 (2007): Hochleistungskeramik – Mechanische Eigenschaften monolithischer Keramik bei Raumtemperatur – Teil 2: Bestimmung des Elastizitätsmoduls, Schubmoduls und der Poissonzahl
|-valign="top"
|[5]
|Waygate Technologies – Baker Hughes Company.: Ultraschallprüfköpfe für Fehlernachweise und Größenbestimmungen. Baker Hughes Company (2020) https://www.bakerhughesds.com/sites/g/files/cozyhq596/files/2020-07/bhcs34592-de_ultrasonic_transducers_catalog_r9.pdf (Zugriff am 06.02.2023)
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

Ultrasonic Weld Inspection

2026-09-07T10:42:01Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Schweißnahtprüfung}}
{{PSM_Infobox}}
Ultrasonic weld inspection
__FORCETOC__

==Weld inspection with ultrasound==

In the weld inspection with ultrasound on metals, especially on steels, testing methods are successful and established for decades in practical use. Weld inspection with polymers have diverse problems, which results of its visco-elasticity, the high damping and scattering inside the materials.

Thereby, the ultrasound experiences a high absorption (sound damping) during transmission through the polymer and comparatively low refraction of sound waves at the transition from the ultrasonic transducer over the coupling medium in the polymer.

==Principle of the angular beam==

A favoured method for the weld inspection is the angular radiation by angle-beam probes. Though the angles are mostly fixed depending on the material, which is to be tested. At the interface of transducer/material, a transformation of wave modes happens. According to the law of refraction by Snellius at the interface of two media the longitudinal wave is refracted (and reflected) as well as is also converted in a transversal wave.

[[file:Ultrasonic Weld Inspection 1.jpg|600px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Schematic drawing of (a) an angular radiation by means of an angle-beam probe and (b) the transformation of wave modes at the interface between probe (transducer) and the test object
|}

Therefore, in a solid specimen, two types of wave propagating: 1. the longitudinal wave (compression wave) and 2. the transversal wave (shear wave). The longitudinal wave propagates lengthwise and the transversal wave crosswise to the direction of propagation.

This process for the critical angle of the total reflectance is shown in '''Fig. 1a'''. There the refracted longitudinal wave have the critical angle of the total reflectance (red arrow) and only the transversal wave (blue arrow) propagates in the object volume, wherewith only the transversal wave exists in the material, which simplified the interpretation of the received signal. The general case for an incident angle, which deviated from the critical angle, is shown in '''Fig. 1b'''.

==Angular beaming on polymers==

The disadvantage of the angular radiation on polymers over metals is founded in the relative low difference of impedance among the transducer (with matching layer) and the polymer. Therewith, two wave modes exist in the polymeric material, which complicate the interpretation notably. Here, an analysis of the beam path helps. A normal-beam probe is shown in '''Fig. 2''' that simulate an angle-beam probe by intro-mission in a defined angle to the surface of the specimen. By means of the law of refraction by SNELLIUS (Equation (1)) and the geometrical conditions, the sound paths are calculated.

{|
|-
|width="20px"|
|width="500px"|<math>\frac{Sound velocity\; in\; the\; medium}{Angle\; in\; the\; medium}= const.</math>
|(1)
|}

For minimising the sound loss at direct coupling on polymers, between probe and specimen water will be used as coupling medium. The longitudinal wave emitted from the probe or transducer (red beam) is refracted on the sample surface and hive the incident wave in a longitudinal wave (red) and a transversal wave (green). Both sound beams are reflected at the back wall and the weld joint (dark stripe) and get off the specimen reach the ultrasound probe partly. Though, it is to see that the diameter of the probe influences importantly the size of the measurable surface of the weld joint. It is assumed, that flaws in the weld joint trigger a signal off at the ultrasound probe, because these flaws begins to oscillate with the ultrasound and beam in all directions, then more small transducer can be used.

[[file:Ultrasonic Weld Inspection 2.jpg|400px]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Principle of ultrasonic weld inspection; the red beams stand for the incident longitudinal wave, the green ones for the transversal waves and the blue ones the reflected waves back in the coupling medium
|}

==Example for ultrasonic weld inspection on poly(methylmethacrylate) (PMMA)==

Which interpretative difficulties a measurement of weld joints is making, shows the following example. In '''Fig. 3''' the upper surface of a welded polymer sample (of two identical materials) is shown. The welding joint (WJ) is manufactured by hot plate butt welding method.

[[file:Ultrasonic Weld Inspection 3.jpg|450px]]
{|
|- valign="top"
|width="50px"|'''Bild 3''':
|width="600px"|Schema of a specimen on poly(methylmethacrylate) (abbr.: PMMA) with weld joint where copper stripes are embedded as flaws (top view)
|}

In the '''Figure 3''' the welded influence zone (WIZ) is shown (reddening), which makes difficult the evaluation of the measurement's result by changed material properties. Because of the high sound absorption and the inclined incidence of sound, the signal ('''Fig. 4''') is very noisy. By means of a sound beam analysis, the individual echoes can be assigned to the defined incidents.

[[file:Ultrasonic Weld Inspection 4.jpg|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 4''':
|width="600px"|Example of a HF-Scan at angular radiation with [[Ultrasonic Immersion Bath Technique | immersion bath technique]] in a PMMA specimen with weld joint and embedded copper stripes as flaws
|}

According to the measuring set-up, four surface echoes are found in different depths whereby one of that interfere with a (simulated) flaw, which can be confirmed by an analysis of the sound beam.

==See also==

* [[Ultrasonic Direct Coupling | Ultrasonic direct coupling]]
* [[Pulse-Echo Ultrasonic Technique | Pulse-echo ultrasonic technique]]
* [[Ultrasonic Immersion Bath Technique | Ultrasonic immersion bath technique]]
* [[Ultrasonic Runtime Measurement | Ultrasonic runtime measurement]]
* [[Ultrasound – Elastic Parameters | Ultrasound – Elastic parameters]]

==References==

{|
|-valign="top"
|[1]
|Leger, A., Deschamps, M.: Ultrasonic Wave Propagation in Non-Homogeneous Media. Springer Berlin Heidelberg (2009), (ISBN 978-3-540-89104-8)
|-valign="top"
|[2]
|Krautkrämer, J., Krautkrämer, H.: Attenuation of Ultrasonic Waves in Solids. In: Ultrasonic Testing of Materials. Springer Berlin (1990), (ISBN 978-3-662-10682-2)
|-valign="top"
|[3]
|Deutsch, V., Platte, M., Vogt, M.: Ultrasonic Testing. Fundamentals and Industrial Applications. Springer Berlin (1997), (ISBN 978-3-540-62072-9)
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

Ultrasonic Waves Reflection

2026-09-07T10:41:38Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Reflexion Schallwellen}}
{{PSM_Infobox}}
Ultrasonic waves reflection
__FORCETOC__

==Physical fundamentals==

Alongside [[Transmission Sound Waves|transmission]] and [[Absorption Sound Waves|absorption]], the reflection of sound waves is a phenomenon that occurs at the external or internal [[Phase Boundary Surface|boundary surfaces]] of materials or test pieces.

The law of reflection ('''Eq. 1''') means that the angle of reflection ''β'' is identical to the angle of incidence ''α'', and both lie with the normal (plumb line) in one plane, the so-called plane of incidence. To fulfil this, the wavelength ''λ'' must be considerably greater than the distances between the scattering centres in the material.

{|
|-
|width="20px"|
|width="500px"| ''α'' = ''β'' or sin ''α'' = sin ''β''
|(1)
|}

The ultrasonic waves are altered at interfaces in terms of their wave propagation type (longitudinal or transverse wave), size or amplitude, and the direction and frequency of wave propagation ([[Dispersion|dispersion]] and mode conversion). The interface itself is formed by adjacent layers (e.g. metal or air with water) that have different characteristic impedances or acoustic impedances W or Z.

An incident sound wave is thus partially reflected at an interface and also partially transmitted or transferred to the neighbouring layer (overcoupling). The prerequisite for this is that both neighbouring layers have different sound impedances ''W'', whereby it is not the absolute value but the difference in sound impedances Δ''W'' that is decisive. In the general case, the volumes and thus the adjacent layer thicknesses are large compared to the wavelength ''λ'' of the ultrasound, which is why the sound propagation here depends only on the angle of incidence of the sound wave and the difference in sound impedances.

However, if the second medium is limited in thickness ''d'' in the direction of wave propagation (''d'' ≈ ''λ''), then the interface effectively doubles ([[Crack|cracks]], doublings and delaminations) and the behaviour of the sound waves then depends on the ratio of thickness to wavelength ''d''/''λ''.

The sound wave resistance or sound impedance of materials, as the product of [[Density|density]] ''ρ'' and [[Sound Velocity|sound velocity]] ''c'' with ''Z'' or ''W'' = ''ρ'' ''c'', is of particular importance for the reflection and [[Transmission Sound Waves|transmission behaviour]] of sound waves. This [[Material Parameter|parameter]] therefore describes the [[Elasticity|elastic]] material properties typical of the material, whereby [[Material & Werkstoff|materials]] with a high ''W'' value are described as sound-hard (Fe, Cu, Ni) and those with low ''W'' values (PMMA, Al, H2O) as sound-soft [1–4].

==Reflection of sound waves at interfaces==

When an ultrasonic wave enters from a sound-hard (''W''1) to a sound-soft (''W''2) medium or vice versa, reflection and transmission will occur, provided that the longitudinal wave strikes the interface between the two media perpendicularly ('''Fig. 1''').

[[File:Reflection_Sound-1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Reflection and [[Transmission Sound Waves|transmission]] at the interface between two media a) and between the [[Ultrasonic Sensors|ultrasonic sensor]] and the specimen surface b) with perpendicular sound incidence [9]
|}

The transmission content is greater when the differences between the sound impedances ''W''1 and ''W''2 are smaller. However, if the difference between ''W''1 and ''W''2 is very large, as is the case with a vacuum or air as the second medium, then a large to total content of the incident sound wave is reflected. This effect has a major influence on the detectability of [[Errors|defects]] in [[Ultrasound Testing|ultrasound testing technology]], both in the [[Pulse-Echo Ultrasonic Technique|pulse-echo ultrasonic technique]] and [[Transmission Sound Waves|transmission]] technique methods.

The reflection factor R ('''Eq. 2''') indicates how much of the incident [[Sound Pressure|sound pressure]] ''P''0 is reflected and how large the transmitted or passed content ''P''D is ('''Fig. 1a'''), whereby this [[Material Parameter|parameter]] depends significantly on the difference between the sound impedances ''W''1 and ''W''2 [4].

{|
|-
|width="20px"|
|width="500px"|<math>R=\frac{W_{2}-W_{1}}{W_{2}+W_{1}}</math>
|(2)
|}

When using longitudinal waves with vertical sensors, a large part of the sound waves can also be reflected at the [[Phase Boundary Surface|interface]] between the [[Ultrasonic Sensors|sensor]] and the workpiece if the [[Surface|surface]] is very rough and uneven and unsuitable coupling agents are used ('''Fig. 1b'''). This problem does not occur with the [[Ultrasonic Immersion Bath Technique|immersion bath]] and [[Squirter Technique|squirter techniques]] or when using [[Air-Ultrasound|air-ultrasound]]. However, since a part of the sound is always reflected back into the sensor depending on the sound impedances, the influence on the transmission signal (SE) must be minimised by using suitable damping layers [5–9]. 
By relating ''R'' to the [[Sound Pressure|sound pressure]] ''P'', this characteristic value can take on positive or negative values, whereby a negative sign for ''R'' (acoustically soft medium) indicates the reversal of the phase compared to the incident wave. When sound waves strike flat boundary surfaces perpendicularly, no wave conversion occurs, and for identical media (''W''1 = ''W''2), ''R'' = 0 and ''T'' or ''D'' = 1, i.e. there is unimpeded sound transmission.

[[File:Reflection_Sound-2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Reflection and [[Transmission Sound Waves|transmission]] at the interface between two media a) and between the [[Ultrasonic Sensors|ultrasonic sensor]] and the specimen surface b) with oblique sound incidence [9]
|}

If the ultrasound strikes oblique interfaces ('''Fig. 2'''), mode conversion or wave conversion, reflection, [[Transmission Sound Waves|transmission]] and [[Refraction Sound Waves|refraction]] occur in conjunction with frequency dispersion. Mode conversion is very important for some ultrasonic testing techniques, such as [[Ultrasonic Angle Beam Sensors|angle sensors]]. In this case, a transverse wave is additionally generated for both the reflected and transmitted waves. In the case of the angle sensor, depending on the difference in acoustic impedances and the angle of incidence, the longitudinal wave in medium 2 is totally reflected and the reflected transverse and longitudinal waves are attenuated in the sensor by an intermediate layer. In this case, the reflection factor ''R'' is calculated according to '''Eq. (3)''' as:

{|
|-
|width="20px"|
|width="500px"|<math>R=\frac{P_{R}}{P_{0}}=\sqrt{\frac{\frac{1}{4}[\frac{W_{1}}{W_{2}}-\frac{W_{2}}{W_{1}}]^{2} \sin ^{2}\frac{2\pi d}{\lambda}}{1+\frac{1}{4}[\frac{W_{1}}{W_{2}}-\frac{W_{2}}{W_{1}}]^{2} \sin ^{2}\frac{2\pi d}{\lambda}}}</math>
|(3)
|}

==Detectability of defects in ultrasound testing==

In ultrasonic defectoscopy, defects or discontinuities in the [[Material & Werkstoff|material]] are more easily detectable the greater the differences in sound waves (echo detectability) are (e.g. steel − air: ''R'' >> -1). On the other hand, thin layers of air already result in complete reflection of the ultrasonic wave at 1 MHz due to the large differences in ''W'', even with plane-parallel air gaps of 10 nm between the test sensor (steel) and a rough [[Surface|surface]] (air). In [[Pulse-Echo Ultrasonic Technique|pulse-echo ultrasonic technique]], the detection of the test piece thickness or the fault depth (voids, inclusions, delaminations, doublings or [[Crack|cracks]]) of discontinuities is based on the reflection of the pulsed transmitter pulse to the [[Ultrasonic Sensors|sensor]], which thus serves as both transmitter and receiver. A signal image ([[A-Scan Technique|A-scan]]) is generated from the measured time or path difference and displayed on a monitor. This A-scan (see: [[Imaging Ultrasonic Testing|imaging ultrasonic testing]]) shows the location and size of the [[Errors|defect]] in comparison to a substitute reflector (e.g. circular disc reflector). This normally allows defects (discontinuities) with a size of approx. 0.6 mm to be detected. If there are no defects, the wall thickness is determined on the basis of the rear wall echo (RE) or the defect location is indicated by total or partial reflection of the defect echo (FE) ('''Fig. 3'''). The [[Pulse-Echo Ultrasonic Technique|pulse-echo method]] can be used in [[Ultrasonic Standard Sensors|standard]], [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|transmitter-receiver (SE)]] and [[Ultrasonic Angle Beam Sensors|angle testing techniques]].

[[File:Reflection Sound-3.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px"|Pulse-echo ultrasonic method on a test piece with [[Errors|defect]] a) and [[A-Scan Technique|A-scan]] of the surface defect (imperfection) with partial coverage of the rear wall b) with perpendicular sound incidence [9]
|}

==See also==

* [[Refraction Sound Waves|Refraction sound waves]]
* [[Dispersion]]
* [[Transmission Sound Waves|Transmission sound waves]]
* [[Absorption Sound Waves|Absorption sound waves]]
* [[Sound Emission Experimental Conditions|Sound emission experimental conditions]]

==References==

{|
|-valign="top"
|[1]
|Krautkrämer, J., Krautkrämer, H.: Ultrasonic Testing of Materials. Springer, Berlin (1990) 4th Edition, (ISBN 978-3-540-51231-8)
|-valign="top"
|[2]
|Lerch, R., Sessler, G., Wolf, D.: Technische Akustik – Grundlagen und Anwendung. Springer, Berlin (2009) (ISBN 978-3-540-49833-9)
|-valign="top"
|[3]
|Möser, M.: Technische Akustik. Springer, Berlin (2015) (ISBN 978-3-662-47704-5)
|-valign="top"
|[4]
|Matthies, K. u. a.: Dickenmessung mit Ultraschall. DVS Media Verlag, Berlin (1998) 2nd Edition (ISBN 978-3-87155-940-2; see [[AMK-Library]] under M 44)
|-valign="top"
|[5]
|Šutilov, V. A.: Physik des Ultraschalls. Springer, Berlin (2013) p. 155 ff. (ISBN 978-3-70918-750-0)
|-valign="top"
|[6]
|Deutsch, M.; Platte, V.; Vogt, M.: Ultraschallprüfung. Grundlagen und industrielle Anwendungen. Springer, Berlin (1997) (ISBN 3-540-62072-9; see [[AMK-Library]] under M 45)
|-valign="top"
|[7]
|Steeb, S. (Eds.): Zerstörungsfreie Werkstück- und Werkstoffprüfung. Expert Publishing, Ehningen (1993), 2nd p. 253 (ISBN 3-8169-0964-7; see [[AMK-Library]] under M 42)
|-valign="top"
|[8]
|Busse, G.: Non-destructive Polymer Testing. In: [[Grellmann, Wolfgang|Grellmann, W.]], [[Seidler, Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 431–495 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-805-5; see [[AMK-Library]] under A 22)
|-valign="top"
|[9]
|[[Bierögel, Christian|Bierögel, C.]]: Lecture Notes: Materials Diagnostics – Hybrid Testing Methods. Vienna University of Technology (2015)
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

Ultrasonic Wall Thickness Measurement

2026-09-07T10:41:10Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Wanddickenmessung}}
{{PSM_Infobox}}
Ultrasonic wall thickness measurement
__FORCETOC__

==Technical requirements==

The most important practical applications of [[Ultrasound Testing|ultrasonic testing technology]] are the [[Non-destructive Testing (NDT)|non-destructive characterisation]] of [[Material & Werkstoff|materials]] for [[Errors|defect]] detection, [[Ultrasonic Weld Inspection|weld seam testing]] and the measurement of the thickness or wall thickness of [[Plastic Component|components]] [1], some of which require special testing technology for the testing application.

Ultrasonic wall thickness measurement is an established and industrially used testing method, which has been greatly simplified and improved in terms of measurement technology, particularly through digital technology, but still requires solid knowledge and practical experience on the part of the tester [1, 2].

For test objects that are not accessible from both sides, such as pipes or containers, which may also contain production media, wall thickness measurement is only possible using [[Non-destructive Polymer Testing|non-destructive polymer testing]] methods, whereby ultrasonic wall thickness measurement has become established here, regardless of the material. The [[Pulse-Echo Ultrasonic Technique|pulse-echo technique]] with [[Ultrasonic Standard Sensors|normal]] or [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|S/E sensor]] is particularly relevant from a technical point of view, although [[Ultrasonic Transmission Technique|ultrasonic transmission measurement technique]] is also applicable, but is preferred in laboratory operations and is used for [[Air-Ultrasound|air-ultrasound]].

==Physical fundamentals==

The test method for determining the wall thickness ''d'' is based on determining the sound running time ''t'' from the test head to the wall and back again, but requires knowledge of the longitudinal wave velocity ''c''L of the material to be tested at a specified test temperature ('''Eq. 1''').

{|
|- valign="top"
|width="350px"|<math>d=\frac{c_{L} \cdot t}{2}</math>
|width="50px"|(1)
|}

After converting '''Eq. (1)''', the [[Sound Velocity|sound velocity]] can then be determined from the known thickness of a test object, whereby calibration on identical material is required in both cases.

==Experimental methods and evaluation procedures==

The classic testing technique for wall thickness measurement uses either [[Pulse-Echo Ultrasonic Technique|ultrasonic pulse excitation]] with a defined pulse repetition frequency or quasi-stationary excitation of ultrasound using [[A-Scan Technique|A-scan]] display or the ''λ''/2 thickness resonance frequency ''f''R0 to determine thickness characteristics. While the resonance method is used in particular for very thin components, analogue and now digital [[A-Scan Technique|A-scan]] technique was previously the preferred method for industrial applications [1]. Simple wall thickness measurement using the single echo method is used especially for highly damping or scattering materials ('''Fig. 1a'''), as no multiple echoes are registered here. The runtime ''t'' of the ultrasound between the transmitted and reflected echoes (RE) from the back wall is evaluated on the monitor display, whereby influences from [[Adjustment|adjustment]], reading inaccuracy and echo height scaling can distort the measurement result.

[[File:US_Wall_Thickness-1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Ultrasonic wall thickness measurement using the pulse-echo technique as (a) single echo method and (b) multiple echo method
|}

In addition, there is the system dead time and, in the case of small thicknesses, overlaps between the high-voltage pulse of the transmitter and the first back wall echo (RE), which means that no foot point can be determined for the transmitted echo. If multiple [[Reflection Sound Waves|reflections]] occur between the [[Ultrasonic Sensors|ultrasonic sensors]] and the rear wall in homogeneous and isotropic materials, the multiple echo method ('''Fig. 1b''') can be used. In this case, the wall thickness is determined over several echoes, whereby the multiplication of the running path length must also be taken into account. One of the back wall echoes can then also be used as the starting point for the measurement. However, this preferred method can only be used when multiple echoes occur (homogeneous metallic materials) and is generally not usable in cases of high attenuation or strong scattering. For very thin walls and to suppress the transmission pulse, delay lines can also be used, which improve the close-range resolution and also allow applications on curved geometries (pipes or containers) [1–3]. In both cases, the measurement becomes much more complicated if there are corners and edges in the immediate vicinity of the measuring position [3, 4] and if there is severe erosive or corrosive damage to the rear wall. If [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|S/E sensors]] are used for wall thickness measurement to increase the local resolution, a correction of the reverse path length is necessary, as the ultrasound is transmitted into the test object at an angle corresponding to the roof angle. When using the [[Ultrasonic Immersion Bath Technique|immersion bath technique]] or delay line bodies, the respective interface echo (e.g. between the delay line and the test object surface) can also be included in the evaluation.

==FreqScan evaluation method==

Even when using the immersion technique, evaluation problems arise in wall thickness measurement with highly scattering composite materials, as the actual back wall echo is difficult to separate from the signal noise [5]. It can be seen that without the use of delay distances, a highly noisy back wall signal ('''Fig. 2 a''') occurs. With a delay line ('''Fig. 2b'''), there is a significant improvement in the signal-to-noise ratio, which can be further improved by using the FreqScan evaluation method developed by [https://de.wikipedia.org/wiki/Polymer_Service_Merseburg Polymer Service GmbH Merseburg] [6].

[[File:US_Wall_Thickness-2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Ultrasonic wall thickness measurement using the pulse-echo ultrasonic technique on GFRP (''d'' = 34.4 mm) in direct coupling as (a) without delay and (b) with delay [5]
|}

==Equipment technology for ultrasonic wall thickness measurement==

Compared to analogue measuring systems with [[A-Scan Technique|A-scan technique]], modern digital wall thickness devices are small and handy, and the wall thickness can be read directly from the integrated monitor. These devices ('''Fig. 3a''') simplify calibration, can be switched from thickness to sound velocity measurement and, in the case of [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|S/E sensors]], include correction of the path error, taking into account the respective roof angle. However, devices that include a digital display of the A-scan in addition to the alphanumeric display ('''Fig. 3b''') are preferable, as they allow the tester to check the [[Measured Value Accuracy|correctness of the measurement]]. Regardless of these advantages, the influences of coupling agent thickness, corrosion on the rear wall, fluctuating contact pressure or the test temperature must of course also be taken into account, whereby modern [[Ultrasonic Sensors|ultrasonic sensors]] often already have integrated temperature sensors [7].

[[File:US_Wanddickenmessung-3.jpg|500px]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px"|Digital ultrasonic wall thickness gauges (a) from [https://www.karldeutsch.de/?lang=en Karl Deutsch Prüf- und Messgeräte Bau GmbH und Co KG], Wuppertal and (b) from [https://ims.evidentscientific.com/en/flaw-detectors Olympus IMS]
|}

==Application examples==

Ultrasonic wall thickness measurement is used in the chemical industry to check wall thickness erosion, especially in pipelines, containers and tanks, as well as in shipbuilding for servicing purposes. This allows, for example, [[Surface|surface]] or selective corrosion (pitting), cavitation (voids) or erosion to be detected, differentiated and quantitatively specified.

[[File:US_Wall_Thickness-4.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 4''':
|width="600px"|Wall thickness measurement on metal and plastic pipes and use of the results for service life prediction
|}

In pipelines used in the chemical industry or in nuclear power plants, which form a significant part of the infrastructure, increased [[Material & Werkstoff|material]] wear is recorded, regardless of the material used, particularly in the impact area ('''Fig. 4''') at pipe curvatures or bends and in the vicinity of welded joints (flow turbulence) when abrasive or erosive media are transported. In the case of metallic pipes, erosion or corrosive effects often occur here, while in the case of plastic pipes or containers, damage to the inliner occurs, which leads to exposure of the [[Fibre-reinforced Plastics#Types of reinforcing plastics|reinforcing fibre]] and a reduction in the initial wall thickness ''d''0 (see '''Fig. 4'''). With prescribed cyclical inspection (3 to 6 months) of the residual wall thickness, these pipe sections can be replaced prophylactically if the permissible residual wall thickness ''d''zul is known, thereby avoiding any consequential damage. If these measuring positions are difficult to access due to design conditions and/or thermal insulation, these [[Ultrasonic Sensors|ultrasonic sensors]] can also be installed in a stationary manner, analogous to the acoustic emission sensor technology used in nuclear power plants, and the wall thickness is determined permanently or cyclically at an identical position [8].

A special form of thickness measurement is the determination of the layer thicknesses of paint coatings or plastic insulation on metallic base materials using ultrasound, which, however, requires a special measurement and evaluation methodology [3].

==See also==

* [[Acoustic Properties|Acoustic properties]]
* [[Ultrasound Modulation|Ultrasound modulation]]
* [[Air-Ultrasound − Device Technology|Air-Ultrasound − Device technology]]
* [[HF-Scan|HF-scan]]
* [[Sound Pressure|Sound pressure]]

==References==

{|
|-valign="top"
|[1]
|Matthies, K. u. a.: Dickenmessung mit Ultraschall. DVS-Verlag GmbH, Berlin, 2nd Edition (1998), (ISBN 3-87155-940-7; see [[AMK-Library]] under M 44)
|-valign="top"
|[2]
|Deutsch, V., Platte, M., Vogt, M.: Ultraschallprüfung – Grundlagen und industrielle Anwendungen. Springer, Berlin (2012), (ISBN 978-3-642-63864-0; see [[AMK-Library]] under M 45)
|-valign="top"
|[3]
|Gevatter, H.-J., Grünhaupt, U. (Eds.): Handbuch der Mess- und Automatisierungstechnik in der Produktion. Springer, Berlin, 2nd Edition (2006), (ISBN 978-3-540-21207-2)
|-valign="top"
|[4]
|DIN EN 14127 (2011-04): Non-destructive Testing – Ultrasonic Thickness Measurement (withdrawn; replaced by DIN EN ISO 16809 (2025-09)
|-valign="top"
|[5]
|Sirch, C., Oluschinski, A., [[Bierögel, Christian|Bierögel, C.]], [[Grellmann, Wolfgang|Grellmann, W.]]: Ultraschallprüfung von Kunststoffbauteilen. 12. Tagung „Problemseminar Deformation und Bruchverhalten von Kunststoffen“, Merseburg, June 24–26, 2009, Proceedings CD-ROM
|-valign="top"
|[6]
|Sirch, C., Oluschinski, A., Bierögel, C., Rufke, B., zur Horst-Meyer, S., [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.]: Ultraschall-Messungen an Grenzflächen in GfK-Thermoplast-Verbunden. 11. Tagung „Problemseminar Deformation und Bruchverhalten von Kunststoffen“, Merseburg, June 20–22, 2007, Proceedigs CD-ROM (ISBN 978-3-86010-918-2) pp. 429−430
|-valign="top"
|[7]
|zur Horst-Meyer, S.: SONOWALL – Wanddickenmessungen mit Ultraschall. DGZfP-Jahrestagung „Zerstörungsfreie Werkstoffprüfung“ (2010), Erfurt, P54 [http://jt2010.dgzfp.de/Portals/jt2010/BB/p54.pdf Download as pdf]
|-valign="top"
|[8]
|Mück, A., Imhof, D.: Dauerüberwachung der Wanddicke von Rohrleitungen mit Ultraschall. DGZfP-Jahrestagung „Zerstörungsfreie Werkstoffprüfung“ (2015), Salzburg, Österreich, A1
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

File:SE-Probes Fig2.jpg

2026-09-07T10:40:47Z

Oluschinski:

File:SE-Probes Fig1.jpg

2026-09-07T10:40:40Z

Oluschinski:

Ultrasonic Transmitter(S)-Receiver(E) Sensors

2026-09-07T10:40:17Z

Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Sende(S)-Empfänger(E)-Prüfköpfe}} {{PSM_Infobox}} Ultrasonic transmitter(S)-receiver(E) sensors __FORCETOC__ ==General information== Ultrasonic S/E sensors, also known as transmitter/receiver sensors, consist of a transmitter unit and a receiver unit that are electrically and vibrationally separated, i.e. separate Piezoelectric Ceramic Transducer|piezoelectric transd..."

{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Sende(S)-Empfänger(E)-Prüfköpfe}}
{{PSM_Infobox}}
Ultrasonic transmitter(S)-receiver(E) sensors
__FORCETOC__

==General information==

Ultrasonic S/E sensors, also known as transmitter/receiver sensors, consist of a transmitter unit and a receiver unit that are electrically and vibrationally separated, i.e. separate [[Piezoelectric Ceramic Transducer|piezoelectric transducers]]. Such sensors are used when, due to the low thickness of the test piece or surface imperfections, the close-up resolution of the [[Ultrasonic Standard Sensors|standard sensor]] is insufficient even at increased frequencies or when using a delay line, i.e. the back wall or defect echoes cannot be separated from the transmission pulse in time. These sensors therefore contain two electrically and acoustically decoupled [[Ultrasonic Standard Sensors|standard sensors]] in one housing, resulting in a combination of the [[Ultrasonic Transmission Technique|transmission]] and [[Pulse-Echo Ultrasonic Technique|pulse-echo methods]] for measurement purposes.

==Schematic setup of an S/E sensor==

Due to the necessary dual-channel design of the ultrasonic measuring system, the transmission pulse does not overlap with the reception echo in the display. This allows defects located just below the [[Surface|surface]] of the test piece to be detected or very accurate results to be achieved in wall thickness measurement [1, 2].

The two transducers, which operate continuously in the transmit or receive modes, are inclined at a certain angle to the normal or separation plane, which is referred to as the roof angle β ('''Fig. 1'''). Depending on the roof angle implemented, inclined delay lines of length l are glued under the [[Piezoelectric Ceramic Transducer|transducers]], resulting in maximum sensitivity in a specified depth range [1].

[[File:SE-Probes_Fig1.jpg|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Schematic arrangement of an ultrasonic S/E sensor
|}

The delay lines correspond to wedges made of [[Plastics|plastics]] with good sound conductivity, such as polymethyl methacrylate ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: PMMA) or polystyrene ([[Plastics – Symbols and Abbreviated Terms|abbreviation]]: PS). An [[Acoustic Properties|acoustic adaptation layer]] is usually installed between the [[Piezoelectric Ceramic Transducer|transducer]] and the attachment wedge. Its thickness corresponds to the quarter wavelength (''λ''/4) of the sensor, and serves in particular to adapt the impedance and optimise sound transmission between the transducer and the delay line on the transmitter and receiver side. In addition to a low reflection factor, a suitable damping body also provides high mechanical and acoustic damping of the S/E sensor [3]. If the transducers or delay wedges are only inclined by an angle β, these are referred to as [[Ultrasonic Standard Sensors|standard S/E sensors]]. If the transducers are additionally inclined by an angle γ (γ > β) in the 90° plane, then an angle S/E sensor is present, with which transverse waves can be generated in the test object. The conditions and statements defined under the term [[Ultrasonic Angle Beam Sensors|angle beam sensor]] apply to the angle ''γ''.

The application or working range of S/E sensors is in the test piece area where the sound fields of the transmitter (S) and receiver (E) overlap ('''Fig. 2''')

[[File:SE-Probes_Fig2.jpg|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Sound field of the ultrasonic S/E sensor (a) with large and small roof angle ''β'' and (b) sensitivity–distance diagram
|}

As can be seen in '''Fig. 2a''', the near-field resolution can be varied over a wide range by selecting the roof angle, the distance between the transmitter and receiver, and the length of the delay wedge, although this also affects the dead zone of the sensor. The sensitivity therefore varies with the path of the ultrasound l and can be represented graphically in the diagram corresponding to '''Fig. 2b'''. The dark red field marks the zone of maximum sensitivity, and the light red triangle marks the working range. With large roof angles, the ultrasound is already inclined and not perpendicular to the [[Surface|surface]] due to the design. As a result, an increase in the roof angle causes a so-called detour error, which is reflected in an increase in the transit time and thus, for example, in an error in the [[Ultrasonic Wall Thickness Measurement|wall thickness measurement]]. This error can be compensated for by [[Adjustment|adjusting]] the ultrasonic system or mathematically in digital devices.

In addition to the roof angle, the test frequency, the type and shape of the oscillator, the dimensions of the oscillator and the attachment wedge, and the distance between the transmitter and receiver also influence the quality and reliability of the test result [2, 4, 5].

==Examples of S/E sensor designs==

Examples of different S/E sensors are shown in '''Fig. 3''', where you can see the separate connections for the transmitter and receiver.

[[File:S_E_Pruefkoepfe-3.JPG|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px"|Examples of S/E test sensors (handheld test sensors) of different sizes and frequencies (a) from GE Measurement & Control Solutions, Alzenau, and (b) from GAZ-Prüftechnik GmbH, Alpen
|}

==See also==

* [[Ultrasound Testing|Ultrasound testing]]
* [[Ultrasonic Direct Coupling|Ultrasonic direct coupling]]
* [[Ultrasonic Composite Sensors|Ultrasonic composite sensors]]
* [[Ultrasonic Weld Inspection|Ultrasonic weld inspection]]
* [[Ultrasonic Standard Sensors|Ultrasonic standard sensors]]

==References==

{|
|-valign="top"
|[1]
|Steeb, S.: Zerstörungsfreie Werkstoffstück- und Werkstoffprüfung. 5th Edition, Expert Verlag, Renningen (2016), (ISBN 978-3-81693-261-1); 2nd Edition (1993) (ISBN 3-8169-0964-7; see [[AMK-Library]] under M 41)
|-valign="top"
|[2]
|Matthies, K.: Dickenmessung mit Ultraschall. DVS-Verlag GmbH, Berlin, 2nd Edition, (1998), (ISBN 3-87155-940-7; see [[AMK-Library]] under M 44)
|-valign="top"
|[3]
|Deutsch, V., Platte, M., Vogt, M.: Ultraschallprüfung – Grundlagen und industrielle Anwendungen. Springer, Berlin (1997), (ISBN 3-540-62072-9; see [[AMK-Library]] under M 45)
|-valign="top"
|[4]
|Schuster, V., Lach, M., Platte, M.: Die Qual der Wahl: Welcher Prüfkopf für welchen Einsatz. DGZfP-Jahrestagung „Zerstörungsfreie Werkstoffprüfung“ (2004), Salzburg, Österreich, Sonderdruck Karl Deutsch, SD 1/51
|-valign="top"
|[5]
|Krautkrämer, J.; Krautkrämer, H.: Werkstoffprüfung mit Ultraschall. Springer, Berlin Heidelberg (2013) p. 43 (ISBN 978-3-662-10910-6)
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

Ultrasonic Transmission Technique

2026-09-07T10:39:55Z

Oluschinski:

{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Durchschallungs-Technik}}
{{PSM_Infobox}}
Ultrasonic transmission technique
__FORCETOC__

==Requirements for ultrasonic transmission technique==

Non-destructive [[Ultrasound Testing|ultrasonic testing technology]] is divided into two main classic testing methods, known as transmission and reflection methods or [[Pulse-Echo Ultrasonic Technique|pulse-echo technology]] [1].
Regardless of whether the ultrasound is transmitted into the [[Material & Werkstoff|material]] via [[Ultrasonic Direct Coupling|direct coupling]], [[Ultrasonic Immersion Bath Technique|immersion technology]] or [[Air-Ultrasound|air-ultrasound]], and regardless of the type of ultrasonic probe ([[Ultrasonic Standard Sensors|standard]], [[Ultrasonic Angle Beam Sensor|angle]] or [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|S/E]] sensor) used, the transmission method or intensity method generally requires two sensors of the same design with identical properties. In addition, it must be ensured that the same coupling medium, thickness ''d'', is used and that the acoustic axes of the opposing [[Ultrasonic Standard Sensors|standard sensors]] are ideally aligned with each other. The transmission method can be performed using standard, angle and S/E sensors and offers the advantage that in the case of materials with high sound attenuation, only the simple sound path between the transmitter and receiver needs to be covered.

==Options for coupling==

The transmission method with standard sensors generally also uses pulsed ultrasound with a specified pulse repetition frequency. [[Ultrasonic Direct Coupling|Ultrasonic direct coupling]] can be achieved using special oils or greases, [[Air-Ultrasound|air-ultrasound]] or the immersion bath technique using [[Squirter Technique|Squirter technique]] ('''Fig. 1'''). Due to the fact that the test object must be accessible from both sides for this test method to be used, the procedure is mainly used in laboratories in practice.

[[File:Ultraschall-Durchschallungs-Technik-1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Schematic presentation of the ultrasonic transmission technique with [[Ultrasonic Standard Sensors|standard sensors]] (a) for [[Ultrasonic Direct Coupling|direct coupling]], (b) using [[Air-Ultrasound|air-ultrasound]], and (c) using the [[Ultrasonic Immersion Bath Technique|immersion bath technique]]
|}

==Schematic representation of miscouplings==

In all three cases, the acoustic axis of the sensors must be perfectly aligned and must not be tilted, as this would reduce the intensity of the received ultrasound. Misalignment of the [[Ultrasonic Sensors|sensors]] and coupling errors due to varying coupling layer thicknesses can sometimes cause significant errors ('''Fig. 2'''). Transmission testing does not provide any information about the type and depth of existing discontinuities, only about the extent of defects perpendicular to the incident ultrasound [1, 2], whereby different positions of the defects (delaminations or doublings) can also result in different conclusions. Compared to an ideal sensor position, the defects shown in '''Fig. 2''' all cause a reduction in intensity at the receiver sensor.

[[File:Ultraschall-Durchschallungs-Technik-2.jpg|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Schematic representation of miscoupling in the transmission method with standard sensors (a) incorrect acoustic axis, (b) differing coupling layer thickness, and (c) tilting of the sensor
|}

==Detection of material defects==

A defect-free and homogeneous test piece according to '''Fig. 3a''' produces a reduction in intensity from ''I''0 to ''I'' in accordance with the attenuation of the [[Material & Werkstoff|material]] being examined. The evaluation of the runtime ''t'' allows the wall thickness of the test object in question to be determined if the speed ''c''L of the longitudinal wave is known. If there are flat defects in the direction of sound propagation, these can shield the received signal completely ('''Fig. 3b''') or partially ('''Fig. 3c'''), depending on their size and position. The porosities in '''Fig. 3d''' cause a strong reduction in intensity due to scattering effects.

[[File:US-Trans-Technique-3.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px"|Schematic presentation of [[A-Scan Technique|A-scans]] in the transmission method with standard sensors with (a) ideal transmission, (b) total coverage of the back-wall echo (RE), (c) partial coverage of the backwall echo, and (d) intensity reduction due to porosity
|}

The transmission method can also be performed with [[Ultrasonic Angle Beam Sensors|angle beam sensors]] and can be used to detect planar defects, such as doublings in sheet metal or delaminations in laminates. This requires angle sensors with suitable incidence angles for the respective [[Material & Werkstoff|material]] type, in which transverse waves (see: [[Refraction Sound Waves|refraction sound waves]] and [[Ultrasonic Waves Reflection|ultrasonic waves reflection]]) are used for [[Non-destructive Testing (NDT)|non-destructive testing]]. Since the [[Sound Emission|sound emission]] is transmitted at a defined angle, the sound path to the receiver is longer than with perpendicular transmission using a standard sensor ('''Fig. 4'''). In '''Fig. 4a''', it can be seen that in the case of no defects, the backwall is displayed by the receiver signal. With an identical angle of incidence, the distance between the two sensors must be reduced in order to detect the horizontal [[Errors|defect]], which is achieved using the so-called tandem technique (see '''Fig. 4b'''). Due to the shorter sound path in the case of a horizontal defect, the intensity of the defect echo (FE) is higher than that of the backwall echo (RE). '''Figure 4b''' shows that the defect depth of the vertical discontinuity influences the head distance of the tandem and that this must be varied during the measurement.

[[File:US-Trans-Technique-4.jpg|550px]]
{|
|- valign="top"
|width="50px"|'''Fig. 4''':
|width="600px"|Schematic representation of [[A-Scan Technique|A-scans]] in the ultrasonic testing method with [[Ultrasonic Angle Beam Sensors|angle sensors]] for (a) test objects with and without horizontal defects and (b) test objects with vertical defects of varying depths using the tandem technique
|}

Due to the specific design, the [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|S/E sensors]] are also operated in transmission mode. The usable depth or thickness range of the test object or the suspected defect location is determined by the roof angle of the test sensor pair and results from the superposition of the sound fields of the two transducers, the [[Sound Velocity|sound velocity]] of the test medium and the focusing of the sound beams. With this type of sensors, a so-called detour error always occurs, which is caused by the sound field properties and the roof angle and can be taken into account by making [[Adjustment|adjustments]] [2].

==See also==

* [[Ultrasound – Elastic Parameters|Ultrasonic – Elastic parameters]]
* [[Ultrasonic Birefringence|Ultrasonic birefringence]]
* [[Ultrasonic Modulation|Ultrasonic modulation]]
* [[Ultrasonic Phased Array Sensors|Ultrasonic phased array sensors]]
* [[Ultrasonic Composite Sensors|Ultrasonic composite sensors]]

==References==

{|
|-valign="top"
|[1]
|Deutsch, V., Platte, M., Vogt, M.: Ultraschallprüfung – Grundlagen und industrielle Anwendungen. Springer, Berlin (2012), (ISBN 978-3-642-63864-0; see [[AMK-Library]] under M 45)
|-valign="top"
|[2]
|Matthies, K.: Dickenmessung mit Ultraschall. DVS Media GmbH, Berlin, 2nd Edition, (1998), (ISBN 3-87155-940-7; see [[AMK-Library]] under M 44)
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

File:TOFD-2.jpg

2026-09-07T10:39:23Z

Oluschinski:

File:TOFD-Fig1.jpg

2026-09-07T10:39:09Z

Oluschinski:

Ultrasonic Time-of-Flight Diffraction (TOFD) Technique

2026-09-07T10:38:42Z

Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Laufzeit-Beugungsverfahren (TOFD)}} {{PSM_Infobox}} Ultrasonic time-of-diffraction (TOFD) technique __FORCETOC__ ==General== The time-of-flight diffraction (TOFD) method is an ultrasonic measurement method used in particular to test steel components for cracks and volume defects. It is used for quality control of Ultrasonic Weld Inspecti..."

{{Language_sel|LANG=ger|ARTIKEL=Ultraschall-Laufzeit-Beugungsverfahren (TOFD)}}
{{PSM_Infobox}}
Ultrasonic time-of-diffraction (TOFD) technique
__FORCETOC__

==General==

The time-of-flight diffraction (TOFD) method is an [[Ultrasound Testing|ultrasonic measurement method]] used in particular to test steel components for [[Crack|cracks]] and volume defects. It is used for quality control of [[Ultrasonic Weld Inspection|weld seams]] both in outgoing goods inspection and in field tests on [[Plastic Component|components]] during operation. A special feature of this method is the presentation of the test result, which allows the depth and geometry of the defect to be determined immediately. Although this testing technique is also suitable for [[Plastics|plastics]] in principle, no publications on this subject are known in the technical literature to date.

==Measurement setup==

Two identical [[Ultrasonic Angle Beam Sensors|angle beam sensors]] are used, which are aligned with each other in such a way that the sound fields of the sensors overlap in the component volume, allowing all potential defects to be ‘illuminated’ ('''Fig. 1'''). The ultrasonic transducers are shown in '''Fig. 1''' as [[Ultrasonic Standard Sensors|standard sensors]] glued onto lead wedges. In special angle sensors, this design is arranged in a housing. The angle of incidence requires a corresponding distance between the sensors in order to be able to sound through the test sample volume. In addition to the angle of incidence, this distance depends on the structure of the sound field, which is determined by the combination of transducer and damping body, but also on the sound path in the lead-in distance that realises the angle of incidence.

[[File:TOFD-Fig1.jpg|450px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Principle diagram of the TOFD method [1]
|}

==Functionality==

The measuring method works according to the [[Ultrasonic Transmission Technique|transmission principle]], i.e. one angle sensor transmits the sound (transmitter) and the other receives the sound waves reflected in the volume (receiver). Since the two sensors are aligned so that the reflection signal (back-wall reflection) can be registered by the receiving sensor, this signal limits the measuring range on the time axis upwards (HF images in '''Fig. 1''' below). The lower limit of the measuring range is marked by the lateral waves, whose [[Sound Velocity|sound velocity]] corresponds to that of the longitudinal waves.

The measuring range of the method, in which defects can be detected, lies between these two limits. As is known from wave optics, [[Crack|cracks]], delaminations and discontinuities represent diffraction obstacles and starting points for elementary waves. These sound waves can be registered by the receiver and displayed in the [[HF-Scan|HF-scan]]. As an example, '''Fig. 1''' shows a volume crack running vertically through the tested weld seam.

==Evaluation==

The TOFD measurement signal shown in '''Fig. 1''', which is recorded from a weld seam, is usually recorded with simultaneous indication of the path information. For this purpose, both [[Ultrasonic Sensors|ultrasonic test sensors]] are connected to each other at a fixed distance and moved parallel to the weld seam on a trolley with an incremental encoder (tandem arrangement). This results in a three-dimensional (‘transmission’) image with the representation of the time axis (vertical) and the distance travelled or the horizontal position with a grey value coding of the peak amplitudes ('''Fig. 2''').

[[File:TOFD-2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|Example of a three-dimensional TOFD measurement signal [2]
|}

The lateral wave and the reflected back-wall signal in '''Fig. 2''' represent the boundaries of the TOFD image. Between these two signals, the diffraction signal originating from a material defect can be seen in the right half of the image. If the geometries and the angles of incidence are known, the defect depths can then be calculated.

==Summary==

The ultrasonic time-of-flight diffraction technique is a testing method used to determine the condition of weld seams both qualitatively and quantitatively. It can be used to determine the geometry and size of defects in welds. This method is also suitable for assessing corrosion in pipes [3] and is standardised for other applications in [[Non-destructive Testing (NDT)|non-destructive testing]] [4–7].

==See also==

* [[Imaging Ultrasonic Testing|Imaging ultrasonic testing]]
* [[Ultrasonic Composite Sensors|Ultrasonic composite sensors]]
* [[Ultrasonic Direct Coupling|Ultrasonic direct coupling]]
* [[Ultrasound – Elastic Parameters|Ultrasound – Elastic parameters]]
* [[Ultrasonic Phased Array Sensors|Ultrasonic phased array sensors]]
* [[Ultrasonic Transmitter(S)-Receiver(E) Sensors|Ultrasonic transmitter(S)-receiver(E) sensors]]

==References==

{|
|-valign="top"
|[1]
|https://www.olympus-ims.com/de/ultrasonic-transducers/tofd/ (access on January 26, 2026)
|-valign="top"
|[2]
|http://www.autsolutions.net/ndt-resources/tofd/ (access on January 26, 2026)
|-valign="top"
|[3]
|Spies, M., Dillhöfer, A., Müller, W., Rieder, H., Schmitz, V.: [https://www.ndt.net/search/docs.php3?id=15601 SAFT, TOFD, Phased Array – Klassische Anwendungen und neuere Entwicklungen der Ultraschall-Bildgebung]. Seminar des Fachausschusses Ultraschallprüfung der DGZfP (DGZfP UT 2013)
|-valign="top"
|[4]
|ISO 16828 (2025-07): Non-destructive Testing – Ultrasonic Testing – Time-of-Flight Diffraction Technique for Detection and Sizing of Discontinuities
|-valign="top"
||[5]
|ISO 10863 (2020-09): Non-destructive Testing of Welds – Ultrasonic Testing – Use of Time-of-Flight Diffraction Technique (TOFD)
|-valign="top"
|[6]
|DIN EN 583-6 (2009-03): Non-destructive Testing – Ultrasonic Examination – Part 6: Time-of-Flight Diffraction Technique as a Method for Detection and Sizing Discontinuities (wthdrawn; replaced by DIN EN ISO 16828 (2025-07))
|-valign="top"
|[7]
|ISO 15626 (2018-07): Non-destructive Testing of Welds – Time-of-Flight Diffraction Technique (TOFD) – Acceptance Levels
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

File:US Standard Sensors-Fig6.jpg

2026-09-07T10:38:18Z

Oluschinski:

File:US Standard Sensors-Fig5.jpg

2026-09-07T10:38:10Z

Oluschinski: