Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Zugfestigkeit}} {{PSM_Infobox}} Tensile strength FORCETOC ==Definition of tensile strength== In conventional tensile tests on plastics, stress and strain-related characteristic values are determined in accordance with ISO 527-1, whereby the material parameters correspond to selected point..."

2025-12-08T06:17:48Z

Created page with "{{Language_sel|LANG=ger|ARTIKEL=Zugfestigkeit}} {{PSM_Infobox}} Tensile strength __FORCETOC__ ==Definition of tensile strength== In conventional tensile tests on plastics, stress and strain-related characteristic values are determined in accordance with ISO 527-1, whereby the material parameters correspond to selected point..."

New page

{{Language_sel|LANG=ger|ARTIKEL=Zugfestigkeit}}
{{PSM_Infobox}}
Tensile strength
__FORCETOC__

==Definition of tensile strength==

In conventional [[Tensile Test | tensile tests]] on [[Plastics | plastics]], [[Stress | stress]] and strain-related [[Material Value | characteristic values]] are determined in accordance with ISO 527-1, whereby the [[Material Parameter | material parameters]] correspond to selected points on the stress–strain diagram. By definition, the tensile strength ''σ''m or ''σ''M corresponds to the stress value on the vertical axis of the ''σ''–''ε'' diagram at the first stress maximum during the [[Tensile Test | tensile test]] and is calculated according to Eq. (1) [1].

{|
|-
|width="20px"|
|width="500px" | <math>\sigma _{m}=\frac{F_{m}}{A_{0}}=\frac{F_{max}}{A_{0}}</math>
|width="50px" |(1)
|}

Depending on the type of diagram (a to d) of the plastic being tested, the tensile strength ''σ''m can be identical to the [[Yield Stress | yield stress]] ''σ''y or the tensile stress at breaking ''σ''b ('''Fig. 1'''). Although the tensile stress at break is specified as a parameter in the standard, this value should not be used as a comparative parameter for plastics, as it is highly dependent on the switch-off criterion of the [[Material Testing Machine | material testing machine]].

==Strain at tensile strength and tensile strain at break==

The associated [[Material Value | characteristic value]] on the horizontal axis marks the location where the first maximum occurs and is referred to as the strain of the tensile strength or, better, the yield strain ''ε''m. This characteristic value can also correspond to the tensile strain at yield ''ε''y or the tensile strain at break ''ε''b. In principle, the strain up to the yield strength ''ε''y (diagrams b and c in '''Fig. 1''') must be measured with [[Strain Gauge | strain gauges]] as a normative value or, in the case of diagrams without yield strength up to break (diagrams a and d in '''Fig. 1'''), also determined using clip-on extensometers (see: [[Tensile Test#Tensile test, path measurement technique|tensile test, path measurement technique]]).

{|
|-
|width="20px"|
|width="500px" | <math>\varepsilon _{t}= \varepsilon _{y}+\frac{\Delta L_{t}}{L}</math>
|width="50px" |(2)
|}

[[file:Zugfest_1.jpg|500px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Typical stress–strain curves and associated parameters in the tensile test [1]
|}

The [[Material Value | characteristic values]] tensile stress at break or strain at tensile strength are determined for diagram types b and c from the sum of the normative strain up to the yield point and the subsequent nominal strain from the traverse path according to equation (2). ''L'' is the clamp distance and ''L''t corresponds to the extension Δ''L'' or the increase in the distance between the clamping clamps. The normative strain, which is always determined as a deformation measured directly on the test [[Specimen | specimen]], is calculated according to Eq. (3). ''L''0 is the initial distance of the strain sensor on the test specimen and ''L''0 is the measured extension of the sensor distance. The strain can be specified dimensionless (Eqs. (2) and (3)) or as a percentage when multiplied by a factor of 100.

{|
|-
|width="20px"|
|width="500px" | <math>\varepsilon = \frac{\Delta L_{0}}{L_{0}}</math>
|width="50px" |(3)
|}

==Stress–strain diagram for PA6==

The evaluation according to the standard [1] is difficult if a stress–strain diagram is determined in the [[Tensile Test | tensile test]], e.g. for PA 6 according to '''Fig. 2'''. Due to the definition that the tensile strength corresponds to the first stress maximum, the absolute maximum according to this standard cannot be assigned a [[Material Parameter | parameter]], as all parameters have already been assigned. In contrast to the usual evaluation procedure of [[Material Testing Machine | testing machine]] manufacturers and a previous revision of this standard [2], the absolute maximum is designated here as tensile strength ''σ''m and the relative maximum only as [[Yield Stress | yield stress]] ''σ''y. The definition of tensile strength here was that this is the maximum stress that the test [[Specimen | specimen]] can withstand during the [[Tensile Test | tensile test]].

[[file:Zugfest_2.jpg|500px]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px" |Nominal and normative strain of a [[Specimen | test specimen]] in the [[Tensile Test | tensile test]]
|}

The tensile strength depends very much on the [[Test Speed | test speed]] and the test temperature, and is only comparable for different materials under identical test conditions and test [[Specimen | specimens]].

A comprehensive literature analysis of the mechanical properties of the ''E''t, ''σ''M and ''ε''B tensile test is compiled for numerous [[Plastics | plastics]] in [3].

==See also==

* [[Tensile Test | Tensile test]]
* [[Tensile Test Uniform Elongation|Tensile test uniform elongation]]
* [[Yield Stress | Yield stress]]
* [[Crosshead Speed | Crosshead speed]]
* [[Test Speed | Test speed]]
* [[Material Testing Machine | Material testing machine]]

'''Reference'''

{|
|-valign="top"
|[1]
|ISO 527-1 (2019-07): Plastics – Determination of Tensile Properties – Part 1: General Principles
|-valign="top"
|[2]
|ISO 527-1 (1993-06): Plastics – Determination of Tensile Properties – Part 1: General Principles
|-valign="top"
|[3]
|[[Bierögel, Christian|Bierögel, C.]], [[Grellmann, Wolfgang|Grellmann, W.]]: Quasi-Static Tensile Test. In: [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.], [[Seidler, Sabine|Seidler, S.]]: Mechanical and Thermomechanical Properties of Polymers. Landolt-Börnstein, Volume VIII/6A3, Springer Berlin (2014) 76–143, (ISBN 978-3-642-55165-9; see [[AMK-Büchersammlung | AMK-Library]] under A 16) DOI: [http://dx.doi.org/10.1007/978-3-642-55166-6_16 http://dx.doi.org/10.1007/978-3-642-55166-6_16]
|}

[[Category:Tensile Test]]

Tensile Strength - Revision history