Oluschinski at 13:21, 12 December 2025

2025-12-12T13:21:28Z

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	<span style="font-size:1.2em;font-weight:bold;">~~Signal sources and signal processing~~</span>		<span style="font-size:1.2em;font-weight:bold;">Sound emission testing</span>
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	* [[Sound Emission\|Sound emission]]		* [[Sound Emission\|Sound emission]]
	* [[Sound Analysis\|Sound analysis]]		* [[Sound Emission Analysis\|Sound emission analysis]]
	* [[Sound Emission Experimental Conditions\|Sound emission experimental conditions]]		* [[Sound Emission Experimental Conditions\|Sound emission experimental conditions]]
	* [[Ultrasonic Birefringence\|Ultrasonic birefringence]]		* [[Ultrasonic Birefringence\|Ultrasonic birefringence]]

Oluschinski: Created page with "{{Language_sel|LANG=ger|ARTIKEL=Schallemissionsprüfung}} {{PSM_Infobox}} Signal sources and signal processing FORCETOC ==Signal sources and signal processing== Sound emission testing is a quasi-non-destructive testing method that is linked to damage-inducing processes. The sound emissions released in the process can be caused by mechanical, biological or c..."

2025-12-05T13:34:06Z

Created page with "{{Language_sel|LANG=ger|ARTIKEL=Schallemissionsprüfung}} {{PSM_Infobox}} Signal sources and signal processing __FORCETOC__ ==Signal sources and signal processing== Sound emission testing is a quasi-non-destructive testing method that is linked to damage-inducing processes. The sound emissions released in the process can be caused by mechanical, biological or c..."

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{{Language_sel|LANG=ger|ARTIKEL=Schallemissionsprüfung}}
{{PSM_Infobox}}
Signal sources and signal processing
__FORCETOC__

==Signal sources and signal processing==

Sound emission testing is a quasi-[[Non-destructive Polymer Testing|non-destructive testing method]] that is linked to damage-inducing processes. The [[Sound Emission|sound emissions]] released in the process can be caused by mechanical, biological or chemical [[Stress|stresses]] in both the microscopic and macroscopic range. The definition of [[Sound Emission|sound emissions]] according to Bardenheier, who states in [1]:

''‘Sound emissions (SE) occur in every solid whenever elastic energy is released in the form of mechanical stress waves when certain material stresses are exceeded.’''

The mechanical stress waves propagate spherically from the source and can be converted into analogue electrical signals using [[Piezoelectric Ceramic Transducer|piezoelectric transducers]] (SE sensors). However, the original signal, which can be defined as a square wave, undergoes significant changes due to [[Dispersion|dispersion]] and [[Reflection Sound Waves|reflections]] as it propagates through the [[Material & Werkstoff|material]]. The square wave can thus become a long, slowly rising and falling signal, which also exhibits an exponential decrease due to inherent loss mechanisms. '''Figure 1''' schematically shows the signal processing in [[Sound Emission Analysis|sound emission analysis]] (SEA).

[[File:Sound Emission Testing-1.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Signal processing in sound emission analysis based on [1]
|}

==Continuous emissions and burst signals==

The recorded signals can basically be classified into two types. DIN EN 1330-9 [2] defines a signal that cannot be separated despite high time resolution as a continuous [[Acoustic Emission|emission]] and events that can be separated from each other as burst emissions or transient signals. Characteristic examples of continuous emissions are [[Deformation#Plastic deformation|plastic]], homogeneous deformations of metals, leakage flows or flow processes. Discontinuous events such as [[Crack Formation|crack formation]] and [[Crack Propagation|crack propagation]] processes, as well as fibre pull-out and fibre breakage in [[Fibre-reinforced Plastics|fibre-reinforced plastics]], lead to burst emissions. (see: [[Fracture Behaviour#Fracture behaviour, short fibre composites|fracture behaviour, short fibre composites]]).

==Principle of sound emission testing==

'''Figure 2''' on the left shows a schematic representation of the principle of acoustic emission measurement using a measuring chain consisting of an [[Ultrasonic Sensors|ultrasonic sensor]], a preamplifier and an analyser. A typical transient signal with the derivable [[Measured Variable|measured variables]] is shown in the right-hand '''Fig. 2b'''.

[[File:Sound Emission Testing-2.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px" |Principle of sound emission measurement (a) and example of a transient signal with the characteristic [[Measured Variable|measured variables]] that can be derived (b)
|}

A signal is referred to in the literature as an ''event'' or ''hit'', whereby the term hit as defined in DIN EN 1330-9 [2] is used in this procedure. Another variable not shown in the '''Figure''' is the signal energy ''E''AE, which is obtained by integrating the acoustic signal using the equation below. Due to the amplitude-time representation, the unit of energy is abbreviated as ''eu'' for ''energy unit'', which physically corresponds to 1 nVs.
{|
|-
|width="20px"|
|width="500px" | <math>E_{AE}\,=\, \int_{0}^{t_{ED}} U\left( t \right) \, dt</math>
|}

==Signal analysis==

The recorded signals can be analysed in a variety of ways using [[Sound Emission Analysis|sound emission analysis]]. For example, impulse, energy and event measurements can be selected for display in both sum (cumulative) and rate (distributive) modes. In addition, amplitude and [[Frequency Analysis|frequency analysis]] can be performed. The possibilities for evaluating [[Sound Emission|sound emissions]] are shown schematically in '''Fig. 3''' below. The representation of the results in sum and rate form serves to characterise the signal dynamics and thus the load- and deformation-related damage development and accumulation. In contrast, the representation of the amplitude values and the [[Frequency Analysis|frequency analysis]] can be used to draw conclusions about the [[Deformation Mechanisms|damage mechanisms]] and their temporal assignment. However, [3] points out that the representation via amplitude analysis only allows limited conclusions to be drawn about the damage due to the weakening of the mechanical stress waves by the distance travelled in the [[Material & Werkstoff|material]] and thus by the distance between the sound emission source and the sensor. In these cases, the damage mechanisms can only be assigned by means of [[Frequency Analysis|frequency analysis]] [4, 5].

[[File:Sound Emission Testing-3.jpg]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px" |Possible representations of acoustic emission analysis based on [1]
|}

Sound emission testing is applied in two main areas. On the one hand, applications in the technical sense are possible, e.g. in the area of component monitoring of containers or in the monitoring of crack growth (see: [[Crack Propagation|crack propagation]]) on bridges and dams. On the other hand, the area of application in materials science lies in the investigation of [[Deformation Mechanisms|damage mechanisms]] and the correlations to [[Material Parameter|material properties]] that can be derived from them [2, 5].

==See also==

* [[Sound Emission|Sound emission]]
* [[Sound Analysis|Sound analysis]]
* [[Sound Emission Experimental Conditions|Sound emission experimental conditions]]
* [[Ultrasonic Birefringence|Ultrasonic birefringence]]
* [[Ultrasonic Sensors|Ultrasonic sensors]]
* [[Sound Velocity|Sound velocity]]

'''References'''

{|
|-valign="top"
|[1]
|Bardenheier, R.: Schallemissionsuntersuchungen an polymeren Verbundwerkstoffen – Part I: Das Schallemissionsmeßverfahren als quasi-zerstörungsfreie Werkstoffprüfung. Zeitschrift für Werkstofftechnik, 11 (1980) 41–46
|-valign="top"
|[2]
|DIN EN 1330-9 (2009-09): Non-destructive Testing – Terminology– Part 9: Terms used in Acoustic Emission Testing (withdrawn)
|-valign="top"
|[3]
|Ramirez-Jimenez, C. R., Papadakis, N., Reynolds, N., Gan, T. H., Purnell, P., Pharaoh, M.: Identification of Failure Modes in Glass/Polypropylene Composites by Means of the Primary Frequency Content of the Acoustic Emission Event. Compos. Sci. Technol. 64 (2004) 1819–1827 ; https://doi.org/10.1016/j.compscitech.2004.01.008
|-valign="top"
|[4]
|Bohse, J.: Acoustic Emission Characteristics of Micro-Failure Processes in Polymer Blends and Composites. Compos. Sci. Technol. 60 (2000) 1213–1226; https://doi.org/10.1016/S0266-3538(00)00060-9
|-valign="top"
|[5]
|N. N., Kompendium Schallemissionsprüfung – Acoustic Emission Testing (AT) – Grundlagen, Verfahren und praktische Anwendung. DGZfP-Fachausschuss Schallemissionsprüfverfahren
|}

[[Category:Acoustic Test Methods_Ultrasonics]]

Sound Emission Testing - Revision history

Oluschinski at 13:21, 12 December 2025