ASTM E1932-12(2017)
(Guide)Standard Guide for Acoustic Emission Examination of Small Parts
Standard Guide for Acoustic Emission Examination of Small Parts
SIGNIFICANCE AND USE
4.1 The purpose of the AE examination is to analyze how an examination object is withstanding the applied load, or if it is suffering from some latent damage. Consequently the emission activity must be evaluated in relation to the applied load.
4.2 The applied load (on the examination object) may include mechanical forces (tension, compression or torsional), internal pressure and thermal gradients. It may be short to long, random or cyclic. The applied load may be controlled by the examiner or may already exist as part of the process. In either case the applied load is measured along with the AE activity.
4.3 Possible applications include the determination of part integrity, quality control assessment of production processes on a sampled or 100 % inspection basis, in-process examination during a period of applied load of a fabrication process (for example, spot welding, bonding, soldering, pressing, etc.), proof-testing after fabrication, monitoring a “region of interest” (or concern) of a structure (for example, bridge joint or repair, vessel, pipe), and re–examination after intervals of service.
SCOPE
1.1 This guide covers techniques for conducting acoustic emission (AE) examinations of small parts. It is confined to examination objects (or defined regions of larger objects) where there is low AE signal attenuation throughout the examination region. This eliminates the consideration of complex attenuation factor corrections and multiple sensor and array placements based on overcoming signal losses over distances.
1.2 The guide assumes a typical AE examination as one where there is a controlled or measured stress acting upon the part being monitored by AE. Particular emphasis is placed on sensor and system selection, sensor placements, stressing considerations, noise reduction/rejection techniques, spatial filtering, location determination, use of guard sensors, collection of AE data, AE data analysis and report. The purpose of the AE examination is to analyze how an object under evaluation is withstanding the applied load.
1.3 Possible applications of this guide includes materials characterization, quality control of production processes, proof testing after fabrication, evaluating regions of interest of larger structures and retesting after intervals of service. The applied load may include mechanical forces (tension, compression or torsional) internal pressure and thermal gradients.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: E1932 − 12 (Reapproved 2017)
Standard Guide for
Acoustic Emission Examination of Small Parts
This standard is issued under the fixed designation E1932; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This guide covers techniques for conducting acoustic
E650 Guide for Mounting Piezoelectric Acoustic Emission
emission (AE) examinations of small parts. It is confined to
Sensors
examination objects (or defined regions of larger objects)
E750 Practice for Characterizing Acoustic Emission Instru-
where there is low AE signal attenuation throughout the
mentation
examination region. This eliminates the consideration of com-
E976 GuideforDeterminingtheReproducibilityofAcoustic
plex attenuation factor corrections and multiple sensor and
Emission Sensor Response
array placements based on overcoming signal losses over
E1316 Terminology for Nondestructive Examinations
distances.
E2374 Guide for Acoustic Emission System Performance
1.2 The guide assumes a typical AE examination as one
Verification
where there is a controlled or measured stress acting upon the
part being monitored by AE. Particular emphasis is placed on
3. Terminology
sensor and system selection, sensor placements, stressing
3.1 Definitions:
considerations, noise reduction/rejection techniques, spatial
3.1.1 Terminology related to acoustic emission is defined in
filtering, location determination, use of guard sensors, collec-
Terminology E1316.
tion of AE data, AE data analysis and report. The purpose of
3.2 Definitions of Terms Specific to This Standard:
the AE examination is to analyze how an object under
3.2.1 applied load—a controlled or known force or stress
evaluation is withstanding the applied load.
whichisappliedtoanobjectunderexaminationforthepurpose
1.3 Possible applications of this guide includes materials
of analyzing the object’s reaction (by means ofAE monitoring)
characterization, quality control of production processes, proof
to that stress.
testing after fabrication, evaluating regions of interest of larger
3.2.2 guard sensors—sensors whose primary function is the
structures and retesting after intervals of service. The applied
elimination of extraneous noise based on arrival sequences.
load may include mechanical forces (tension, compression or
3.2.3 spatial discrimination—the process of using one or
torsional) internal pressure and thermal gradients.
more (guard and data) sensors to eliminate extraneous noise
1.4 This standard does not purport to address all of the
based on arrival sequences.
safety concerns, if any, associated with its use. It is the
3.2.4 spatial filtering—ability of an AE system or analysis
responsibility of the user of this standard to establish appro-
to disregard AE activity based on source location of the AE
priate safety and health practices and determine the applica-
event.
bility of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
4. Significance and Use
dance with internationally recognized principles on standard-
4.1 The purpose of theAE examination is to analyze how an
ization established in the Decision on Principles for the
examination object is withstanding the applied load, or if it is
Development of International Standards, Guides and Recom-
suffering from some latent damage. Consequently the emission
mendations issued by the World Trade Organization Technical
activity must be evaluated in relation to the applied load.
Barriers to Trade (TBT) Committee.
4.2 The applied load (on the examination object) may
include mechanical forces (tension, compression or torsional),
This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-
tive Testing and is the direct responsibility of Subcommittee E07.04 on Acoustic
Emission Method. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
CurrenteditionapprovedJune1,2017.PublishedJuly2017.Originallyapproved contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
in 1998. Last previous edition approved in 2012 as E1932 - 12. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
E1932-12R17. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1932 − 12 (2017)
internalpressureandthermalgradients.Itmaybeshorttolong, result. In cases where the applied load is part of the process
random or cyclic. The applied load may be controlled by the being monitored, a suitable time forAE monitoring needs to be
examiner or may already exist as part of the process. In either
determined where process noise is low and applied load (for
case the applied load is measured along with the AE activity. AE examination purposes) maximum. Sometimes (if needed)
the applied loading can be altered to achieve this without
4.3 Possible applications include the determination of part
compromising the process (for example, inserting a short load
integrity,qualitycontrolassessmentofproductionprocesseson
hold at maximum load).
a sampled or 100 % inspection basis, in-process examination
(1) In cases where the applied load is controlled with the
during a period of applied load of a fabrication process (for
example, spot welding, bonding, soldering, pressing, etc.), examination, then consideration should be given to design the
loading schedule to appropriately stress the examination object
proof-testing after fabrication, monitoring a “region of inter-
est” (or concern) of a structure (for example, bridge joint or in order to excite “latent flaws” without over-stressing or
repair, vessel, pipe), and re–examination after intervals of damaging the object. In addition, the loading schedule should
service. be designed to provide best insight into the integrity of the part
(for example, implementing a load schedule to evaluate the
5. Procedure
“Kaiser effect”).
5.1 Preliminary Information:
5.1.2.3 Sensor Types—Considerations that should guide the
5.1.1 Before examination, the following information, where
user into proper selection include the sensor’s frequency range,
relevant, should be obtained by the AE examiner:
size (including sensor height, diameter and weight), maximum
5.1.1.1 Type of object to be examined, together with layout
or minimum temperature specification, the sensor’s sensitivity
drawings or sketches.
and frequency response, and acoustic impedance matching of
5.1.1.2 Material specifications (including details of heat
the sensor and part.
treatment where possible).
5.1.2.4 Location of Sensors and Placement Strategy—
5.1.1.3 Proposed or existing applied load specification to-
Considerations need to be given to the number of sensors
gether with a layout or sketch of the pressure/stress application
required for the examination, their placement strategy and
system.
location on the part to be monitored.
5.1.1.4 Information regarding the measuring or recording of
(1) In cases where background noise can be controlled or
theappliedloadmustalsobeobtainedinordertodeterminethe
does not exist, then a single sensor near the expected source of
compatibility with the AE equipment.
the AE is sufficient.
5.1.1.5 Potential sources of background noise and the iso-
(2) In cases where there are a limited number of back-
lating mechanisms applied thereto.
ground noise sources (such as the grips in a tension test), a
5.1.1.6 Previous history, including the maximum applied
single AE data sensor near the expected source of AE and the
load to which the object or system has been subjected.
use of a guard sensor near each background source will
5.1.1.7 Where possible, locations of known discontinuities
effectively block noises that emanate from a region closer to
and the general results of earlier AE or other NDE examina-
the guard sensors than to the AE data sensor. Alternatively, a
tions.
group of two or more sensors can be strategically placed to
5.1.1.8 Results of earlier examinations on similar objects.
perform spatial discrimination of background noise and allow
5.1.2 Before examination, theAE examiner should consider
processing of AE events.
the following information. Some details need to be coordinated
(3) In cases where extraneous noise cannot be controlled
with the on-site management or responsible personnel:
and could be emanating from any or all directions, a multiple-
5.1.2.1 The Type of AE Equipment to be Used—
sensor location strategy (such as linear or planar location)
Considerations should include the number of channels, the
should be considered. In this situation, enough sensors should
frequency range of the instrument’s filters, the real-time data
be specified to allow for an accurate source location, and
processing rates for the type of application, its location/guard/
means should be available to allow for the application of
spatial filtering capabilities, the type of data being collected
spatial filtering and/or spatial discrimination so that only data
(for example, RMS, ASL, AE feature based or waveform
emanating from the region of interest is processed as relevant
based) and the compatibility of the system to monitor and
AE data.
record the applied load during the AE examination. These
5.1.2.5 Data to be Recorded—The AE examiner should
items must be able to perform at the anticipated levels of
know in advance the data and information to be recorded and
performance expected during the examination. In addition,
have all the necessary equipment, hardware, accessories and
consideration should be given to the data analysis, display and
software to acquire, store, and process this information. Other
replay capabilities of the equipment to assure its ability to
process the stored data in a way needed to arrive at a than the equipment forAE monitoring, appropriate sensors and
devices are required for measuring and recording the applied
satisfactory conclusion and examination result.
5.1.2.2 Application of Load—Consideration should be given load and other load or condition related parametric data.
to the application of the load in relation to the integrity of the Details of any interfaces may need to be coordinated with the
examination object and achieving a successfulAE
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1932 − 12 E1932 − 12 (Reapproved 2017)
Standard Guide for
Acoustic Emission Examination of Small Parts
This standard is issued under the fixed designation E1932; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*Scope
1.1 This guide covers techniques for conducting acoustic emission (AE) examinations of small parts. It is confined to
examination objects (or defined regions of larger objects) where there is low AE signal attenuation throughout the examination
region. This eliminates the consideration of complex attenuation factor corrections and multiple sensor and array placements based
on overcoming signal losses over distances.
1.2 The guide assumes a typical AE examination as one where there is a controlled or measured stress acting upon the part being
monitored by AE. Particular emphasis is placed on sensor and system selection, sensor placements, stressing considerations, noise
reduction/rejection techniques, spatial filtering, location determination, use of guard sensors, collection of AE data, AE data
analysis and report. The purpose of the AE examination is to analyze how an object under evaluation is withstanding the applied
load.
1.3 Possible applications of this guide includes materials characterization, quality control of production processes, proof testing
after fabrication, evaluating regions of interest of larger structures and retesting after intervals of service. The applied load may
include mechanical forces (tension, compression or torsional) internal pressure and thermal gradients.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E650 Guide for Mounting Piezoelectric Acoustic Emission Sensors
E750 Practice for Characterizing Acoustic Emission Instrumentation
E976 Guide for Determining the Reproducibility of Acoustic Emission Sensor Response
E1316 Terminology for Nondestructive Examinations
E2374 Guide for Acoustic Emission System Performance Verification
3. Terminology
3.1 Definitions:
3.1.1 Terminology related to acoustic emission is defined in Terminology E1316.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 applied load—a controlled or known force or stress which is applied to an object under examination for the purpose of
analyzing the object’s reaction (by means of AE monitoring) to that stress.
3.2.2 guard sensors—sensors whose primary function is the elimination of extraneous noise based on arrival sequences.
This guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.04 on Acoustic Emission
Method.
Current edition approved June 15, 2012June 1, 2017. Published September 2012July 2017. Originally approved in 1998. Last previous edition approved in 20072012 as
E1932 - 07.E1932 - 12. DOI: 10.1520/E1932-12.10.1520/E1932-12R17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1932 − 12 (2017)
3.2.3 spatial discrimination—the process of using one or more (guard and data) sensors to eliminate extraneous noise based on
arrival sequences.
3.2.4 spatial filtering—ability of an AE system or analysis to disregard AE activity based on source location of the AE event.
4. Significance and Use
4.1 The purpose of the AE examination is to analyze how an examination object is withstanding the applied load, or if it is
suffering from some latent damage. Consequently the emission activity must be evaluated in relation to the applied load.
4.2 The applied load (on the examination object) may include mechanical forces (tension, compression or torsional), internal
pressure and thermal gradients. It may be short to long, random or cyclic. The applied load may be controlled by the examiner
or may already exist as part of the process. In either case the applied load is measured along with the AE activity.
4.3 Possible applications include the determination of part integrity, quality control assessment of production processes on a
sampled or 100 % inspection basis, in-process examination during a period of applied load of a fabrication process (for example,
spot welding, bonding, soldering, pressing, etc.), proof-testing after fabrication, monitoring a “region of interest” (or concern) of
a structure (for example, bridge joint or repair, vessel, pipe), and re–examination after intervals of service.
5. Procedure
5.1 Preliminary Information:
5.1.1 Before examination, the following information, where relevant, should be obtained by the AE examiner:
5.1.1.1 Type of object to be examined, together with layout drawings or sketches.
5.1.1.2 Material specifications (including details of heat treatment where possible).
5.1.1.3 Proposed or existing applied load specification together with a layout or sketch of the pressure/stress application system.
5.1.1.4 Information regarding the measuring or recording of the applied load must also be obtained in order to determine the
compatibility with the AE equipment.
5.1.1.5 Potential sources of background noise and the isolating mechanisms applied thereto.
5.1.1.6 Previous history, including the maximum applied load to which the object or system has been subjected.
5.1.1.7 Where possible, locations of known discontinuities and the general results of earlier AE or other NDE examinations.
5.1.1.8 Results of earlier examinations on similar objects.
5.1.2 Before examination, the AE examiner should consider the following information. Some details need to be coordinated
with the on-site management or responsible personnel:
5.1.2.1 The Type of AE Equipment to be Used—Considerations should include the number of channels, the frequency range of
the instrument’s filters, the real-time data processing rates for the type of application, its location/guard/spatial filtering capabilities,
the type of data being collected (for example, RMS, ASL, AE feature based or waveform based) and the compatibility of the system
to monitor and record the applied load during the AE examination. These items must be able to perform at the anticipated levels
of performance expected during the examination. In addition, consideration should be given to the data analysis, display and replay
capabilities of the equipment to assure its ability to process the stored data in a way needed to arrive at a satisfactory conclusion
and examination result.
5.1.2.2 Application of Load—Consideration should be given to the application of the load in relation to the integrity of the
examination object and achieving a successful AE examination result. In cases where the applied load is part of the process being
monitored, a suitable time for AE monitoring needs to be determined where process noise is low and applied load (for AE
examination purposes) maximum. Sometimes (if needed) the applied loading can be altered to achieve this without compromising
the process (for example, inserting a short load hold at maximum load).
(1) In cases where the applied load is controlled with the examination, then consideration should be given to design the loading
schedule to appropriately stress the examination object in order to excite “latent flaws” without over-stressing or damaging the
object. In addition, the loading schedule should be designed to provide best insight into the integrity of the part (for example,
implementing a load schedule to evaluate the “Kaiser effect”).
5.1.2.3 Sensor Types—Considerations that should guide the user into proper selection include the sensor’s frequency range, size
(including sensor height, diameter and weight), maximum or minimum temperature specification, the sensor’s sensitivity and
frequency response, and acoustic impedance matching of the sensor and part.
5.1.2.4 Location of Sensors and Placement Strategy—Considerations need to be given to the number of sensors required for the
examination, their placement strategy and location on the part to be monitored.
(1) In cases where background noise can be controlled or does not exist, then a single sensor near the expected source of the
AE is sufficient.
(2) In cases where there are a limited number of background noise sources (such as the grips in a tension test), a single AE
data sensor near the expected source of AE and the use of a guard sensor near each background source will effectively block noises
that emanate from a region closer to the guard sensors than to the AE data sensor. Alternatively, a group of two or more sensors
can be strategically placed to perform spatial discrimination of background noise and allow processing of AE events.
(3) In cases where extraneous noise cannot be controlled and could be emanating from any or all directions, a multiple-sensor
location strategy (such as linear or planar location) should be considered. In this situation, enough sensors should be specified to
E1932 − 12 (2017)
allow for an accurate source location, and means should be available to allow for the application of spatial filtering and/or spatial
discrimination so that only data emanating from the region of interest is processed as relevant AE data.
(1) In cases where background noise can be controlled or does not exist, then a single sensor near the expected source of the
AE is sufficient.
(2) In cases where there are a limited number of background noise sources (such as the grips in a tension test), a single AE data
sensor near the expected source of AE and the use of a guard sensor near each background source will effectively block noises
that emanate from a region closer to the guard sensors than to the AE data sensor. Alternatively, a group of two or more sensors
can be strategically placed to perform spatial discrimination of background noise and allow processing of AE events.
(3) In cases where extraneous noise cannot be controlled and could be emanating from any or all directions, a multiple-sensor
location strategy (such as linear or planar location) should be considered. In this situation, enough sensors should be specified to
allow for an accurate source location, and means should be available to allow for the application of spatial filtering and/or spatial
discrimination so that only data emanating from the region of interest is processed as relevant AE data.
5.1.2.5 Data to be Recorded—The AE examiner should know in advance the data and information to be recorded and have all
the necessary equipment, hardware, accessories and software to acquire, store, and process this information. Other than the
equipment for AE monitoring, appropriate sensors and devices are required for measuring and recording the applied load and other
load or condition related parametric data. Details of any interfaces may need to be coordinated with the examination site
management and personnel.
5.1.2.6 Applicability and possible limitations of the method for the particular examination.
5.1.2.7 Any preconditions necessary for conducting the AE examination such as surface preparation or limitation of
pressurization rate needs to be coordinated with the examination-site management or responsible personnel.
5.2 Sensor Installation—The methods and procedures used in mounting AE sensors can have significant effects upon the
performance of those sensors. Optimum and reproducible detection of AE requires both appropriate sensor-mounting fixtures and
consistent sensor-mounting procedures. Refer to Guide E650.
5.3 Calibration and Verification:
5.3.1 Annual calibration and verification of pressure transducer, AE sensors, preamplifiers (if applicable), signal processor
(particularly the signal processor time reference), and AE electronic simulator (waveform generator) should be performed.
Equipment should be adjusted so that it conforms to the equipment manufacturer’s specifications. Instruments used for calibrations
must have current accuracy certification that is traceable to the National Institute for Standards and Technology (NIST).
5.3.2 Routine electronic evaluations should be performed any time there is concern about signal processor performance. An AE
electronic simulator (waveform generator) should be used in making evaluations. Each signal processor channel must respond with
peak amplitude reading within 62 dBV of the electronic waveform generator output. Guide E750 describes other measurements
for characterizing AE equipment.
5.3.3 A system performance verification should be conducted immediately before, and immediately after, each AE examination.
In addition, a system performance verification can be conducted during the examination if there is any suspicion that the system
performance may have changed. A performance check uses a mechanical device to induce stress waves into the examination object
at a specified distance from each sensor (see Guide E2374). Induced stress waves stimulate a sensor in a manner similar to an
acoustic emission. Performance checks verify performance of the entire system (including couplant).
5.3.3.1 The preferred technique for conducting a performance check is a pencil lead break. Lead should be broken on the
examination object surface at a prescribed distance from the sensor (see 4.3.3 in Guide E976). In establishing the details of the
lead break technique, care should be taken to avoid saturating the electronics.
5.4 Examination:
5.4.1 Pre-Examination Requirements—Before the AE examination
...
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