ASTM E2374-16(2021)

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.
Designation: E2374 −16 (Reapproved 2021)
Standard Guide for
Acoustic Emission System Performance Verification
This standard is issued under the fixed designation E2374; 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
1.1 System performance verification methods launch stress 2.1 ASTM Standards:
waves into the examination article on which the sensor is
E750 Practice for Characterizing Acoustic Emission Instru-
mounted. The resulting stress wave travels in the examination mentation
article and is detected by the sensor(s) in a manner similar to
E976 GuideforDeterminingtheReproducibilityofAcoustic
acoustic emission. Emission Sensor Response
E1316 Terminology for Nondestructive Examinations
1.2 This guide describes methods which can be used to
E1419 Practice for Examination of Seamless, Gas-Filled,
verify the response of an Acoustic Emission system including
Pressure Vessels Using Acoustic Emission
sensors, couplant, sensor mounting devices, cables and system
E1781 Practice for Secondary Calibration ofAcoustic Emis-
electronic components.
sion Sensors
1.3 Acoustic emission system performance characteristics,
which may be evaluated using this document, include some
3. Terminology
waveform parameters, and source location accuracy.
3.1 Definitions of Terms Specific to This Standard:
1.4 Performance verification is usually conducted prior to
3.1.1 examination article—the item which is being exam-
beginning the examination.
ined with AE and to which AE sensors are attached.
1.5 Performance verification can be conducted during the
3.1.2 velocity—the measured velocity of a stress wave,
examination if there is any suspicion that the system perfor-
traveling in the examination article, using specifiedAE system
mance may have changed.
parameters and components. Velocity is often used in triangu-
lation calculations to determine the position of the AE source.
1.6 Performance verification may be conducted after the
examination has been completed.
3.1.3 auto sensor test (AST)—an electronic means by which
a sensor can be fed an electronic pulse to excite the examina-
1.7 The values stated in SI units are to be regarded as
tionarticle.Theresultingstresswaveintheexaminationarticle
standard. No other units of measurement are included in this
canbemeasuredbythesamesensororbyothersensorsthatare
standard.
on the same examination article. See 3.1.4 and 3.1.5.
1.8 This standard does not purport to address all of the
3.1.4 auto sensor test-self test mode—a means by which an
safety concerns, if any, associated with its use. It is the
AST sensor may be used to check its own performance.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3.1.5 auto sensor test-near neighbor mode—a means by
mine the applicability of regulatory limitations prior to use.
which anAST sensor may be used to determine the sensitivity
1.9 This international standard was developed in accor-
of one or more neighboring sensors on the same examination
dance with internationally recognized principles on standard-
article.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Significance and Use
mendations issued by the World Trade Organization Technical
4.1 Acoustic Emission data acquisition can be affected by
Barriers to Trade (TBT) Committee.
numerous factors associated with the electronic
instrumentation, cables, sensors, sensor holders, couplant, the
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
Current edition approved Nov. 1, 2021. Published November 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2004. Last previous edition approved in 2016 as E2374 - 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2374-16R21. 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
E2374 − 16 (2021)
examination article on which the sensor is mounted, back- conjunction with an electronic signal or pulse generator. The
ground noise, and the user’s settings of the acquisition param- electrical signal from the signal/pulse generator is converted
eters (for example, threshold). into a mechanical displacement by the transducer’s crystal.
(See Guide E976, subsection 4.3.1.) One significant advantage
4.2 This guide is not intended to replace annual (or semi-
ofthistechniqueisthattheoutputoftheelectronicsignal/pulse
annual) instrumentation calibration (see Practice E750)or
generator can be adjusted in numerous ways (for example,
sensor recertification (see Practice E1781).
amplitude and repetition rate).
4.3 This guide is not intended to replace routine electronic
5.1.2.1 The independent pulser can be used to excite the
evaluation of AE instrumentation or routine reproducibility
receivingAE sensor before, during and after an examination as
verification of AE sensors (see Guide E976).
verification that there were no changes in coupling or sensor
4.4 This guide is not intended to verify the maximum
response. The independent pulser technique is particularly
processing capacity or speed of an AE system.
useful when there is limited access to the examination article
thatwouldprecludetheuseofmanualtechniques(forexample,
4.5 This guide does not purport to address all of the safety
PLB).
concerns, if any associated with its use. It is the responsibility
of the user of this guide to establish appropriate safety and
5.1.2.2 The independent pulser technique is particularly
health practices and determine the applicability of regulatory
useful in continuous monitoring situations where sensors will
limitations prior to use.
be on the examination article for a long period of time. In this
situation the independent pulser is left in place and used
5. Apparatus
periodically to assure system performance.
5.1.3 AST Capable Integrated Pulser/Sensor—An AE sen-
5.1 To determine system performance a sensor must be
sor that has been designed to accept an electronic signal/pulse
subjected to a stress wave traveling in the examination article.
into its crystal. The mechanical displacement of the crystal
Transient stress waves are launched by mechanical or electro-
excites the examination article. The stress wave generated in
mechanical devices that produce a waveform with fast rise-
the examination article can be detected by other sensors on the
time, short duration and repeatable peak amplitude. Steady
same examination article. With certain realizations of theAST
state (continuous) stress waves are launched by mechanical or
electromechanical devices that produce a waveform with long function (self test mode), it can also be detected by the exciting
sensor.
duration constant amplitude. Various apparatus can be used as
verification sources including the following:
5.1.3.1 Auto Sensor Test: Near Neighbor Mode—An inte-
5.1.1 Pencil Lead Break (PLB)—A mechanical pencil tech-
grated pulser/sensor can be used to measure sensitivity and
nique whereby lead is pushed against the examination article’s
time-of-flight (that is, the time required for a stress wave to
surface with sufficient force to break the lead. When the lead
travel the sensor-spacing distance) for neighboring sensors on
breaks, there is a sudden release of stress on the surface. (See
the same examination article. The time-of-flight can be used to
Guide E976, subsection 4.3.3 and Fig. 5.)
calculate the apparent velocity of the stress wave (apparent
5.1.1.1 The distance between the PLB and the sensor must
velocity = sensor spacing/time-of-flight).
be specified and kept consistent.
5.1.3.2 Auto Sensor Test: Self Test Mode—An integrated
5.1.1.2 The “Hsu pencil source” uses a mechanical pencil
pulser/sensor can be used to verify the performance of the
with a 2.5 mm lead extension, 2H hardness and 0.3 mm or 0.5
sensor coupling and the sensor and channel electronics to
mm diameter (0.3 mm is preferred).
which it is attached by establishing a baseline duration (or
5.1.1.3 The “Nielsen shoe” can aid in breaking the lead
energy) measured from the AST pulse using a sensor that is
consistently.
known to be operating properly and mounted optimally on the
5.1.1.4 The pencil should be held at an angle of 30 degrees
examination article. The baseline duration number (for
to the surface.
example, 10 000 µs) can then be compared with the AST
5.1.1.5 Three to five lead breaks are generally conducted to
duration measurements from each channel on the examination
show a consistent result.
article. Channels, which produce AST duration measurements
5.1.1.6 Application standards (for example, Test Method
that are low compared to the baseline, should be recoupled,
E1419,Table X1.2) specify the minimum signal amplitude that
repaired or replaced as necessary.
must be measured by the AE instrumentation.
5.1.4 Spring Loaded Center Punch—Aspring loaded device
5.1.1.7 Channels which are found to have unacceptably low
that imparts a mechanical impact force, creating a very large
or high sensitivity can be re-coupled (that is, replace couplant),
stress wave on the examination article. The spring assures a
repaired (that is, replace sensor, or cable, or both), or replaced
consistent and repeatable force.
to the examination article (that is, exchanged for another
5.1.4.1 The spring-loaded center punch is of particular
channel), or both.
advantagewhenAEsensorsaredistributedoverlargedistances
5.1.1.8 PLB can be used to determine the apparent velocity
on an examination article, as the imparted force is so strong it
in the examination article (apparent velocity = sensor spacing/
can be detected easily.
time-of-flight).“Time-of-flight”isthetimerequiredforastress
wave to travel the sensor-spacing distance 5.1.4.2 The spring-loaded center punch is readily available
5.1.2 Independent Piezoelectric Pulser—An electrome- and easy to apply anywhere on the examination article, at any
chanicaldeviceheldagainsttheexaminationarticleandusedin time.
E2374 − 16 (2021)
5.1.4.3 To avoid damage to the surface, it is desirable to 6. Procedure
apply the center punch through an intermediate interface such
6.1 The procedure for accomplishing system performance
as a thin sheet of metal.
verification utilizes one of the devices listed in Section 5 to
5.1.5 Projectile—An object which is launched or projected
produce a stress wave on the examination article. The
to impact the surface of the examination article.
...