ASTM E750-15(2020)
(Practice)Standard Practice for Characterizing Acoustic Emission Instrumentation
Standard Practice for Characterizing Acoustic Emission Instrumentation
ABSTRACT
This practice deals with the testing and measurement of operating characteristics of acoustic emission (AE) electronic components or units. This practice is not intended for routine checks of acoustic emission instrumentation, but rather for periodic evaluation or in the event of a malfunction. The sensor is not addressed in this document other than suggesting methods for standardizing system gains (equalizing them channel to channel) when sensors are present. The test methods and measurement techniques used and their corresponding results should be recorded in documentation, which consists of photographs, charts or graphs, calculations, and tabulations where applicable. This practice does not cover the testing of the computer or computer peripherals used in conjunction with AE systems that use them to control the collection, storage, display, and analysis of data. Instead a manufacturer's specification should be provided for such purpose.
SIGNIFICANCE AND USE
5.1 This practice provides information necessary to document the accuracy and performance of an Acoustic Emission system. This information is useful for reference purposes to assure that the instrumentation performance remains consistent with time and use, and provides the information needed to adjust the system to maintain its consistency.
5.2 The methods set forth in this practice are not intended to be either exclusive or exhaustive.
5.3 Difficult or questionable instrumentation measurements should be referred to electronics engineering personnel.
5.4 It is recommended that personnel responsible for carrying out instrument measurements using this practice should be experienced in instrumentation measurements, as well as all the required test equipment being used to make the measurements.
SCOPE
1.1 This practice is recommended for use in testing and measuring operating characteristics of acoustic emission electronic components or units. (See Appendix X1 for a description of components and units.) It is not intended that this practice be used for routine checks of acoustic emission instrumentation, but rather for periodic evaluation or in the event of a malfunction. The sensor is not addressed in this document other than suggesting methods for standardizing system gains (equalizing them channel to channel) when sensors are present.
1.2 Where the manufacturer provides testing and measuring details in an operating and maintenance manual, the manufacturer's methods should be used in conjunction with the methods described in this practice.
1.3 The methods (techniques) used for testing and measuring the components or units of acoustic emission instrumentation, and the results of such testing and measuring should be documented. Documentation should consist of photographs, screenshots, charts or graphs, calculations, and tabulations where applicable.
1.4 AE systems that use computers to control the collection, storage, display, and data analysis, might include waveform collection as well as a wide selection of measurement parameters (features) relating to the AE signal. The manufacturer provides a specification for each system that specifies the operating range and conditions for the system. All calibration and acceptance testing of computer-based AE systems must use the manufacturer's specification as a guide. This practice does not cover testing of the computer or computer peripherals.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardiz...
General Information
Relations
Standards Content (Sample)
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:E750 −15 (Reapproved 2020)
Standard Practice for
Characterizing Acoustic Emission Instrumentation
This standard is issued under the fixed designation E750; 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* priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This practice is recommended for use in testing and
1.7 This international standard was developed in accor-
measuring operating characteristics of acoustic emission elec-
dance with internationally recognized principles on standard-
troniccomponentsorunits.(SeeAppendixX1foradescription
ization established in the Decision on Principles for the
ofcomponentsandunits.)Itisnotintendedthatthispracticebe
Development of International Standards, Guides and Recom-
used for routine checks of acoustic emission instrumentation,
mendations issued by the World Trade Organization Technical
but rather for periodic evaluation or in the event of a malfunc-
Barriers to Trade (TBT) Committee.
tion. The sensor is not addressed in this document other than
suggesting methods for standardizing system gains (equalizing
2. Referenced Documents
them channel to channel) when sensors are present.
2.1 ASTM Standards:
1.2 Where the manufacturer provides testing and measuring
E1316 Terminology for Nondestructive Examinations
details in an operating and maintenance manual, the manufac-
turer’s methods should be used in conjunction with the 2.2 ANSI Standard:
methods described in this practice. ANSI/IEEE 100-1984 Dictionary of Electrical and Elec-
tronic Terms
1.3 The methods (techniques) used for testing and measur-
ing the components or units of acoustic emission 2.3 Other Documents:
Manufacturer’s Operating and Maintenance Manuals perti-
instrumentation, and the results of such testing and measuring
should be documented. Documentation should consist of nent to the specific instrumentation or component
photographs, screenshots, charts or graphs, calculations, and
tabulations where applicable. 3. Terminology
3.1 Definitions—For definitions of additional terms relating
1.4 AE systems that use computers to control the collection,
storage, display, and data analysis, might include waveform to acoustic emission, refer to Terminology E1316.
collection as well as a wide selection of measurement param-
eters (features) relating to the AE signal. The manufacturer 4. Summary of Practice
provides a specification for each system that specifies the
4.1 Tests and measurements should be performed to deter-
operating range and conditions for the system. All calibration
mine the instrumentation bandwidth, frequency response, gain,
andacceptancetestingofcomputer-basedAEsystemsmustuse
noise level, threshold level, dynamic range, signal overload
the manufacturer’s specification as a guide. This practice does
point, dead time, and counter accuracy.
not cover testing of the computer or computer peripherals.
4.2 Where acoustic emission test results depend upon the
1.5 The values stated in SI units are to be regarded as
reproduced accuracy of the temporal, spatial, or spectral
standard. No other units of measurement are included in this
histories, additional measurements of instrumentation param-
standard.
eters should be performed to determine the specific limits of
1.6 This standard does not purport to address all of the
instrumentation performance. Examples of such measurements
safety concerns, if any, associated with its use. It is the
may include amplifier slew rate, gate window width and
responsibility of the user of this standard to establish appro-
position, and spectral analysis.
1 2
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
structive Testing and is the direct responsibility of Subcommittee E07.04 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Acoustic Emission Method. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJune1,2020.PublishedJuly2020.Originallyapproved the ASTM website.
in 1980. Last previous edition approved in 2015 as E750 – 15. DOI: 10.1520/ Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
E0750-15R20. 4th Floor, New York, NY 10036.
*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
E750−15 (2020)
4.3 Tests and measurements should be performed to deter- 6. Apparatus
mine the loss in effective sensor sensitivity resulting from the
6.1 The basic test instruments required for measuring the
capacitive loading of the cable between the preamplifier and
operating characteristics of acoustic emission instrumentation
the sensor. The cable and preamplifier should be the same as
include:
that used for the acoustic emission tests without substitution.
6.1.1 Variable Sine Wave Generator or Oscillator,
(See also Appendix Appendix X2.)
6.1.2 True RMS Voltmeter,
4.3.1 Important tests of a computer-based AE system in-
6.1.3 Oscilloscope,
clude the evaluation of limits and linearity of the available
6.1.4 Variable Attenuator, graduated in decibels, and
parameters such as:
6.1.5 Tone Burst Generator.
(a) Amplitude,
6.2 Additional test instruments may be used for more
(b) Duration,
specialized measurements of acoustic emission instrumenta-
(c) Rise Time,
tions or components. They are as follows:
(d) Energy, and
6.2.1 Variable-Function Generator,
(e) AE Arrival Time.
6.2.2 Time Interval Meter,
4.3.2 The processing speed of these data should be mea-
6.2.3 Frequency Meter, or Counter,
sured as described in 7.4.3 for both single- and multiple-
6.2.4 Random Noise Generator,
channel operation.
6.2.5 Spectrum Analyzer,
4.3.3 The data storage capability should be tested against
6.2.6 D-C Voltmeter,
the specification for single- and multiple-channel operation.
6.2.7 Pulse-Modulated Signal Generator,
Processing speed is a function of number of channels, param-
6.2.8 Variable Pulse Generator,
eters being measured, timing parameter settings, AE signal
6.2.9 Phase Meter, and
duration, front-end filtering, storage device (RAM, disk), and
6.2.10 Electronic AE Simulator (or an Arbitrary Waveform
on-line analysis settings (number of graphs, data listings,
Generator (AWG) can be used providing an automated evalu-
location algorithms, and more). If waveform recording is used,
ation).
this may influence the processing speed further.
6.3 An electronic AE simulator (or AWG) is necessary to
5. Significance and Use
evaluate the operation of computer-based AE instruments. A
5.1 This practice provides information necessary to docu- detailed example of the use of an electronic AE simulator (or
ment the accuracy and performance of an Acoustic Emission AWG) is given in 7.4.3 under dead time measurement. The
system. This information is useful for reference purposes to instruction manual for the electronic AE simulator provides
assure that the instrumentation performance remains consistent details on the setup and adjustment of the simulator. Control of
with time and use, and provides the information needed to pulse frequency, rise time, decay, repetition rate, and peak
adjust the system to maintain its consistency. amplitude in the simulator makes it possible to simulate a wide
range of AE signal conditions.
5.2 Themethodssetforthinthispracticearenotintendedto
be either exclusive or exhaustive.
7. Measurement Procedure
5.3 Difficult or questionable instrumentation measurements
7.1 Frequency Response and Bandwidth Measurements:
should be referred to electronics engineering personnel.
7.1.1 The instrumentation, shown in Fig. 1, includes the
5.4 It is recommended that personnel responsible for carry- preamplifier with amplification and signal filters, possibly
ing out instrument measurements using this practice should be connectedtotheAEsystemwhichmighthaveadditionalsignal
experienced in instrumentation measurements, as well as all filters, amplification, and interconnecting cables. All measure-
the required test equipment being used to make the measure- ments and tests should be documented. If the preamplifier is to
ments. be tested without the AE system connected, it should be
FIG. 1 Component Configuration Used for Testing and Measuring the Frequency Response, Amplification, Noise, Signal Overload, Re-
covery Time, and Threshold of Acoustic Emission Instrumentation
E750−15 (2020)
terminated with the normal working load as shown on the white noise generator or sweep generator and spectrum or FFT
bottom right of Fig. 1. analyzer may be used in place of the oscillator and RMS
7.1.2 An acceptable frequency response should be flat voltmeter.
between cutoff frequencies within 3 dB of the reference
NOTE 1—If the input impedance of the preamplifier is not both resistive
frequency. The reference frequency is the geometric mean of
and equal to the required load impedance of the attenuator, proper
the nominal bandwidth of the instrumentation. The mean
compensation should be made.
frequency is calculated as follows:
7.3 Dynamic Range Measurements:
f 5 f f 2 7.3.1 The criterion used for establishing dynamic range
~ !
M L H
should be documented as the signal overload point, referenced
where:
to the instrumentation noise amplitude, while keeping like
f = mean frequency,
M
measurements for both readings (for example, peak voltage to
f = nominal lower cutoff, and
L
peak voltage, peak-peak voltage or RMS to RMS readings).
f = nominal upper cutoff.
H
Alternatively, the reference amplitude may be the threshold
7.1.3 The bandwidth should include all contiguous frequen-
level if the instrumentation includes a voltage comparator for
cieswithamplitudevariationsasspecifiedbythemanufacturer.
signal detection. The total harmonic distortion criterion should
Instruments that include signal processing of amplitude as a
be used for signal processing involving spectrum analysis. All
function of frequency should have bandwidth amplitude varia-
other signal processing may be performed with the signal
tions as specified by the manufacturer. overload point criterion.
7.1.4 With the instrumentation connected to the oscillator
7.3.2 The dynamic range (DR) in decibels should be deter-
and attenuator, see Fig. 1 and the sine wave oscillator set well
mined as follows:
within the instrumentation’s specified dynamic range, the
DR 5 20 log signal overload point voltage/background noise voltage
~ !
frequency response should be measured between frequency
limits specified in 7.1.2. The oscillator is maintained at a fixed 7.3.2.1 The dynamic range of instrumentation exclusive of
amplitude and the frequency is swept through the frequency threshold or voltage comparator circuits, is a ratio of the signal
limits. The preamplifier or AE system voltage output is overload level to the noise amplitude. (A brief description of
monitored with an RMS voltmeter. Values of amplitude are noise sources appears in Appendix X4). An oscilloscope is
recorded for each of several frequencies within and beyond the usually required as an adjunct to determine the characteristics
nominal cutoff frequencies. The recorded values should be of noise and to monitor the signal overload point.
plotted.The amplitude scale may be converted to decibels.The
7.3.2.2 Afield measurement of dynamic range may produce
frequency scale may be plotted either linearly or logarithmi-
substantially different results when compared with a laboratory
cally. Appendix X2 provides further discussion of wave
measurement. This difference is caused by an increase in the
shaping components.
reference voltage output, and may result from noise impulses
7.1.5 Aspectrum analyzer may be used in conjunction with of electrical origin, or ground faults.
a white noise source or an oscilloscope may be used in
7.3.2.3 For an amplifier that has a threshold comparator as
conjunction with a sweep frequency oscillator to determine
its output device, the dynamic range is the ratio of maximum
bandwidth. With a white noise source connected to the input, a
threshold level to input noise level at the comparator. Excess
spectrum analyzer connected to the output will record the
amplitude range in the amplifier contributes to overload
frequency response.
immunity but not to the dynamic range. The following mea-
7.1.6 The measured bandwidth is the difference between the
surement will give the effective dynamic range:
corner frequencies at which the response is 3 dB less than the
DR 5 20log MaxTh/MinTh
~ !
e 10
response at the reference frequency.
where:
7.2 Gain Measurements:
DR = the effective dynamic range of the system,
e
7.2.1 The electronic amplification is comprised of the pre-
MaxTh = the highest settable threshold value that just
amplifier gain, the wave filters insertion gains or losses and the
passes the largest undistorted peak signal input,
AE system’s gains or losses. (See Appendix X2 for an
and
explanation of gain measurements.)
MinTh = the threshold value that passes less than 1 count/s
7.2.2 The electronic amplification may be measured with
with no input signal.
thetestsetupshowninFig.1,withtheoscillatorandattenuator
This dynamic range is the difference between the largest and
connected. The sine wave oscillator is set to the reference
the smallest AE input that can be reliably detected by the
frequency. The oscillator amplitude is set well within the
system.
dynamicrangeoftheinstrumentationtoavoiddistortiondueto
overload. With the voltmeter at V , oscillator amplitude is set 7.3.3 Measurement of instrument electronic noise is accom-
osc
to 1 V. The attenuator is set for a value greater than the plished by replacing the oscillator/attenuator of Fig. 1, with the
anticipated electronic amplification. Next, the voltmeter is sensor that will be used, including its cable (or with a lumped
moved to V (preamplifier or AE system voltage output equivalent capacitance). A lumped capacitance represents the
out
depending on the test being performed). The attenuator is now electrical characteristic of the sensor and cable combination
adjusted until the voltmeter again reads 1 V. The electronic without adding mechanical noise interference. The RMS noise
amplification is equal to
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.