Standard Practice for Secondary Calibration of Acoustic Emission Sensors

SIGNIFICANCE AND USE
4.1 The purpose of this practice is to enable the transfer of calibration from sensors that have been calibrated by primary calibration to other sensors.
SCOPE
1.1 This practice covers requirements for the secondary calibration of acoustic emission (AE) sensors. The secondary calibration yields the frequency response of a sensor to waves of the type normally encountered in acoustic emission work. The source producing the signal used for the calibration is mounted on the same surface of the test block as the sensor under testing (SUT). Rayleigh waves are dominant under these conditions; the calibration results represent primarily the sensor's sensitivity to Rayleigh waves. The sensitivity of the sensor is determined for excitation within the range of 100 kHz to 1 MHz. Sensitivity values are usually determined at frequencies approximately 10 kHz apart. The units of the calibration are volts per unit of mechanical input (displacement, velocity, or acceleration).  
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standards.  
1.3 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.

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Publication Date
31-May-2013
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Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1781/E1781M − 13
Standard Practice for
1
Secondary Calibration of Acoustic Emission Sensors
ThisstandardisissuedunderthefixeddesignationE1781/E1781M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* E1106Test Method for Primary Calibration of Acoustic
Emission Sensors
1.1 This practice covers requirements for the secondary
E1316Terminology for Nondestructive Examinations
calibration of acoustic emission (AE) sensors. The secondary
calibration yields the frequency response of a sensor to waves
3. Terminology
of the type normally encountered in acoustic emission work.
3.1 Definitions—Refer to Terminology E1316, Section B,
The source producing the signal used for the calibration is
for terms used in this practice.
mounted on the same surface of the test block as the sensor
3.2 Definitions of Terms Specific to This Standard:
undertesting(SUT).Rayleighwavesaredominantunderthese
3.2.1 reference sensor (RS)—a sensor that has had its
conditions; the calibration results represent primarily the sen-
response established by primary calibration (also called sec-
sor’s sensitivity to Rayleigh waves. The sensitivity of the
ondary standard transducer) (see Method E1106).
sensorisdeterminedforexcitationwithintherangeof100kHz
to1MHz.Sensitivityvaluesareusuallydeterminedatfrequen-
3.2.2 secondary calibration—a procedure for measuring the
cies approximately 10 kHz apart. The units of the calibration frequencyortransientresponseofanAEsensorbycomparison
are volts per unit of mechanical input (displacement, velocity,
with an RS.
or acceleration).
3.2.3 test block—a block of homogeneous, isotropic, elastic
1.2 Units—The values stated in either SI units or inch- material on which a source, an RS, and a SUT are placed for
conducting secondary calibration.
poundunitsaretoberegardedasstandard.Thevaluesstatedin
each system may not be exact equivalents; therefore, each
4. Significance and Use
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance
4.1 The purpose of this practice is to enable the transfer of
with the standards.
calibration from sensors that have been calibrated by primary
calibration to other sensors.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. General Requirements
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5.1 Units for Calibration—Secondary calibration produces
bility of regulatory limitations prior to use. the same type of information regarding a sensor as does
primarycalibration(MethodE1106).AnAEsensorrespondsto
2. Referenced Documents
motion at its front face.The actual stress and strain at the front
2
face of a mounted sensor depends on the interaction between
2.1 ASTM Standards:
the mechanical impedance of the sensor (load) and that of the
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam
mounting block (driver); neither the stress nor the strain is
Contact Testing
amenable to direct measurement at this location. However, the
E494Practice for Measuring Ultrasonic Velocity in Materi-
free displacement that would occur at the surface of the block
als
intheabsenceofthesensorcanbeinferredfrommeasurements
made elsewhere on the surface. Since AE sensors are used to
monitor motion at a free surface of a structure and interactive
1
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
effectsbetweenthesensorandthestructurearegenerallyofno
structive Testing and is the direct responsibility of Subcommittee E07.04 on
Acoustic Emission Method.
interest, the free motion is the appropriate input variable. It is
Current edition approved June 1, 2013. Published June 2013. Originally
thereforerequiredthattheunitsofcalibrationshallbevoltsper
approved in 1996. Last previous edition approved in 2008 as E1781-08. DOI:
unit of free displacement or free velocity, that is, volts per unit
10.1520/E1781_E1781M-13.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or or volt seconds per unit.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.2 The calibration results may be expressed, in the fre-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. quency domain, as the steady-state magnitude and phase
*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
1

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...

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: E1781 − 08 E1781/E1781M − 13
Standard Practice for
1
Secondary Calibration of Acoustic Emission Sensors
This standard is issued under the fixed designation E1781;E1781/E1781M; 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 practice covers requirements for the secondary calibration of acoustic emission (AE) sensors. The secondary
calibration yields the frequency response of a sensor to waves of the type normally encountered in acoustic emission work. The
source producing the signal used for the calibration is mounted on the same surface of the test block as the sensor under testing
(SUT). Rayleigh waves are dominant under these conditions; the calibration results represent primarily the sensor’s sensitivity to
Rayleigh waves. The sensitivity of the sensor is determined for excitation within the range of 100 kHz to 1 MHz. Sensitivity values
are usually determined at frequencies approximately 10 kHz apart. The units of the calibration are volts per unit of mechanical
input (displacement, velocity, or acceleration).
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded as the standard. The values given in
parentheses are for information only. stated in each system may not be exact equivalents; therefore, each system shall be used
independently of the other. Combining values from the two systems may result in non-conformance with the standards.
1.3 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.
2. Referenced Documents
2
2.1 ASTM Standards:
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
E494 Practice for Measuring Ultrasonic Velocity in Materials
E1106 Test Method for Primary Calibration of Acoustic Emission Sensors
E1316 Terminology for Nondestructive Examinations
3. Terminology
3.1 Definitions—Refer to Terminology E1316, Section B, for terms used in this practice.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 reference sensor (RS)—a sensor that has had its response established by primary calibration (also called secondary
standard transducer) (see Method E1106).
3.2.2 secondary calibration—a procedure for measuring the frequency or transient response of an AE sensor by comparison
with an RS.
3.2.3 test block—a block of homogeneous, isotropic, elastic material on which a source, an RS, and a SUT are placed for
conducting secondary calibration.
4. Significance and Use
4.1 The purpose of this practice is to enable the transfer of calibration from sensors that have been calibrated by primary
calibration to other sensors.
1
This practice 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 Dec. 15, 2008June 1, 2013. Published January 2009June 2013. Originally approved in 1996. Last previous edition approved in 19982008 as
ε1
E1781 - 98E1781 - 08.(2003) . DOI: 10.1520/E1781-08.10.1520/E1781_E1781M-13.
2
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
1

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E1781/E1781M − 13
FIG. 1 Schematic of the Prototype Secondary Calibration Apparatus: A = a Capillary-Break Source, B = a 41 by 41 by 19-cm [16 by 16
by 7.5 in.] Steel Block, C = the RS, D = the SUT, and E = the Two-Channel Waveform Recorder System
5. General Requirements
5.1 Units for Calibration—Secondary calibration produces the same type of information regarding a sensor as does primary
calibration (Method E1106). An AE sensor responds to motion at its front face. The actual stress and strain at the front face of a
mounted sensor depends on the interaction between the mechanical impedance of the s
...

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