ASTM E467-08(2014)
(Practice)Standard Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
Standard Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
SIGNIFICANCE AND USE
4.1 It is well understood how to measure the forces applied to a specimen under static conditions. Practices E4 details the required process for verifying the static force measurement capabilities of testing machines. During dynamic operation however, additional errors may manifest themselves in a testing machine. Further verification is necessary to confirm the dynamic force measurement capabilities of testing machines.
Note 1: The static machine verification accomplished by Practices E4 simply establishes the reference. Indicated forces measured from the force cell are compared with the dynamometer conditioned forces statically for confirmation and then dynamically for dynamic verification of the fatigue testing system's force output.
Note 2: The dynamic accuracy of the force cell's output will not always meet the accuracy requirement of this standard without correction. Dynamic correction to the force cell output can be applied provided that verification is performed after the correction has been applied.
Note 3: Overall test accuracy is a combination of measurement accuracy and control accuracy. This practice provides methods to evaluate either or both. As control accuracy is dependent on many more variables than measurement accuracy it is imperative that the test operator utilize appropriate measurement tools to confirm that the testing machine’s control behavior is consistent between verification activities and actual testing activities.
4.2 Dynamic errors are primarily span dependent, not level dependent. That is, the error for a particular force endlevel during dynamic operation is dependent on the immediately preceding force endlevel. Larger spans imply larger absolute errors for the same force endlevel.
4.3 Due to the many test machine factors that influence dynamic force accuracy, verification is recommended for every new combination of potential error producing factors. Primary factors are specimen design, machine configuration, test frequenc...
SCOPE
1.1 This practice covers procedures for the dynamic verification of cyclic force amplitude control or measurement accuracy during constant amplitude testing in an axial fatigue testing system. It is based on the premise that force verification can be done with the use of a strain gaged elastic element. Use of this practice gives assurance that the accuracies of forces applied by the machine or dynamic force readings from the test machine, at the time of the test, after any user applied correction factors, fall within the limits recommended in Section 9. It does not address static accuracy which must first be addressed using Practices E4 or equivalent.
1.2 Verification is specific to a particular test machine configuration and specimen. This standard is recommended to be used for each configuration of testing machine and specimen. Where dynamic correction factors are to be applied to test machine force readings in order to meet the accuracy recommended in Section 9, the verification is also specific to the correction process used. Finally, if the correction process is triggered or performed by a person, or both, then the verification is specific to that individual as well.
1.3 It is recognized that performance of a full verification for each configuration of testing machine and specimen configuration could be prohibitively time consuming and/or expensive. Annex A1 provides methods for estimating the dynamic accuracy impact of test machine and specimen configuration changes that may occur between full verifications. Where test machine dynamic accuracy is influenced by a person, estimating the dynamic accuracy impact of all individuals involved in the correction process is recommended. This practice does not specify how that assessment will be done due to the strong dependence on owner/operators of the test machine.
1.4 This practice is intended to be used periodically. Consistent results between verifications is e...
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Designation:E467 −08 (Reapproved 2014)
Standard Practice for
Verification of Constant Amplitude Dynamic Forces in an
Axial Fatigue Testing System
This standard is issued under the fixed designation E467; 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 obtain consistent results between verifications using the same
machine configuration implies uncertain accuracy for dynamic
1.1 This practice covers procedures for the dynamic verifi-
tests performed during that time period.
cation of cyclic force amplitude control or measurement
accuracy during constant amplitude testing in an axial fatigue 1.5 This practice addresses the accuracy of the testing
testing system. It is based on the premise that force verification machine’s force control or indicated forces, or both, as
can be done with the use of a strain gaged elastic element. Use compared to a dynamometer’s indicated dynamic forces. Force
of this practice gives assurance that the accuracies of forces controlverificationisonlyapplicablefortestsystemsthathave
appliedbythemachineordynamicforcereadingsfromthetest some form of indicated force peak/valley monitoring or am-
machine, at the time of the test, after any user applied plitude control. For the purposes of this verification, the
correction factors, fall within the limits recommended in dynamometer’s indicated dynamic forces will be considered
Section 9. It does not address static accuracy which must first the true forces. Phase lag between dynamometer and force
be addressed using Practices E4 or equivalent. transducer indicated forces is not within the scope of this
practice.
1.2 Verification is specific to a particular test machine
configuration and specimen. This standard is recommended to 1.6 TheresultsofeithertheAnnexA1calculationorthefull
be used for each configuration of testing machine and speci- experimental verification must be reported per Section 10 of
men.Wheredynamiccorrectionfactorsaretobeappliedtotest this standard.
machine force readings in order to meet the accuracy recom-
1.7 This practice provides no assurance that the shape of the
mended in Section 9, the verification is also specific to the
actual waveform conforms to the intended waveform within
correction process used. Finally, if the correction process is
any specified tolerance.
triggered or performed by a person, or both, then the verifica-
1.8 Thisstandardisprincipallyfocusedatroomtemperature
tion is specific to that individual as well.
operation. It is believed there are additional issues that must be
1.3 It is recognized that performance of a full verification
addressed when testing at high temperatures. At the present
for each configuration of testing machine and specimen con-
time, this standard practice must be viewed as only a partial
figuration could be prohibitively time consuming and/or ex-
solution for high temperature testing.
pensive. Annex A1 provides methods for estimating the dy-
1.9 The values stated in inch-pound units are to be regarded
namic accuracy impact of test machine and specimen
as standard. No other units of measurement are included in this
configuration changes that may occur between full verifica-
standard.
tions.Where test machine dynamic accuracy is influenced by a
person, estimating the dynamic accuracy impact of all indi-
1.10 This standard does not purport to address all of the
viduals involved in the correction process is recommended. safety concerns, if any, associated with its use. It is the
This practice does not specify how that assessment will be
responsibility of the user of this standard to establish appro-
done due to the strong dependence on owner/operators of the priate safety and health practices and determine the applica-
test machine.
bility of regulatory limitations prior to use.
1.4 This practice is intended to be used periodically. Con-
2. Referenced Documents
sistent results between verifications is expected. Failure to
2.1 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
This practice is under the jurisdiction ofASTM Committee E08 on Fatigue and
Fractureand is the direct responsibility of Subcommittee E08.03 on Advanced
Apparatus and Techniques. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2014. Published September 2014. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ε1
approved in 1972. Last previous edition approved in 2008 as E467–08 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0467-08R14. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E467−08 (2014)
E6 Terminology Relating to Methods of Mechanical Testing quency and force range. (Refer to Practice E467, AnnexA2 for
E1823 TerminologyRelatingtoFatigueandFractureTesting detailed information about the dynamometer and instrumenta-
E1942 Guide for Evaluating DataAcquisition Systems Used tion.)
in Cyclic Fatigue and Fracture Mechanics Testing
3.2.11 dynamometer force, n—the force value provided by
2.2 Military Standard:
the dynamometer’s readout.
1312-B Fastener Test Methods
3.2.12 endlevel, n—eitheramaximumorminimumlevelfor
2.3 ANSI Standard:
a cyclic waveform.
Z540-1-1994 Calibration Laboratories and Measuring and
3.2.13 fatigue testing system, n—for the purpose of this
Test Equipment—General Requirements
practice, a device for applying repeated force cycles to a
2.4 NCSL Standard:
specimenorcomponent,whichappliesrepeatedforcecyclesof
Publication 940830/1600 NCSL Glossary of Metrology—
the same span, frequency, waveshape, mean level, and endlev-
Related Terms
els.
3.2.14 force command, n—the desired force to be applied to
3. Terminology
the specimen or dynamometer by the testing machine.
3.1 Terminology used in this practice is in accordance with
3.2.15 force transducer, n—a measuring device that can
Terminology E1823. Definitions provided in this practice are
provide an output signal proportional to the force being
considered either unfamiliar or not included in Terminology
applied.
E1823.
3.2.16 indicated force, n—the force value provided by the
3.2 Definitions:
force transducer or dynamometer’s readout (for example, a
3.2.1 accuracy, n—The quantitative difference between a
numeric or graphical output for reading by a human including
test measurement and a reference value.
a peak picking capability); these values are typically obtained
3.2.2 amplitude, n—one-half the peak-to-peak measurement
from a digital volt meter (DVM) or files generated by a
of the cyclic waveform.
computerized data acquisition.
3.2.3 cal factor, n—the conversion factor between the dy-
3.2.17 instrumentation, n—theelectronicsusedwithatrans-
namometer force and the indicated force.
ducer providing excitation for the transducer, conditioning of
3.2.4 conditioned force, n—the high level voltage or digital the measured signal, and readout of that signal; typically the
data available from the dynamometer or force transducer’s conditioned signal is a voltage and the readout is a numerical
signal conditioning instrumentation; it is frequently of value display or printout.
during dynamic verification as it can be more conveniently
3.2.18 peak, n—the maximum endlevel of a cycle.
monitored by stand alone measurement instrumentation.
3.2.19 peak picking, n—the process of determining the peak
3.2.5 corrected force, n—the force obtained after applying a
or valley of a cyclic waveform.
dynamic correction factor to the force transducer’s indicated
3.2.20 repeatability, n—the closeness of agreement among
force.
repeated measurements of the dynamic forces under the same
3.2.6 data acquisition equipment, n—the equipment used to
conditions.
convert a conditioned force to an indicated force.
3.2.21 span, n—the absolute value of the peak minus the
3.2.7 dynamic dynamometer forces, n—the maximum and
valley for a cyclic waveform.
minimum forces produced in the dynamometer during a
3.2.22 transducer, n—a measuring device which has an
portion of a dynamic test.
output signal proportional to the engineering quantity being
3.2.8 dynamic errors, n—errors in the force transducer’s
measured.
corrected force output that occur due to dynamic operation
3.2.23 true force, n—the actual force applied to the speci-
(with specimen bending errors intentionally corrected out).
men or dynamometer.
3.2.9 dynamic indicated forces, n—the maximum and mini-
3.2.24 valley, n—the minimum endlevel of a cycle.
mum forces reported by the test machine during a portion of a
dynamic test. These values are typically obtained using an
4. Significance and Use
oscilloscope, peak-valley meter, or files generated by comput-
4.1 It is well understood how to measure the forces applied
erized data acquisition.
to a specimen under static conditions. Practices E4 details the
3.2.10 dynamometer, n—an elastic calibration device used
required process for verifying the static force measurement
toindicatetheforcesappliedbyafatiguetestingsystemduring
capabilities of testing machines. During dynamic operation
dynamic operation. A strain gaged specimen is often used as
however, additional errors may manifest themselves in a
the dynamometer. Suitable transducer instrumentation is also
testing machine. Further verification is necessary to confirm
required to provide accurate readings over the intended fre-
the dynamic force measurement capabilities of testing ma-
chines.
NOTE 1—The static machine verification accomplished by Practices E4
Available from the U.S. Government Printing Office, Washington, DC 20402.
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St., simply establishes the reference. Indicated forces measured from the force
4th Floor, New York, NY 10036, http://www.ansi.org. cell are compared with the dynamometer conditioned forces statically for
E467−08 (2014)
confirmation and then dynamically for dynamic verification of the fatigue
5.2 Dynamometer Instrumentation—Dynamometer instru-
testing system’s force output.
mentation is also required. The overall accuracy of the dyna-
NOTE 2—The dynamic accuracy of the force cell’s output will not
mometer and the associated instrumentation shall contribute
always meet the accuracy requirement of this standard without correction.
less than 25 % of the total error of the dynamic measurement
Dynamic correction to the force cell output can be applied provided that
being made. Refer to Annex A2 for guidance on suitable
verification is performed after the correction has been applied.
NOTE 3—Overall test accuracy is a combination of measurement
instrumentation for both the dynamometer and the machine
accuracy and control accuracy.This practice provides methods to evaluate
beingverified.Calibrationofthedynamometerinstrumentation
either or both. As control accuracy is dependent on many more variables
must be current and traceable to the National Institute of
than measurement accuracy it is imperative that the test operator utilize
Standards and Technology (NIST) or some other recognized
appropriate measurement tools to confirm that the testing machine’s
control behavior is consistent between verification activities and actual national standards organization.
testing activities.
5.3 Dynamometer Static Calibration—An absolute calibra-
4.2 Dynamic errors are primarily span dependent, not level
tion of the dynamometer as tested in accordance with Practices
dependent. That is, the error for a particular force endlevel
E4isnotrequired.Itisonlynecessarytostaticallycalibratethe
during dynamic operation is dependent on the immediately
dynamometer indicated forces to the force transducer indicated
preceding force endlevel. Larger spans imply larger absolute
forces at the force levels corresponding to the desired dynamic
errors for the same force endlevel.
forceendlevels.Itisthisrelationshipthatwillbeverifiedunder
4.3 Due to the many test machine factors that influence dynamic conditions to assure acceptable levels of additional
dynamic force accuracy, verification is recommended for every errors due to dynamic operation. Details of the static calibra-
new combination of potential error producing factors. Primary tion of the dynamometer are included in Section 6 as an
factors are specimen design, machine configuration, test integral part of the practice.
frequency, and loading span. Clearly, performing a full verifi-
cation for each configuration is often impractical. To address
6. Procedure—Full Verification
this problem, dynamic verification is taken in two parts.
NOTE 6—The objective of a full verification is to show that the force
transducercorrectedforceaccuracyiswithinanacceptablerangewhenall
4.3.1 First, one or more full verifications are performed at
sources of dynamic error have been taken into account.
least annually. The main body of this practice describes that
procedure. This provides the most accurate estimate of dy-
6.1 Designing the Test—Prepare a matrix of configurations,
namic errors, as it will account for electronic as well as
test frequencies, and loading spans which address the follow-
acceleration-induced sources of error.
ing issues:
4.3.2 The second part, described in Annex A1, is a simpli-
6.1.1 Machine Configurations—Ideally, the machine should
fied verification procedure. It provides a simplified method of
be configured exactly as it will be used for material testing
estimating acceleration-induced errors only. This procedure is
including grips or fixturing, or both.Where it is not practical to
to be used for common configuration changes (that is,
test all expected configurations, test the configuration(s) with
specimen/grip/crosshead height changes).
the largest expected acceleration errors. In this case, AnnexA1
must be used to verify additional test set-ups. It is recom-
4.4 Dynamic verification of the fatigue system is recom-
mended that at least two machine configurations be verified,
mended over the entire range of force and frequency over
and that the ability to detect acceleration errors against the true
which the planned fatigue test series is to be performed.
errors measured with the full verifications be tested.
Endlevels are limited to the machine’s verified static force as
6.1.2 Test Frequencies—Where the testing machine will
defined by the current static force verification when tested in
only be used at a few discrete frequencies, perform the
accordance with Practices E4.
verification at those fre
...
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.
´1
Designation: E467 − 08 E467 − 08 (Reapproved 2014)
Standard Practice for
Verification of Constant Amplitude Dynamic Forces in an
Axial Fatigue Testing System
This standard is issued under the fixed designation E467; 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.
ε NOTE—3.2.1 and 3.2.15 were editorially revised in December 2011.
1. Scope
1.1 This practice covers procedures for the dynamic verification of cyclic force amplitude control or measurement accuracy
during constant amplitude testing in an axial fatigue testing system. It is based on the premise that force verification can be done
with the use of a strain gaged elastic element. Use of this practice gives assurance that the accuracies of forces applied by the
machine or dynamic force readings from the test machine, at the time of the test, after any user applied correction factors, fall
within the limits recommended in Section 9. It does not address static accuracy which must first be addressed using Practices E4
or equivalent.
1.2 Verification is specific to a particular test machine configuration and specimen. This standard is recommended to be used
for each configuration of testing machine and specimen. Where dynamic correction factors are to be applied to test machine force
readings in order to meet the accuracy recommended in Section 9, the verification is also specific to the correction process used.
Finally, if the correction process is triggered or performed by a person, or both, then the verification is specific to that individual
as well.
1.3 It is recognized that performance of a full verification for each configuration of testing machine and specimen configuration
could be prohibitively time consuming and/or expensive. Annex A1 provides methods for estimating the dynamic accuracy impact
of test machine and specimen configuration changes that may occur between full verifications. Where test machine dynamic
accuracy is influenced by a person, estimating the dynamic accuracy impact of all individuals involved in the correction process
is recommended. This practice does not specify how that assessment will be done due to the strong dependence on owner/operators
of the test machine.
1.4 This practice is intended to be used periodically. Consistent results between verifications is expected. Failure to obtain
consistent results between verifications using the same machine configuration implies uncertain accuracy for dynamic tests
performed during that time period.
1.5 This practice addresses the accuracy of the testing machine’s force control or indicated forces, or both, as compared to a
dynamometer’s indicated dynamic forces. Force control verification is only applicable for test systems that have some form of
indicated force peak/valley monitoring or amplitude control. For the purposes of this verification, the dynamometer’s indicated
dynamic forces will be considered the true forces. Phase lag between dynamometer and force transducer indicated forces is not
within the scope of this practice.
1.6 The results of either the Annex A1 calculation or the full experimental verification must be reported per Section 10 of this
standard.
1.7 This practice provides no assurance that the shape of the actual waveform conforms to the intended waveform within any
specified tolerance.
1.8 This standard is principally focused at room temperature operation. It is believed there are additional issues that must be
addressed when testing at high temperatures. At the present time, this standard practice must be viewed as only a partial solution
for high temperature testing.
1.9 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
This practice is under the jurisdiction of ASTM Committee E08 on Fatigue and Fractureand is the direct responsibility of Subcommittee E08.03 on Advanced Apparatus
and Techniques.
Current edition approved Nov. 1, 2008May 1, 2014. Published January 2009September 2014. Originally approved in 1972. Last previous edition approved in 20042008
ε1
as E4E46767 – 98a–08 (2004). . DOI: 10.1520/E0467-08.10.1520/E0467-08R14.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E467 − 08 (2014)
1.10 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
2.1 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E1823 Terminology Relating to Fatigue and Fracture Testing
E1942 Guide for Evaluating Data Acquisition Systems Used in Cyclic Fatigue and Fracture Mechanics Testing
2.2 Military Standard:
1312-B Fastener Test Methods
2.3 ANSI Standard:
Z540-1-1994 Calibration Laboratories and Measuring and Test Equipment—General Requirements
2.4 NCSL Standard:
Publication 940830/1600 NCSL Glossary of Metrology—Related Terms
3. Terminology
3.1 Terminology used in this practice is in accordance with Terminology E1823. Definitions provided in this practice are
considered either unfamiliar or not included in Terminology E1823.
3.2 Definitions:
3.2.1 accuracy, n—The quantitative difference between a test measurement and a reference value.
3.2.2 amplitude, n—one-half the peak-to-peak measurement of the cyclic waveform.
3.2.3 cal factor, n—the conversion factor between the dynamometer force and the indicated force.
3.2.4 conditioned force, n—the high level voltage or digital data available from the dynamometer or force transducer’s signal
conditioning instrumentation; it is frequently of value during dynamic verification as it can be more conveniently monitored by
stand alone measurement instrumentation.
3.2.5 corrected force, n—the force obtained after applying a dynamic correction factor to the force transducer’s indicated force.
3.2.6 data acquisition equipment, n—the equipment used to convert a conditioned force to an indicated force.
3.2.7 dynamic dynamometer forces, n—the maximum and minimum forces produced in the dynamometer during a portion of
a dynamic test.
3.2.8 dynamic errors, n—errors in the force transducer’s corrected force output that occur due to dynamic operation (with
specimen bending errors intentionally corrected out).
3.2.9 dynamic indicated forces, n—the maximum and minimum forces reported by the test machine during a portion of a
dynamic test. These values are typically obtained using an oscilloscope, peak-valley meter, or files generated by computerized data
acquisition.
3.2.10 dynamometer, n—an elastic calibration device used to indicate the forces applied by a fatigue testing system during
dynamic operation. A strain gaged specimen is often used as the dynamometer. Suitable transducer instrumentation is also required
to provide accurate readings over the intended frequency and force range. (Refer to Practice E467, Annex A2 for detailed
information about the dynamometer and instrumentation.)
3.2.11 dynamometer force, n—the force value provided by the dynamometer’s readout.
3.2.12 endlevel, n—either a maximum or minimum level for a cyclic waveform.
3.2.13 fatigue testing system, n—for the purpose of this practice, a device for applying repeated force cycles to a specimen or
component, which applies repeated force cycles of the same span, frequency, waveshape, mean level, and endlevels.
3.2.14 force command, n—the desired force to be applied to the specimen or dynamometer by the testing machine.
3.2.15 force transducer, n—a measuring device that can provide an output signal proportional to the force being applied.
3.2.16 indicated force, n—the force value provided by the force transducer or dynamometer’s readout (for example, a numeric
or graphical output for reading by a human including a peak picking capability); these values are typically obtained from a digital
volt meter (DVM) or files generated by a computerized data acquisition.
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.
Available from the U.S. Government Printing Office, Washington, DC 20402.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
E467 − 08 (2014)
3.2.17 instrumentation, n—the electronics used with a transducer providing excitation for the transducer, conditioning of the
measured signal, and readout of that signal; typically the conditioned signal is a voltage and the readout is a numerical display or
printout.
3.2.18 peak, n—the maximum endlevel of a cycle.
3.2.19 peak picking, n—the process of determining the peak or valley of a cyclic waveform.
3.2.20 repeatability, n—the closeness of agreement among repeated measurements of the dynamic forces under the same
conditions.
3.2.21 span, n—the absolute value of the peak minus the valley for a cyclic waveform.
3.2.22 transducer, n—a measuring device which has an output signal proportional to the engineering quantity being measured.
3.2.23 true force, n—the actual force applied to the specimen or dynamometer.
3.2.24 valley, n—the minimum endlevel of a cycle.
4. Significance and Use
4.1 It is well understood how to measure the forces applied to a specimen under static conditions. Practices E4 details the
required process for verifying the static force measurement capabilities of testing machines. During dynamic operation however,
additional errors may manifest themselves in a testing machine. Further verification is necessary to confirm the dynamic force
measurement capabilities of testing machines.
NOTE 1—The static machine verification accomplished by Practices E4 simply establishes the reference. Indicated forces measured from the force cell
are compared with the dynamometer conditioned forces statically for confirmation and then dynamically for dynamic verification of the fatigue testing
system’s force output.
NOTE 2—The dynamic accuracy of the force cell’s output will not always meet the accuracy requirement of this standard without correction. Dynamic
correction to the force cell output can be applied provided that verification is performed after the correction has been applied.
NOTE 3—Overall test accuracy is a combination of measurement accuracy and control accuracy. This practice provides methods to evaluate either or
both. As control accuracy is dependent on many more variables than measurement accuracy it is imperative that the test operator utilize appropriate
measurement tools to confirm that the testing machine’s control behavior is consistent between verification activities and actual testing activities.
4.2 Dynamic errors are primarily span dependent, not level dependent. That is, the error for a particular force endlevel during
dynamic operation is dependent on the immediately preceding force endlevel. Larger spans imply larger absolute errors for the
same force endlevel.
4.3 Due to the many test machine factors that influence dynamic force accuracy, verification is recommended for every new
combination of potential error producing factors. Primary factors are specimen design, machine configuration, test frequency, and
loading span. Clearly, performing a full verification for each configuration is often impractical. To address this problem, dynamic
verification is taken in two parts.
4.3.1 First, one or more full verifications are performed at least annually. The main body of this practice describes that
procedure. This provides the most accurate estimate of dynamic errors, as it will account for electronic as well as
acceleration-induced sources of error.
4.3.2 The second part, described in Annex A1, is a simplified verification procedure. It provides a simplified method of
estimating acceleration-induced errors only. This procedure is to be used for common configuration changes (that is,
specimen/grip/crosshead height changes).
4.4 Dynamic verification of the fatigue system is recommended over the entire range of force and frequency over which the
planned fatigue test series is to be performed. Endlevels are limited to the machine’s verified static force as defined by the current
static force verification when tested in accordance with Practices E4.
NOTE 4—There is uncertainty as to whether or not the vibration in a frame will be different when operating in compression as opposed to tension. As
a consequence, this practice recommends performing verifications at maximum tension and maximum compression endlevels. The total span does not
need to be between those two levels, but can be performed as two tests.
NOTE 5—Primary electronic characteristics affecting dynamic measurement accuracy are noise and bandwidth. Excessive noise is generally the
dominant effect at the minimum test frequency. Insufficient bandwidth-induced errors are generally most significant at the maximum test frequency.
5. Apparatus
5.1 Dynamometer Construction—A dynamometer is required. The strongly preferred dynamometer is an actual specimen,
suitably strain gaged to provide a signal when loaded axially. Where a strain gaged specimen is not practical, an alternative
dynamometer must be made. Annex A2 provides more detailed instructions on the preparation of a typical dynamometer.
5.2 Dynamometer Instrumentation—Dynamometer instrumentation is also required. The overall accuracy of the dynamometer
and the associated instrumentation shall contribute less than 25 % of the total error of the dynamic measurement being made. Refer
to Annex A2 for guidance on suitable instrumentation for both the dynamometer and the machine being verified. Calibration of
the dynamometer instrumentation must be current and traceable to the National Institute of Standards and Technology (NIST) or
some other recognized national standards organization.
E467 − 08 (2014)
5.3 Dynamometer Static Calibration—An absolute calib
...
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