ASTM E467-08e1
(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
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.
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.
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...
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 expe...
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Designation:E467 −08
StandardPractice for
Verification of Constant Amplitude Dynamic Forces in an
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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.
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´ NOTE—3.2.1 and 3.2.15 were editorially revised in December 2011.
1. Scope This practice does not specify how that assessment will be
done due to the strong dependence on owner/operators of the
1.1 This practice covers procedures for the dynamic verifi-
test machine.
cation of cyclic force amplitude control or measurement
accuracy during constant amplitude testing in an axial fatigue
1.4 This practice is intended to be used periodically. Con-
testing system. It is based on the premise that force verification
sistent results between verifications is expected. Failure to
can be done with the use of a strain gaged elastic element. Use
obtain consistent results between verifications using the same
of this practice gives assurance that the accuracies of forces
machine configuration implies uncertain accuracy for dynamic
appliedbythemachineordynamicforcereadingsfromthetest
tests performed during that time period.
machine, at the time of the test, after any user applied
1.5 This practice addresses the accuracy of the testing
correction factors, fall within the limits recommended in
machine’s force control or indicated forces, or both, as
Section 9. It does not address static accuracy which must first
compared to a dynamometer’s indicated dynamic forces. Force
be addressed using Practices E4 or equivalent.
control verification is only applicable for test systems that have
1.2 Verification is specific to a particular test machine
some form of indicated force peak/valley monitoring or am-
configuration and specimen. This standard is recommended to
plitude control. For the purposes of this verification, the
be used for each configuration of testing machine and speci-
dynamometer’s indicated dynamic forces will be considered
men.Wheredynamiccorrectionfactorsaretobeappliedtotest
the true forces. Phase lag between dynamometer and force
machine force readings in order to meet the accuracy recom-
transducer indicated forces is not within the scope of this
mended in Section 9, the verification is also specific to the
practice.
correction process used. Finally, if the correction process is
1.6 TheresultsofeithertheAnnexA1calculationorthefull
triggered or performed by a person, or both, then the verifica-
experimental verification must be reported per Section 10 of
tion is specific to that individual as well.
this standard.
1.3 It is recognized that performance of a full verification
1.7 This practice provides no assurance that the shape of the
for each configuration of testing machine and specimen con-
actual waveform conforms to the intended waveform within
figuration could be prohibitively time consuming and/or ex-
any specified tolerance.
pensive. Annex A1 provides methods for estimating the dy-
namic accuracy impact of test machine and specimen
1.8 Thisstandardisprincipallyfocusedatroomtemperature
configuration changes that may occur between full verifica-
operation. It is believed there are additional issues that must be
tions. Where test machine dynamic accuracy is influenced by a
addressed when testing at high temperatures. At the present
person, estimating the dynamic accuracy impact of all indi-
time, this standard practice must be viewed as only a partial
viduals involved in the correction process is recommended.
solution for high temperature testing.
1.9 The values stated in inch-pound units are to be regarded
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This practice is under the jurisdiction ofASTM Committee E08 on Fatigue and
as standard. No other units of measurement are included in this
Fractureand is the direct responsibility of Subcommittee E08.03 on Advanced
standard.
Apparatus and Techniques.
Current edition approved Nov. 1, 2008. Published January 2009. Originally
1.10 This standard does not purport to address all of the
approved in 1972. Last previous edition approved in 2004 as E467 – 98a (2004).
safety concerns, if any, associated with its use. It is the
DOI: 10.1520/E0467-08.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E467−08
responsibility of the user of this standard to establish appro- 3.2.9 dynamic indicated forces, n—the maximum and mini-
priate safety and health practices and determine the applica- mum forces reported by the test machine during a portion of a
bility of regulatory li
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