1、Designation: E467 08 (Reapproved 2014)Standard Practice forVerification of Constant Amplitude Dynamic Forces in anAxial Fatigue Testing System1This standard is issued under the fixed designation E467; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers procedures for the dynamic verifi-cation of cyclic force amplitude
3、control or measurementaccuracy during constant amplitude testing in an axial fatiguetesting system. It is based on the premise that force verificationcan be done with the use of a strain gaged elastic element. Useof this practice gives assurance that the accuracies of forcesapplied by the machine or
4、 dynamic force readings from the testmachine, at the time of the test, after any user appliedcorrection factors, fall within the limits recommended inSection 9. It does not address static accuracy which must firstbe addressed using Practices E4 or equivalent.1.2 Verification is specific to a particu
5、lar test machineconfiguration and specimen. This standard is recommended tobe used for each configuration of testing machine and speci-men. Where dynamic correction factors are to be applied to testmachine force readings in order to meet the accuracy recom-mended in Section 9, the verification is al
6、so specific to thecorrection process used. Finally, if the correction process istriggered or performed by a person, or both, then the verifica-tion is specific to that individual as well.1.3 It is recognized that performance of a full verificationfor each configuration of testing machine and specime
7、n con-figuration could be prohibitively time consuming and/or ex-pensive. Annex A1 provides methods for estimating the dy-namic accuracy impact of test machine and specimenconfiguration changes that may occur between full verifica-tions. Where test machine dynamic accuracy is influenced by aperson,
8、estimating the dynamic accuracy impact of all indi-viduals involved in the correction process is recommended.This practice does not specify how that assessment will bedone due to the strong dependence on owner/operators of thetest machine.1.4 This practice is intended to be used periodically. Con-si
9、stent results between verifications is expected. Failure toobtain consistent results between verifications using the samemachine configuration implies uncertain accuracy for dynamictests performed during that time period.1.5 This practice addresses the accuracy of the testingmachines force control o
10、r indicated forces, or both, ascompared to a dynamometers indicated dynamic forces. Forcecontrol verification is only applicable for test systems that havesome form of indicated force peak/valley monitoring or am-plitude control. For the purposes of this verification, thedynamometers indicated dynam
11、ic forces will be consideredthe true forces. Phase lag between dynamometer and forcetransducer indicated forces is not within the scope of thispractice.1.6 The results of either the AnnexA1 calculation or the fullexperimental verification must be reported per Section 10 ofthis standard.1.7 This prac
12、tice provides no assurance that the shape of theactual waveform conforms to the intended waveform withinany specified tolerance.1.8 This standard is principally focused at room temperatureoperation. It is believed there are additional issues that must beaddressed when testing at high temperatures. A
13、t the presenttime, this standard practice must be viewed as only a partialsolution for high temperature testing.1.9 The values stated in inch-pound units are to be regardedas standard. No other units of measurement are included in thisstandard.1.10 This standard does not purport to address all of th
14、esafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Veri
15、fication of Testing Machines1This practice is under the jurisdiction of ASTM Committee E08 on Fatigue andFractureand is the direct responsibility of Subcommittee E08.03 on AdvancedApparatus and Techniques.Current edition approved May 1, 2014. Published September 2014. Originallyapproved in 1972. Las
16、t previous edition approved in 2008 as E467081. DOI:10.1520/E0467-08R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe AS
17、TM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E6 Terminology Relating to Methods of Mechanical TestingE1823 Terminology Relating to Fatigue and Fracture TestingE1942 Guide for Evaluating Data Acquisition Systems Usedin Cy
18、clic Fatigue and Fracture Mechanics Testing2.2 Military Standard:31312-B Fastener Test Methods2.3 ANSI Standard:4Z540-1-1994 Calibration Laboratories and Measuring andTest EquipmentGeneral Requirements2.4 NCSL Standard:4Publication 940830/1600 NCSL Glossary of MetrologyRelated Terms3. Terminology3.1
19、 Terminology used in this practice is in accordance withTerminology E1823. Definitions provided in this practice areconsidered either unfamiliar or not included in TerminologyE1823.3.2 Definitions:3.2.1 accuracy, nThe quantitative difference between atest measurement and a reference value.3.2.2 ampl
20、itude, none-half the peak-to-peak measurementof the cyclic waveform.3.2.3 cal factor, nthe conversion factor between the dy-namometer force and the indicated force.3.2.4 conditioned force, nthe high level voltage or digitaldata available from the dynamometer or force transducerssignal conditioning i
21、nstrumentation; it is frequently of valueduring dynamic verification as it can be more convenientlymonitored by stand alone measurement instrumentation.3.2.5 corrected force, nthe force obtained after applying adynamic correction factor to the force transducers indicatedforce.3.2.6 data acquisition
22、equipment, nthe equipment used toconvert a conditioned force to an indicated force.3.2.7 dynamic dynamometer forces, nthe maximum andminimum forces produced in the dynamometer during aportion of a dynamic test.3.2.8 dynamic errors, nerrors in the force transducerscorrected force output that occur du
23、e to dynamic operation(with specimen bending errors intentionally corrected out).3.2.9 dynamic indicated forces, nthe maximum and mini-mum forces reported by the test machine during a portion of adynamic test. These values are typically obtained using anoscilloscope, peak-valley meter, or files gene
24、rated by comput-erized data acquisition.3.2.10 dynamometer, nan elastic calibration device usedto indicate the forces applied by a fatigue testing system duringdynamic operation. A strain gaged specimen is often used asthe dynamometer. Suitable transducer instrumentation is alsorequired to provide a
25、ccurate readings over the intended fre-quency and force range. (Refer to Practice E467, AnnexA2 fordetailed information about the dynamometer and instrumenta-tion.)3.2.11 dynamometer force, nthe force value provided bythe dynamometers readout.3.2.12 endlevel, neither a maximum or minimum level fora
26、cyclic waveform.3.2.13 fatigue testing system, nfor the purpose of thispractice, a device for applying repeated force cycles to aspecimen or component, which applies repeated force cycles ofthe same span, frequency, waveshape, mean level, and endlev-els.3.2.14 force command, nthe desired force to be
27、 applied tothe specimen or dynamometer by the testing machine.3.2.15 force transducer, na measuring device that canprovide an output signal proportional to the force beingapplied.3.2.16 indicated force, nthe force value provided by theforce transducer or dynamometers readout (for example, anumeric o
28、r graphical output for reading by a human includinga peak picking capability); these values are typically obtainedfrom a digital volt meter (DVM) or files generated by acomputerized data acquisition.3.2.17 instrumentation, nthe electronics used with a trans-ducer providing excitation for the transdu
29、cer, conditioning ofthe measured signal, and readout of that signal; typically theconditioned signal is a voltage and the readout is a numericaldisplay or printout.3.2.18 peak, nthe maximum endlevel of a cycle.3.2.19 peak picking, nthe process of determining the peakor valley of a cyclic waveform.3.
30、2.20 repeatability, nthe closeness of agreement amongrepeated measurements of the dynamic forces under the sameconditions.3.2.21 span, nthe absolute value of the peak minus thevalley for a cyclic waveform.3.2.22 transducer, na measuring device which has anoutput signal proportional to the engineerin
31、g quantity beingmeasured.3.2.23 true force, nthe actual force applied to the speci-men or dynamometer.3.2.24 valley, nthe minimum endlevel of a cycle.4. Significance and Use4.1 It is well understood how to measure the forces appliedto a specimen under static conditions. Practices E4 details therequi
32、red process for verifying the static force measurementcapabilities of testing machines. During dynamic operationhowever, additional errors may manifest themselves in atesting machine. Further verification is necessary to confirmthe dynamic force measurement capabilities of testing ma-chines.NOTE 1Th
33、e static machine verification accomplished by Practices E4simply establishes the reference. Indicated forces measured from the forcecell are compared with the dynamometer conditioned forces statically for3Available from the U.S. Government Printing Office, Washington, DC 20402.4Available from Americ
34、an National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.E467 08 (2014)2confirmation and then dynamically for dynamic verification of the fatiguetesting systems force output.NOTE 2The dynamic accuracy of the force cells output will notalways meet the a
35、ccuracy requirement of this standard without correction.Dynamic correction to the force cell output can be applied provided thatverification is performed after the correction has been applied.NOTE 3Overall test accuracy is a combination of measurementaccuracy and control accuracy. This practice prov
36、ides methods to evaluateeither or both. As control accuracy is dependent on many more variablesthan measurement accuracy it is imperative that the test operator utilizeappropriate measurement tools to confirm that the testing machinescontrol behavior is consistent between verification activities and
37、 actualtesting activities.4.2 Dynamic errors are primarily span dependent, not leveldependent. That is, the error for a particular force endlevelduring dynamic operation is dependent on the immediatelypreceding force endlevel. Larger spans imply larger absoluteerrors for the same force endlevel.4.3
38、Due to the many test machine factors that influencedynamic force accuracy, verification is recommended for everynew combination of potential error producing factors. Primaryfactors are specimen design, machine configuration, testfrequency, and loading span. Clearly, performing a full verifi-cation f
39、or each configuration is often impractical. To addressthis problem, dynamic verification is taken in two parts.4.3.1 First, one or more full verifications are performed atleast annually. The main body of this practice describes thatprocedure. This provides the most accurate estimate of dy-namic erro
40、rs, as it will account for electronic as well asacceleration-induced sources of error.4.3.2 The second part, described in Annex A1, is a simpli-fied verification procedure. It provides a simplified method ofestimating acceleration-induced errors only. This procedure isto be used for common configura
41、tion changes (that is,specimen/grip/crosshead height changes).4.4 Dynamic verification of the fatigue system is recom-mended over the entire range of force and frequency overwhich the planned fatigue test series is to be performed.Endlevels are limited to the machines verified static force asdefined
42、 by the current static force verification when tested inaccordance with Practices E4.NOTE 4There is uncertainty as to whether or not the vibration in aframe will be different when operating in compression as opposed totension. As a consequence, this practice recommends performing verifi-cations at m
43、aximum tension and maximum compression endlevels. Thetotal span does not need to be between those two levels, but can beperformed as two tests.NOTE 5Primary electronic characteristics affecting dynamic measure-ment accuracy are noise and bandwidth. Excessive noise is generally thedominant effect at
44、the minimum test frequency. Insufficient bandwidth-induced errors are generally most significant at the maximum testfrequency.5. Apparatus5.1 Dynamometer ConstructionA dynamometer is re-quired. The strongly preferred dynamometer is an actualspecimen, suitably strain gaged to provide a signal whenloa
45、ded axially. Where a strain gaged specimen is not practical,an alternative dynamometer must be made. AnnexA2 providesmore detailed instructions on the preparation of a typicaldynamometer.5.2 Dynamometer InstrumentationDynamometer instru-mentation is also required. The overall accuracy of the dyna-mo
46、meter and the associated instrumentation shall contributeless than 25 % of the total error of the dynamic measurementbeing made. Refer to Annex A2 for guidance on suitableinstrumentation for both the dynamometer and the machinebeing verified. Calibration of the dynamometer instrumentationmust be cur
47、rent and traceable to the National Institute ofStandards and Technology (NIST) or some other recognizednational standards organization.5.3 Dynamometer Static CalibrationAn absolute calibra-tion of the dynamometer as tested in accordance with PracticesE4 is not required. It is only necessary to stati
48、cally calibrate thedynamometer indicated forces to the force transducer indicatedforces at the force levels corresponding to the desired dynamicforce endlevels. It is this relationship that will be verified underdynamic conditions to assure acceptable levels of additionalerrors due to dynamic operat
49、ion. Details of the static calibra-tion of the dynamometer are included in Section 6 as anintegral part of the practice.6. ProcedureFull VerificationNOTE 6The objective of a full verification is to show that the forcetransducer corrected force accuracy is within an acceptable range when allsources of dynamic error have been taken into account.6.1 Designing the TestPrepare a matrix of configurations,test frequencies, and loading spans which address the follow-ing issues:6.1.1 Machine ConfigurationsIdeally, the machine shouldbe config
