1、Designation: E 467 98a (Reapproved 2004)Standard Practice forVerification of Constant Amplitude Dynamic Forces in anAxial Fatigue Testing System1This standard is issued under the fixed designation E 467; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 amplit
3、ude measurement accuracy duringconstant amplitude testing in an axial fatigue testing system. Itis based on the premise that force verification can be done withthe use of a strain gaged elastic element. Use of this practicegives assurance that the accuracies of dynamic force readingsfrom the test ma
4、chine, at the time of the test, after any userapplied correction factors, fall within the limits recommendedin Section 9. It does not address static accuracy which mustfirst be addressed using Practices E 4 or equivalent.1.2 Verification is specific to a particular test machineconfiguration and spec
5、imen. 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 also specific to thecorrection process u
6、sed. Finally, if the correction process istriggered and/or performed by a person, then the verification isspecific to that individual as well.1.3 It is recognized that performance of a full verificationfor each configuration of testing machine and specimen con-figuration could be prohibitively time
7、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, estimating the dynamic accuracy impact of all
8、 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-sistent results between verifications is expect
9、ed. 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 indicated forces as compared to a dynamometersindicated dyna
10、mic forces. For the purposes of this verification,the dynamometers indicated dynamic forces will be consid-ered the true forces. Phase lag between dynamometer and forcetransducer indicated forces is not within the scope of thispractice.1.6 The results of either the Annex A1 calculation or the fullex
11、perimental verification must be reported per Section 10 ofthis standard.1.7 This standard does not address the issue of a testmachines control accuracy. It does not provide assurance thatthe force obtained equals the force commanded within thespecified accuracy. The correlation being verified is bet
12、weenthe test machines indicated force and the true force on the testspecimen as measured by a dynamometer.1.8 This practice provides no assurance that the shape of theactual waveform conforms to the intended waveform withinany specified tolerance.1.9 This standard is principally focused at room temp
13、eratureoperation. It is believed there are additional issues that must beaddressed when testing at high temperatures. At the presenttime, this standard practice must be viewed as only a partialsolution for high temperature testing.2. Referenced Documents2.1 ASTM Standards:2E 4 Practices for Force Ve
14、rification of Testing MachinesE 6 Terminology Relating to Methods of Mechanical Test-ingE 1823 Terminology Relating to Fatigue and Fracture Test-ingE 1942 Guide for Evaluating Data Acquisition SystemsUsed in Cyclic Fatigue and Fracture Mechanics Testing1This practice is under the jurisdiction of AST
15、M Committee E08 on Fatigue andFracture and is the direct responsibility of Subcommittee E08.03 on AdvancedApparatus and Techniques.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1972. Last previous edition approved in 1998 as E 467 98a.2For referenced ASTM standards
16、, 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 ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19
17、428-2959, United States.2.2 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 Terminology used i
18、n this practice is in accordance withTerminology E 1823. Definitions provided in this practice areconsidered either unfamiliar or not included in TerminologyE 1823.3.2 Definitions:3.2.1 accuracy, nfor the purpose of this practice it shallbe defined as the degree of agreement between the indicateddyn
19、amic force (from the testing machine, after any necessarycorrections have been applied) and dynamic dynamometerforce (from the dynamometer instrumentation). The expectedaccuracy is defined in 9.1.3.2.2 amplitude, none-half the peak-to-peak measurementof the cyclic waveform.3.2.3 cal factor, nthe con
20、version factor between thedynamometer force and the indicated force.3.2.4 conditioned force, nthe high level voltage or digitaldata available from the dynamometer or force transducerssignal conditioning instrumentation; it is frequently of valueduring dynamic verification as it can be more convenien
21、tlymonitored 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 equipment, nthe equipment used toconvert a conditioned force to an indicated force.3.2.7 dynamic
22、 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 due to dynamic operation(with specimen bending errors intentionally corrected out).3.2.9 dynamic i
23、ndicated 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 generated by comput-erized data acquisition.3.2.10 dynamometer, nan elastic calibration device usedt
24、o 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 accurate readings over the intended fre-quency and force range. (Refer to Practice E 467, Annex A
25、2 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 cyclic waveform.3.2.13 fatigue testing system, nfor the purpose of thispractice, a device for
26、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 applied tothe specimen or dynamometer by the testing machine.3.2.15 force transducer, nthe te
27、st machine transducerwhich indicates the applied force by means of an electricalvoltage which can be measured.3.2.15.1 DiscussionTypically the electrical voltage in-creases linearly with applied force. The testing system may usethis voltage for control.3.2.16 indicated force, nthe force value provid
28、ed by theforce transducer or dynamometers readout (for example, anumeric or 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, nth
29、e electronics used with atransducer providing excitation for the transducer, conditioningof the 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 pickin
30、g, nthe process of determining the peakor valley of a cyclic waveform.3.2.20 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 m
31、easuring device which has anoutput signal proportional to the engineering 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 app
32、liedto a specimen under static conditions. Practices E 4 details therequired 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 confir
33、mthe dynamic force measurement capabilities of testing ma-chines.NOTE 1The static machine verification accomplished by Practices E 4simply establishes the reference. Indicated forces measured from the forcecell are compared with the dynamometer conditioned forces statically forconfirmation and then
34、dynamically for dynamic verification of the fatiguetesting systems force output.NOTE 2The dynamic accuracy of the force cells output will notalways meet the accuracy requirement of this standard without correction.3Available from the U.S. Government Printing Office, Washington, DC 20402.4Available f
35、rom American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.E 467 98a (2004)2Dynamic 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 meas
36、urementaccuracy and control accuracy. This practice does not address controlaccuracy. It is up to the test operator to utilize appropriate measurementtools to confirm that the desired forces indicated forces meet the desiredforces within an acceptable degree of accuracy.4.2 Dynamic errors are primar
37、ily 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 Due to the many test machine factors that influencedyna
38、mic force accuracy, verification is recommended for everynew combination of potential error producing factors. Primaryfactors are specimen design, machine configuration, test fre-quency, and loading span. Clearly, performing a full verifica-tion for each configuration is often impractical. To addres
39、s thisproblem, 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 errors, as it will account for electronic as well asaccel
40、eration-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 configuration changes (that is,specimen/grip/crosshead height
41、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 by the current static force verification when tested
42、 inaccordance with Practices E 4.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 maximum tension and maximum compression endlevels. Th
43、etotal 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 the minimum test frequency. Insufficient bandwidth-i
44、nduced 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 whenloaded axially. Where a strain gaged specimen is not pr
45、actical,an alternative dynamometer must be made. Annex A2 providesmore detailed instructions on the preparation of a typicaldynamometer.5.2 Dynamometer InstrumentationDynamometer instru-mentation is also required. The overall accuracy of the dyna-mometer and the associated instrumentation shall cont
46、ributeless 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 current and traceable to the National Institute ofStan
47、dards 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 PracticesE 4 is not required. It is only necessary to statically calibratethe dynamometer indicated forces to
48、 the force transducerindicated forces at the force levels corresponding to the desireddynamic force endlevels. It is this relationship that will beverified under dynamic conditions to assure acceptable levelsof additional errors due to dynamic operation. Details of thestatic calibration of the dynam
49、ometer are included in Section 6as an integral 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 configured exactly as it will be used for material testing
