1、Designation: E 467 08Standard 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 the case of revision
2、, 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 control or measu
3、rementaccuracy 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 dynamic force r
4、eadings 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 E4or equivalent.1.2 Verification is specific to a particular test machinec
5、onfiguration 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 also specific to th
6、ecorrection 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 specimen con-figuration
7、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, estimating the dy
8、namic 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-sistent results bet
9、ween 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 or indicated force
10、s, 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 dynamic forces will be
11、 consideredthe true forces. Phase lag between dynamometer and forcetransducer indicated forces is not within the scope of thispractice.1.6 The results of either theAnnexA1 calculation or the fullexperimental verification must be reported per Section 10 ofthis standard.1.7 This practice provides no a
12、ssurance 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. At the presenttime,
13、 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 thesafety concerns,
14、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 Verification of Testin
15、g MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 1823 Terminology Relating to Fatigue and Fracture Test-ingE 1942 Guide for Evaluating Data Acquisition Systems1This practice is under the jurisdiction of ASTM Committee E08 on Fatigue andFracture and is the direct responsibility of
16、 Subcommittee E08.03 on AdvancedApparatus and Techniques.Current edition approved Nov. 1, 2008. Published January 2009. Originallyapproved in 1972. Last previous edition approved in 2004 as E 467 98a (2004).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
17、 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 19428-2959, United States.Used in Cyclic Fatigue and Fracture Mec
18、hanics 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 Terminology used in this pra
19、ctice 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 indicateddynamic force
20、 (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 conversion fa
21、ctor 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 convenientlymonitor
22、ed 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 dynamomet
23、er 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 indicated f
24、orces, 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 usedto indicate
25、 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,AnnexA2 fordetaile
26、d 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 applying rep
27、eated 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 test machine t
28、ransducerwhich 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 provided by thefor
29、ce 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, nthe electronic
30、s 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 picking, nthe proc
31、ess 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 measuring dev
32、ice 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 appliedto a spe
33、cimen under static conditions. Practices E4details 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 confirmthe dynamic f
34、orce measurement capabilities of testing ma-chines.NOTE 1The static machine verification accomplished by Practices E4simply establishes the reference. Indicated forces measured from the forcecell are compared with the dynamometer conditioned forces statically forconfirmation and then dynamically for
35、 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 from American Na
36、tional Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.E467082Dynamic 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 measureme
37、ntaccuracy and control accuracy. This practice provides 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 behavio
38、r is consistent between verification activities and 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 lar
39、ger absoluteerrors for the same force endlevel.4.3 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, test fre-quency, and loa
40、ding span. Clearly, performing a full verifica-tion for each configuration is often impractical. To address 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
41、 provides the most accurate estimate of dy-namic errors, 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 o
42、nly. This procedure isto be used for common configuration 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 li
43、mited to the machines verified static force asdefined 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, th
44、is practice recommends performing verifi-cations at maximum 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
45、. Excessive noise is generally thedominant effect at 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 actualspecim
46、en, suitably strain gaged to provide a signal whenloaded axially. Where a strain gaged specimen is not practical,an alternative dynamometer must be made. Annex A2 providesmore detailed instructions on the preparation of a typicaldynamometer.5.2 Dynamometer InstrumentationDynamometer instru-mentation
47、 is also required. The overall accuracy of the dyna-mometer 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. Cal
48、ibration of the dynamometer instrumentationmust be current 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 Prac
49、ticesE4is not required. It is only necessary to statically calibratethe dynamometer indicated forces to 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 dynamometer are included in Section 6as an integral part of the practice.6. ProcedureFull VerificationNOTE 6The objective of a full verificati
