ASTM E2658-2011 Standard Practices for Verification of Speed for Material Testing Machines《材料试验机速度验证的标准操作规程》.pdf

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1、Designation: E2658 11Standard Practices forVerification of Speed for Material Testing Machines1This standard is issued under the fixed designation E2658; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A

2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These practices cover procedures and requirements forthe calibration and verification of testing machine speed bymeans of standard cali

3、bration devices. This practice is notintended to be complete purchase specifications for testingmachines.1.2 These practices apply to the verification of the speedapplication and measuring systems associated with the testingmachine, such as a scale, dial, marked or unmarked recorderchart, digital di

4、splay, setting, etc. In all cases the buyer/owner/user must designate the speed-measuring system(s) to beverified.1.3 These practices give guidance, recommendations, andexamples, specific to electro-mechanical testing machines. Thepractice may also be used to verify actuator speed for hydraulictesti

5、ng machines.1.4 This standard cannot be used to verify cycle counting orfrequency related to cyclic fatigue testing applications.1.5 Since conversion factors are not required in this prac-tice, either SI units (mm/min), or English in/min, can be usedas the standard.1.6 Speed measurement values and o

6、r settings on displays/printouts of testing machine data systems-be they instanta-neous, delayed, stored, or retransmitted-which are within theClassification criteria listed in Table 1, comply with PracticesE2658.1.7 This standard does not purport to address all of thesafety concerns, if any, associ

7、ated 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:2E2309 Practices for Verification of Displacement Measur-ing

8、 Systems and Devices Used in Material Testing Ma-chines3. Terminology3.1 Definitions:3.1.1 percent error, nin the case of a speed measuringsystem, the ratio, expressed as a percent, of the error to thereference value of the applied speed.3.1.1.1 DiscussionThe speed, as measured by the testingmachine

9、, and the speed, as computed from the readings of thecalibration devices, shall be recorded at each verified speed.The percent error, shall be calculated from this data as follows:Percent Error 5 TMsp 2 Refsp!/Refsp 3 100 (1)where:TMsp = speed measured by the machine being verified,mm/min in/min, an

10、dRefsp = reference value of the measured speed, mm/minin/min, as determined by the calibration device.Not all testing machines have available indicated speed values.In such cases, the verification of the testing machines speedsetting is applicable. The percent error for the testing machinespeed sett

11、ings, shall be calculated as follows:Percent Error 5 TMsps 2 Refsp!/Refsp 3 100 (2)where:TMsps = testing machine speed setting, mm/min (in/min),andRefsp = reference value of the measured speed, mm/min(in/min), as determined by the calibration device.3.1.2 ramp-to-speed condition, nduring a speed ver

12、ifica-tion run, it is the time and or change in displacement requiredto achieve a constant speed condition.3.1.3 reference standards, ndevices used to verify eitherthe speed of a testing machine or the speed indicated by atesting machine.3.1.4 speed measuring system, na device or set of devicescompr

13、ising of a speed transducer and associated instrumenta-tion or a displacement transducer with associated timer andinstrumentation.1These practices are under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.01 onCalibration of Mechanical

14、 Testing Machines and Apparatus.Current edition approved Feb. 1, 2011. Published February 2011. DOI: 10.1520/E265811.2For 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

15、 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.3.1.5 tolerance, nthe allowable deviation from a refer-ence value.3.1.6 speed, ndisplacement divided by time expressed interms of

16、 millimeters/minute, inches/minute, etc.3.1.7 verification speed, na speed with traceability de-rived from national standards of length and time, with aspecific uncertainty of measurement, which can be applied tospeed measuring systems.4. Significance and Use4.1 Material testing requires repeatable

17、and predictabletesting machine speed. The speed measuring devices integral tothe testing machines may be used for measurement of cross-head speed over a defined range of operation. The accuracy ofthe speed value shall be traceable to a National or InternationalStandards Laboratory. Practices E2658 p

18、rovides procedures toverify testing machines, in order that the indicated speed valuesmay be traceable. A key element to having traceability is thatthe devices used in the verification produce known speedcharacteristics, and have been calibrated in accordance withadequate calibration standards.4.2 V

19、erification of testing machine speed at a minimumconsists of either or both of the following options:4.2.1 Verifying the capability of the testing machine tomove the crosshead at the speed selected.4.2.2 Verifying the capability of the testing machine toadequately indicate the speed of the crosshead

20、.4.3 Where applicable, determine the testing machinesramp-to-speed condition. This condition can be significantespecially when verifying fast speeds or testing conditions withvery short testing durations.4.4 This procedure will establish the relationship betweenthe actual crosshead speed and the tes

21、ting machine indicatedspeed and or selected setting. It is this relationship that willallow confidence in the reported displacement over time dataacquired by the testing machine during use.NOTE 1Many material tests never reach the desired test speed. Unlessthe actual data from the material test is e

22、xamined, it is often impossible toknow if the test speed has been reached or is repeatable from test to test.5. Calibration Devices5.1 Reference standards used for verification of speedmeasuring systems shall have estimated measurement uncer-tainties. The measurement uncertainty of verification resu

23、lts,contain the combination of the uncertainty of the displacementcalibration device and time indicating device. The combinedestimate of uncertainty for the reference standards shall beequal to or less than13 the allowable error for the measuringsystem. The estimated measurement uncertainty of the r

24、efer-ence standards should have a confidence level of 95% (k=2).5.2 It is recommended that the testing machine have itsdisplacement measuring systems verified in compliance withPractices E2309 prior to performing this verification. Often thesame displacement calibration devices can be used to perfor

25、mPractices E2309 and this practice. It may be possible to attachthe Displacement Calibration Device one time and performboth verification practices.5.3 Displacement Calibration Devices:5.3.1 Digital Linear Scales and Displacement MeasuringTransducersThese devices typically have sufficient resolu-tio

26、n and accuracy to perform verification of all speed settings.It is important to assess the minimum measurement capabilityof the device. At very slow speeds it may take considerabletime to reach an end displacement value that is adequate for theuse of the device.5.3.1.1 These devices may also have th

27、e capability to beautomated.5.4 Time Indicating Devices5.4.1 Time pieces such as quartz wrist and stop watches canbe used for slower speed settings. The time piece shall have acalibration traceable to a national metrology institute. For mostpurposes, a time piece with an accuracy of 60.02% (approxi-

28、mately 2 second in 3 hours) is sufficient. The uncertainty of thecalibration of the time piece shall be at most13 the accuracy ofthe time piece and shall not significantly contribute to theuncertainty of the speed measurement. See NIST SpecialPublication 960-12.3With automated computer software, ac-

29、curacies of 60.01 seconds may be achieved. However, caremust be taken in designing such systems to avoid errors due tothings such as timer resolution, programming language limita-tions, competing interrupts and processes, etc. Third partysoftware is available to track and adjust the computer clockre

30、ferenced to NIST.6. System Verification6.1 Speed measuring systems shall be verified as a systemwith the speed sensing and measuring devices in place andoperating as in actual use.6.2 System verification is invalid if the speed sensingdevices are removed and checked independently of the testingmachi

31、ne.6.3 The verification shall consist of at least two verificationruns of speed derived data per selected testing machine speedsetting.6.3.1 If the initial verification run produces any percenterror values outside applicable specifications, the “as found”data may be reported and may be used in accor

32、dance withapplicable quality control programs.6.3.2 Adjustments may be made to improve the accuracy ofthe system. They shall be followed by one additional verifica-tion run, and issuance of a new verification report. Typically,making adjustments to improve testing machine speed will3Gust, J.C., Grah

33、am, R.M., Lombardi, M.A. Special Publication 960-12 Stop-watch and Timer Calibrations National Institute of Standards and Technology 2004TABLE 1 Classification of Speed Application Measuring SystemsClassification Resolution% of ReadingAPercent ErrorBClass A 60.25 60.5Class B 60.5 61.0Class C 61.0 62

34、.0Class D 62.5 65.0Class E 65.0 610Class F 610 620AResolution is not criteria for classification when speed application only, isverified.BPercent Error of application or indication of speed.E2658 112influence all speed settings. If an adjustment is made, all testedspeeds must be re-verified unless i

35、t can be demonstrated thatthe adjustment did not affect other speed settings.6.3.3 Quality control programs may require evidence ofrepeatability, reproducibility and reversibility. In such cases itis recommended that a minimum of one speed be verified forrepeatability, reproducibility, and reversibi

36、lity.6.4 The testing machine is verified with the crossheadconfigured to free run with no specimen installed.NOTE 2Testing machine compliance under loading conditions mayintroduce small errors in the displacement measurement data during actualmaterials testing. This error is considered insignificant

37、 relative to thisverification. There are also testing machines where the crosshead speedslows when force is applied. In such cases where it is necessary to verifyspeed of the testing machine under loaded conditions, higher accuracydisplacement calibration devices such as laser interferometer measuri

38、ngsystems, or extensometer type displacement reference standards must beused due to the very small displacements being verified.7. Methods of Verification7.1 Start and Stop Method:7.1.1 This method requires that a set of starting and stoppingdisplacement and time readings be recorded from the displa

39、ce-ment and time calibration devices.7.1.2 In order to obtain data within expected tolerances anassessment of the ramp-to-speed condition may be necessaryso the test run can be started after the crosshead has reached aconstant speed condition.7.1.3 It is best to have testing machine software that ca

40、neasily acquire and report displacement and time data during theverification run for each selected speed.7.1.4 The comparison of the reference start and stop valuesand the data reported by the testing system provides the basisfor verification of speed using this method.7.2 Continuous Acquisition Met

41、hod:7.2.1 This is the preferred method of verifying testingmachine speed.7.2.2 This method requires automated computer software toacquire data from the displacement calibration device.7.2.3 This method can be used to adequately assess theramp-to-speed condition for each speed setting verified.7.2.4

42、This method can show variability in the testing ma-chine speed throughout the verification run.8. Selection of Verification Speed Values8.1 Many testing machines have a selection of presetcrosshead speeds, typically ranging from .025mm/min to10,000mm/minute (.001in/min to 400 in/minute). It is diffi

43、cultand very time consuming to verify every selectable settingavailable with testing machines. Additionally, it is oftenimpossible to adequately verify the fastest speed selectionsbecause displacement calibration devices are typically not longenough to accommodate the displacement necessary. For the

44、sereasons, at a minimum, speeds most commonly used should beselected for verification.Aminimum of two runs of verificationdata for each speed is required.8.1.1 In some cases a testing machine might only be used atone speed with one clutch selected. In such a case only onespeed with two runs of data

45、are all that is required to meet thisstandard.8.2 Many testing machines have multiple clutch selections.If the testing machine is used with multiple clutch settings,speeds for each clutch setting shall be verified even if theselected speed is the same as a selected speed verified with adifferent clu

46、tch setting.8.3 In selecting speeds to be verified, consideration of thetotal displacement and time must be considered. The totaldisplacement must be great enough to allow for the displace-ment calibration devices measurement uncertainty. If thecalibration devices are automated, time is not as criti

47、cal to theoverall measurement uncertainty. But, if a manual Start andStop method is employed, the duration of the verification runmust be long enough to minimize error due to human action.The manual Start and Stop method also requires that the totaldisplacement and duration of the verification run b

48、e longenough to start beyond the ramp to speed condition. SeeAppendix X1.8.4 It is not normal to experience a difference in the speedindication of the testing machine when the crosshead moves inthe opposite direction. However, gravity may contribute to adifference in the ramp to speed condition when

49、 the crossheadis operated in the descending mode. The testing machineshould be verified in the mode of operation normally usedduring testing.9. Preliminary Procedure9.1 Alignment:9.1.1 When attaching the displacement calibration device, itis important to minimize any misalignment. Significant errorscan be induced due to misalignment. Gauge blocks or a squaremay be used to ensure that the displacement calibration deviceoperates perpendicular to the crosshead in electro-mechanicaltesting machines, or in-line or parallel, to the actuator inhydraulic testing