1、Designation: E 2309 05Standard Practices forVerification of Displacement Measuring Systems andDevices Used in Material Testing Machines1This standard is issued under the fixed designation E 2309; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、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 These practices cover procedures and requirements forthe calibration and verification of dis
3、placement measuringsystems by means of standard calibration devices for static andquasi-static testing machines. This practice is not intended tobe complete purchase specifications for testing machines ordisplacement measuring systems. Displacement measuringsystems are not intended to be used for th
4、e determination ofstrain. See Practice E83.1.2 These procedures apply to the verification of the dis-placement measuring systems associated with the testingmachine, such as a scale, dial, marked or unmarked recorderchart, digital display, etc. In all cases the buyer/owner/usermust designate the disp
5、lacement-measuring system(s) to beverified.1.3 Since conversion factors are not required in this prac-tice, either SI units, or inch units, can be used as the standard.1.4 Displacement values indicated on displays/printouts oftesting machine data systemsbe they instantaneous, delayed,stored, or retr
6、ansmittedwhich are within the Classificationcriteria listed in Table 1, comply with Practices E 2309.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and hea
7、lth practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E83 Practice for Verification and Classification of Exten-someters3. Terminology3.1 Definitions:3.1.1 accuracy, ndegree of conformity of a measure to astandard.3.1.2 error
8、, nthe amount of deviation from a standard.3.1.2.1 DiscussionThe word “error” shall be used withnumerical values, for example, “At a displacement of +1.00 in.,the error of the displacement measuring system was +0.001in.”3.1.3 tolerance, nthe allowable deviation from a standard.3.2 Definitions of Ter
9、ms Specific to This Standard:3.2.1 calibration, nin the case of displacement measuringsystems used with testing machines, the process of comparingthe displacement indication of the machine or system under testto that of a standard, making adjustments as needed to meeterror requirements.3.2.2 capacit
10、y range, nin the case of testing machines, therange of displacement for which it is designed. Some testingmachines have more than one capacity range, that is, multipleranges.3.2.3 correction, nin the case of a testing machine, thedifference obtained by subtracting the measured displacementfrom the c
11、orrect value of the applied displacement.3.2.4 displacement, na movement or measurement oflength expressed in terms of millimeters, inches, etc.3.2.5 displacement measuring system, na device or set ofdevices comprised of a displacement transducer and associatedinstrumentation.3.2.6 lower limit of ve
12、rification range, nthe lowest valueof displacement at which a displacement measuring system canbe verified.3.2.7 percent error, nin the case of a displacement mea-suring system, the ratio, expressed as a percent, of the error tothe correct value of the applied displacement.3.2.7.1 DiscussionThe meas
13、ured displacement, as mea-sured by the testing machine, and the applied displacement, ascomputed from the readings of the verification device, shall berecorded at each verification displacement data point. Theerror, and the percent error, shall be calculated from this data asfollows:1These practices
14、 are under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.01 onCalibration of Mechanical Testing Machines and Apparatus.Current edition approved Feb. 1, 2005. Published February 2005.2For referenced ASTM standards, visit the ASTM webs
15、ite, 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 19428-2959, United Stat
16、es.Error 5 A 2 BPercent Error 5 A 2 B!/B# 3 100where:A = displacement measured by the machine being verified,mm (in.), andB = correct value of the applied displacement, mm (in.), asdetermined by the calibration device.3.2.8 reference standard, na standard used to measuredisplacement applied by the t
17、esting machine and measured bythe displacement measuring system to be verified.3.2.9 resolution of the displacement indicator, nsmallestchange of displacement that can be estimated or ascertained onthe displacement measuring apparatus of the testing machine orsystem, at any applied displacement. App
18、endix X1 describes amethod for determining resolution.3.2.10 resolution of analog type displacement indicators(scales, dials, recorders, etc.), nthe resolution is the smallestchange in displacement indicated by a displacement of apointer, or pen line. The resolution is calculated by multiplyingthe d
19、isplacement corresponding to one graduation by the ratioof the width of the pointer or pen line to the center to centerdistance between two adjacent graduation marks.3.2.11 resolution of digital type displacement indicators(numeric, displays, printouts, etc.), nthe resolution is thesmallest change i
20、n displacement that can be displayed on thedisplacement indicator, at any applied displacement. AppendixX1 describes a method for determining resolution.3.2.11.1 DiscussionIf the displacement indication, foreither type of displacement indicator, fluctuates by more thantwice the resolution, as descri
21、bed in 3.2.9 or 3.2.10, theresolution, expressed as displacement, shall be equal to one-half the range of the fluctuation.3.2.12 relative repeatability, nthe closeness of the agree-ment between the results of successive measurements from thesame applied displacement, carried out under the same condi
22、-tions of measurement. It is expressed as percentage of the meanindicated output for the same applied displacement on twosuccessive calibrations for the given displacement.3.2.13 relative reversibility, nthe difference between themean measured displacement obtained for a given applieddisplacement ap
23、plied in an increasing mode and the meanindicated displacement obtained for the same given displace-ment applied in a decreasing mode.3.2.14 testing machine, na mechanical device for apply-ing force and displacement to a specimen.3.2.14.1 DiscussionThe instrumentation may be either anelectrical or a
24、 mechanical device, that is, a scale or pointersystem.3.2.15 verification, nin the case of displacement measur-ing systems used with testing machines, the process of com-paring the displacement indication of the machine or systemunder test to that of a standard and reporting results, withoutmaking a
25、djustments.3.2.16 verification displacement, na displacement withtraceability derived from national standards of length with aspecific uncertainty of measurement, which can be applied todisplacement measuring systems.3.2.17 verified range of displacement, nin the case oftesting machines, the range o
26、f measured displacement forwhich the testing machine gives results within the permissiblevariations specified.4. Significance and Use4.1 Testing machines that apply and measure displacementare used in many industries. They may be used in researchlaboratories to determine material properties, and in
27、productionlines to qualify products for shipment. The displacementmeasuring devices integral to the testing machines may be usedfor measurement of crosshead or actuator displacement over adefined range of operation. The accuracy of the displacementvalue shall be traceable to the National Institute o
28、f Standardsand Technology (NIST) or another recognized National Labo-ratory. Practices E 2309 provides a procedure to verify thesemachines and systems, in order that the measured displacementvalues may be traceable. A key element to having traceabilityis that the devices used in the verification pro
29、duce knowndisplacement characteristics, and have been calibrated in ac-cordance with adequate calibration standards.5. Calibration Devices5.1 Reference standards used for calibration and or verifi-cation of displacement measuring systems shall have estimatedmeasurement uncertainties. The reported un
30、certainty of refer-ence standards must be equal to or less than13 the allowableerror for the measuring system Classification as shown in Table1. The estimated measurement uncertainty of the referencestandard should have a confidence level of 95 % (k = 2).6. System Verification6.1 Displacement measur
31、ing systems shall be verified as asystem with the displacement sensing and measuring devices(see 1.2 and 1.4) in place and operating as in actual use.6.2 System verification is invalid if the displacement sens-ing devices are removed and checked independently of thetesting machine.TABLE 1 Classifica
32、tion of Displacement Measuring SystemsClassificationResolution not to Exceed the Greater of: Error not to Exceed the Greater of:Fixed Error, mm (in.) % of Reading Fixed Error, mm (in.)Relative Error(% of Displacement)Class A 0.013 (0.0005) 60.25 60.025 (0.001) 60.5Class B 0.038 (0.0015) 60.5 60.075
33、(0.003) 61.0Class C 0.064 (0.0025) 61.0 60.125 (0.005) 62.0Class D 0.13 (0.005) 61.5 60.25 (0.010) 63.0E23090526.3 A Practices E 2309 verification consists of at least twoverification runs of displacement contained in the displacementrange(s) selected. See 8.1 and 8.2.6.3.1 If the initial verificati
34、on run produces values withinthe Practices E 2309 requirements of Section 15, the data maybe used “as found” for run one of the two required for the newverification report.6.3.2 If the initial verification run produces any valueswhich are outside of the Practices E 2309 requirements, the “asfound” d
35、ata may be reported and may be used in accordancewith applicable quality control programs.6.3.3 Calibration adjustments may be made to improve theaccuracy of the system. They shall be followed by the tworequired verification runs, and issuance of a new verificationreport.7. Application of Displaceme
36、nt7.1 In the verification of the displacement measuring sys-tem, approach the displacement test value by applying the testdisplacement from a lower value of displacement. To reducethe error in displacement measurement due to internal backlashof the testing machine, associated fixtures and or apparat
37、us,make sure to approach the starting zero position of the testingmachine from a point less than zero and in the direction forwhich the resultant verification data will be acquired. Thisprocedure shall be followed when acquiring descending veri-fication data as well. When acquiring descending verifi
38、cationdata apply a displacement greater than the starting point andadjust the testing machine to re-establish a starting zeroposition in the direction for which verification data is to beacquired.7.2 Displacement measuring systems that are used to ac-quire test data in both ascending and descending
39、directions,shall be verified in both directions.8. Selection of Verification Displacement Values8.1 For any displacement range, verify the displacementmeasuring system by applying at least five test displacementvalues, at least two times, with the difference between any twosuccessive displacement va
40、lue applications being no largerthan one-third the difference between the selected maximumand minimum test displacement values. Applied displacementvalues on the second run are to be approximately the same asthose on the first run. Report all values.8.2 The low limit of displacement measurement must
41、 beequal to or greater than:400 times the resolution for Class A200 times the resolution for Class B100 times the resolution for Class C67 times the resolution for Class D8.2.1 Where the resolution of the displacement measuringsystem is sufficient to allow for verification below 10 % ofdisplacement
42、capacity or range, verify the displacement rangeby applying at least two successive series of displacementvalues, arranged in overlapping decade groups, such that themaximum displacement value in one decade is the minimumdisplacement value in the next higher decade. Starting with theselected minimal
43、 displacement value in each decade, there areto be at least five displacement applications, in an approximateratio of 1:1, 2.5:1, 5:1, 7.5:1, and 10:1, unless the maximumdisplacement value is reached prior to completing all displace-ment application ratios. Report all displacement values andtheir pe
44、rcent errors.NOTE 1Example: If full scale is 200 mm and the minimal resolutionis 0.025 mm, the minimum verified displacement would be 5 mm (0.0253 200). Two decades of 20 and 200 mm could be selected to cover thedisplacement application range. Suitable verification test displacementvalues would then
45、 be approximately 5, 10, 15, 20, 50, 100, 150, 200 mm.The largest reported error of the two sets of the test runs is the maximumerror for the displacement range.9. Preliminary Procedure9.1 Alignment:9.1.1 When fixturing the calibration device, it is importantto minimize any misalignment. Significant
46、 errors can beinduced due to misalignment. Gauge blocks or a square may beused to ensure that the calibration device operates parallel tothe actuator in hydraulic testing machines or perpendicular tothe crosshead in electro-mechanical testing machines.9.2 Temperature Considerations:9.2.1 Where the d
47、isplacement measuring systems are elec-trical, connect the displacement transducer, indicator, interface,etc. using the appropriate cabling used in the actual machinesetup. Turn on power and allow the components to warm up fora period of time recommended by the manufacturer. In theabsence of any rec
48、ommendations, allow at least 15 min for thecomponents to be energized.9.2.2 Position a temperature measuring device in closeproximity to the machine being verified. Allow the displace-ment measuring device and all relevant parts of the verificationequipment to reach thermal stability.9.2.3 Include a
49、ny bias due to temperature effects in theexpanded uncertainty statement associated with the verificationdisplacement values if required.10. Procedure10.1 General:10.1.1 After completing the preliminary procedure given inSection 9 and before commencing with the verification proce-dure, adjust the testing machine to the maximum verificationdisplacement to ensure that the maximum displacement can beachieved, and the machine has adequate space for the calibra-tion device.NOTE 2Care should be given to the way a testing machine is used indetermining the appropri
