1、Designation: E2309/E2309M 16Standard Practices forVerification of Displacement Measuring Systems andDevices Used in Material Testing Machines1This standard is issued under the fixed designation E2309/E2309M; the number immediately following the designation indicates the yearof original adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These practices cover procedures and requirements forthe calibration and verific
3、ation of displacement 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
4、 used for the 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 design
5、ate the displacement-measuring system(s) to beverified.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues
6、from the two systems may result in non-conformancewith the standard.1.4 Displacement values indicated on displays/printouts oftesting machine data systemsbe they instantaneous, delayed,stored, or retransmittedwhich are within the Classificationcriteria listed in Table 1, comply with Practices E2309/
7、E2309M.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 health practices and determine the applica-bility of regulatory limitations prior to use.2. Refer
8、enced Documents2.1 ASTM Standards:2E83 Practice for Verification and Classification of Exten-someter Systems3. Terminology3.1 Definitions:3.1.1 accuracy, ndegree of conformity of a measure to astandard.3.1.2 error, nthe amount of deviation from a standard.3.1.2.1 DiscussionThe word “error” shall be
9、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 Terms Specific to This Standard:3.2.1 calibration, nin the case of displacement measurings
10、ystems 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 capacity range, nin the case of testing machines, therange of displacement for which it is des
11、igned. 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 correct value of the applied displacement.3.2.4 displacement, na movement or measurement
12、 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.1These practices are under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct respo
13、nsibility of Subcommittee E28.01 onCalibration of Mechanical Testing Machines and Apparatus.Current edition approved Jan. 1, 2016. Published February 2016. Originallypublished in 2005. Last previous edition approved in 2011 as E2309/E2309M-05(2011)1. DOI: 10.1520/E2309_E2309M-162For referenced ASTM
14、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 ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM In
15、ternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.6 lower limit of verification 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, th
16、e ratio, expressed as a percent, of the error tothe correct value of the applied displacement.3.2.7.1 DiscussionThe measured 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
17、 displacement data point. Theerror, and the percent error, shall be calculated from this data asfollows:Error 5 A 2 BPercent Error 5 A 2 B!/B# 3100where:A = displacement measured by the machine being verified,mm in., andB = correct value of the applied displacement, mm in., asdetermined by the calib
18、ration device.3.2.8 reference standard, na standard used to measuredisplacement applied by the testing 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 di
19、splacement measuring apparatus of the testing machine orsystem, at any applied displacement. Appendix 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 indica
20、ted by a displacement of apointer, or pen line. The resolution is calculated by multiplyingthe displacement 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 disp
21、lacement indicators(numeric, displays, printouts, etc.), nthe resolution is thesmallest change in 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,
22、for ei-ther type of displacement indicator, fluctuates by more thantwice the resolution, as described 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 resu
23、lts of successive measurements from thesame applied displacement, carried out under the same condi-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,
24、 nthe difference between themean measured displacement obtained for a given applieddisplacement applied 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
25、 displacement to a specimen.3.2.14.1 DiscussionThe instrumentation may be either anelectrical or a 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 indicati
26、on of the machine or systemunder test to that of a standard and reporting results, withoutmaking adjustments.3.2.16 verification displacement, na displacement withtraceability derived from national standards of length with aspecific uncertainty of measurement, which can be applied todisplacement mea
27、suring systems.3.2.17 verified range of displacement, nin the case oftesting machines, the range of 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 m
28、any industries. They may be used in researchlaboratories to determine material properties, and in 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
29、of operation. The accuracy of the displacementvalue shall be traceable to the National Institute of Standardsand Technology (NIST) or another recognized National Labo-ratory. Practices E2309 provides a procedure to verify thesemachines and systems, in order that the measured displacementvalues may b
30、e traceable. A key element to having traceabilityis that the devices used in the verification produce 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
31、 of displacement measuring systems shall have estimatedTABLE 1 Classification 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
32、0.0005 0.25 0.025 0.001 0.5Class B 0.038 0.0015 0.5 0.075 0.003 1.0Class C 0.064 0.0025 1.0 0.125 0.005 2.0Class D 0.13 0.005 1.5 0.25 0.010 3.0E2309/E2309M 162measurement uncertainties. The reported uncertainty of refer-ence standards must be equal to or less than13 the allowableerror for the measu
33、ring 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 measuring systems shall be verified as asystem with the displacement sensing and measuring devices(see 1
34、.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.6.3 A Practices E2309 verification consists of at least twoverification runs of displacement contained in the displa
35、cementrange(s) selected. See 8.1 and 8.2.6.3.1 If the initial verification run produces values withinthe Practices E2309 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 values
36、which are outside of the Practices E2309 requirements, the “asfound” data 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,
37、 and issuance of a new verificationreport.7. Application of Displacement7.1 In the verification of the displacement measuringsystem, approach the displacement test value by applying thetest displacement from a lower value of displacement. Toreduce the error in displacement measurement due to interna
38、lbacklash of the testing machine, associated fixtures and orapparatus, make sure to approach the starting zero position ofthe testing machine from a point less than zero and in thedirection for which the resultant verification data will beacquired. This procedure shall be followed when acquiringdesc
39、ending verification data as well. When acquiring descend-ing verification data apply a displacement greater than thestarting point and adjust the testing machine to re-establish astarting zero position in the direction for which verificationdata is to be acquired.7.2 Displacement measuring systems t
40、hat are used to ac-quire test data in both ascending and descending 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
41、times, with the difference between any twosuccessive displacement value 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.
42、Report all values.8.2 The low limit of displacement measurement must 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 measuringsyste
43、m is sufficient to allow for verification below 10 % ofdisplacement 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 minimumdisplacemen
44、t value in the next higher decade. Starting with theselected minimal 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
45、-ment application ratios. Report all displacement values andtheir percent errors.NOTE 1Example: If full scale is 200 mm 8 in. and the minimalresolution is 0.025 mm 0.001 mm, the minimum verified displacementwould be 5 mm (0.025 200). Two decades of 20 and 200 mm could beselected to cover the displac
46、ement application range. Suitable verificationtest displacement values would then be approximately 5, 10, 15, 20, 50,100, 150, 200 mm. The largest reported error of the two sets of the testruns is the maximum error for the displacement range.9. Preliminary Procedure9.1 Alignment:9.1.1 When fixturing
47、 the calibration device, it is importantto minimize any misalignment. Significant 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 ele
48、ctro-mechanical testing machines.9.2 Temperature Considerations:9.2.1 Where the displacement measuring systems areelectrical, connect the displacement transducer, indicator,interface, etc. using the appropriate cabling used in the actualmachine setup. Turn on power and allow the components towarm up
49、 for a period of time recommended by the manufac-turer. In the absence of any recommendations, allow at least 15min for the components 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 any bias due to temperature effects in theexpanded uncertainty statement associated with the verificationdisplacement values if required.1
