1、Designation: E1012 14Standard Practice forVerification of Testing Frame and Specimen AlignmentUnder Tensile and Compressive Axial Force Application1This standard is issued under the fixed designation E1012; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, 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. Scope*1.1 Included in this practice are methods covering thedetermination of the amount of
3、bending that occurs during theapplication of tensile and compressive forces to notched andunnotched test specimens during routine testing in the elasticrange. These methods are particularly applicable to the forcelevels normally used for tension testing, creep testing, anduniaxial fatigue testing. T
4、he principal objective of this practiceis to assess the amount of bending exerted upon a test specimenby the ordinary components assembled into a materials testingmachine, during routine tests.2. Referenced Documents2.1 ASTM Standards:2E6 Terminology Relating to Methods of Mechanical TestingE8 Test
5、Methods for Tension Testing of Metallic MaterialsE9 Test Methods of Compression Testing of Metallic Mate-rials at Room TemperatureE21 Test Methods for Elevated Temperature Tension Tests ofMetallic MaterialsE83 Practice for Verification and Classification of Exten-someter SystemsE251 Test Methods for
6、 Performance Characteristics of Me-tallic Bonded Resistance Strain GagesE466 Practice for Conducting Force Controlled ConstantAmplitude Axial Fatigue Tests of Metallic MaterialsE606 Test Method for Strain-Controlled Fatigue TestingE1237 Guide for Installing Bonded Resistance Strain Gages2.2 Other Do
7、cuments:VAMAS Guide 42 A Procedure for the Measurement ofMachine Alignment in Axial Testing3. Terminology3.1 Definitions of Terms Common to Mechanical Testing:3.1.1 For definitions of terms used in this practice that arecommon to mechanical testing of materials, see TerminologyE6.3.1.2 alignment, nt
8、he condition of a testing machine thatinfluences the introduction of bending moments into a speci-men (or alignment transducer) during the application of tensileor compressive forces.3.1.3 eccentricity L, nthe distance between the line ofaction of the applied force and the axis of symmetry of thespe
9、cimen in a plane perpendicular to the longitudinal axis ofthe specimen.3.1.4 reduced section L, nsection in the central portionof the specimen which has a cross section smaller than thegripped ends.3.2 Definitions of Terms Specific to This Standard:3.2.1 axial strain, a, nthe average of the longitud
10、inalstrains measured by strain gages at the surface on oppositesides of the longitudinal axis of symmetry of the alignmenttransducer by multiple strain-sensing devices located at thesame longitudinal position.3.2.1.1 DiscussionThis definition is only applicable to thisstandard. The term is used in o
11、ther contexts elsewhere inmechanical testing.3.2.2 bending strain, b, nthe difference between the strainat the surface and the axial strain (see Fig. 1).3.2.2.1 Discussionin general, the bending strain variesfrom point to point around and along the reduced section of thespecimen. Bending strain is c
12、alculated as shown in Section 10.3.2.3 component (also known as force applicationcomponent), nany of the parts used in the attachment of theload cell or grips to the testing frame, as well as any part,including the grips used in the application of force to thestrain-gaged alignment transducer or the
13、 test specimen.3.2.4 grips, nthat part of the force application componentsthat directly attach to the strain-gage alignment transducer orthe test specimen.3.2.5 microstrain, nstrain expressed in micro-units perunit, such as micrometers/meter or microinches/in.1This practice is under the jurisdiction
14、 of ASTM Committee E28 on MechanicalTesting and is the direct responsibility of Subcommittee E28.01 on Calibration ofMechanical Testing Machines and Apparatus.Current edition approved July 1, 2014. Published August 2014. Originallyapproved in 1989. Last previous edition approved in 2012 as E1012 121
15、. DOI:10.1520/E1012-14.2For 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 the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears
16、at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.6 notched section L, nthe section perpendicular tothe longitudinal axis of symmetry of the specimen where thecross-sectional area is intentionally at a min
17、imum value inorder to serve as a stress raiser.3.2.7 percent bending, PB, (also known as percent bendingstrain), nthe ratio of the bending strain to the axial strainexpressed as a percentage.3.2.8 strain-gaged alignment transducer, nthe transducerused to determine the state of bending and the percen
18、t bendingof a testing frame.3.2.9 Type 1 alignment, nthe condition of a testing ma-chine typically used for static or quasi-static testing includingthe non-rigid components and the positioning of the specimenwithin the grips which can introduce bending moments into thestrain-gaged alignment transduc
19、er or test specimen duringforce application.3.2.10 Type 2 alignment, nthe condition of a testingmachine typically used for dynamic testing and all rigid partsof the load train which can introduce bending moments into thestrain-gaged alignment transducer or test specimen force ap-plication.4. Signifi
20、cance and Use4.1 It has been shown that bending stresses that inadver-tently occur due to misalignment between the applied force andthe specimen axes during the application of tensile andcompressive forces can affect the test results. In recognition ofthis effect, some test methods include a stateme
21、nt limiting themisalignment that is permitted. The purpose of this practice isto provide a reference for test methods and practices thatrequire the application of tensile or compressive forces underconditions where alignment is important. The objective is toimplement the use of common terminology an
22、d methods forverification of alignment of testing machines, associated com-ponents and test specimens.4.2 Alignment verification intervals when required arespecified in the methods or practices that require the alignmentverification. Certain types of testing can provide an indicationof the current a
23、lignment condition of a testing frame with eachspecimen tested. If a test method requires alignmentverification, the frequency of the alignment verification shouldcapture all the considerations i.e. time interval, changes to thetesting frame and when applicable, current indicators of thealignment co
24、ndition through test results.4.3 Whether or not to improve axiality should be a matter ofnegotiation between the material producer and the user.5. Verification of Alignment5.1 A numerical requirement for alignment should specifythe force, strain-gaged alignment transducer dimensions, andtemperature
25、at which the measurement is to be made.Alternatemethods employed when strain levels are of particular impor-tance may be used as described in Practices E466 or E606.When these methods are used, the numerical requirementNOTE 1A bending strain, 6B, is superimposed on the axial strain, a, for low-axial
26、 strain (or stress) in (a) and high-axial strain (or stress) in (b). Forthe same bending strain 6B, a high-percent bending is indicated in (a) and a low-percent bending is indicated in (b).FIG. 1 Schematic Representations of Bending Strains (or Stresses) That May Accompany Uniaxial LoadingE1012 142s
27、hould specify the strain levels, strain-gaged alignment trans-ducer dimensions and temperature at which the measurement isto be made.NOTE 1For a misaligned load train, the percent bending usuallydecreases with increasing applied force. (See Curves A, B, and C in Fig.2.) However, in some severe insta
28、nces, percent bending may increase withincreasing applied force. (See Curve D in Fig. 2.)5.2 For a verification of alignment to be reported in com-pliance with the current revision of E1012 a strain-gagedalignment transducer shall be used. This applies to both Type 1and Type 2 levels of alignment ve
29、rification.5.2.1 This standard defines two types of classified testingmachine alignment per the classification criteria. The type ofalignment shall be noted on the report.5.2.2 When performing an alignment of a testing machinefor the first time or if normally fixed components have beenadjusted or re
30、paired, a mechanical alignment of the testingmachine should be performed. For tensile and fatigueequipment, this step can be accomplished by means of a dialindicator for concentricity alignment adjustment and withprecision shims or feeler gauges with the components broughttogether for angularity ali
31、gnment adjustment. For creep andstress-rupture machines incorporating lever arms, this step maybe accomplished by means of precision shims or feeler gauges,and/or double knife-edge couplings, and/or suitable compo-nents below the lower crosshead of the testing machine. Severedamage may occur to a st
32、rain-gaged alignment transducer ifthis step is omitted. A Mechanical Alignment is a preliminarystep, but is not a substitute for a verification of alignment usinga strain-gaged alignment transducer.5.3 Testing Machine Alignment Type 1A general align-ment verification of the defined load train compon
33、ents. It isunderstood that some parts of the testing machine (i.e. thecrosshead, actuator or grip faces) may be moved or exchangedin normal day to day testing. This alignment verification shouldNOTE 1Curve A: Machine 1, threaded grip ends (1)NOTE 2Curve B: Machine 2, buttonhead grip ends (1)NOTE 3Cu
34、rve C: Machine 3, grips with universal couplings (2)NOTE 4Curve D: schematic representation of a possible response from a concentrically misaligned load train (3)FIG. 2 Effects of Applied Force on Percent Bending for Different Testing Machines and Gripping MethodsE1012 143be conducted for the variou
35、s changes to the system (i.e.adjusting the crosshead and actuator position) to demonstratereproducibility between changing conditions. Whenever pos-sible the alignment verification should be conducted with thetesting system components at a physical position that wouldsimulate the position in which a
36、 test specimen would beinstalled. The strain-gaged alignment transducer geometry andmaterial shall be adequately referenced in the verificationreport.NOTE 2Type 1 typically refers to static test equipment, such as tensile,stress rupture, or creep machines.NOTE 3For creep and stress rupture machines,
37、 the lever arm should bein a level position when performing alignment verification.5.3.1 For some material testing, it is not possible or feasibleto use all parts of the force application components whenverifying alignment. In such cases alternative components maybe used. The use of alternative comp
38、onents shall be adequatelyreferenced in the verification report.5.4 Testing Machine Alignment Type 2Grip-to-grip align-ment verification, where the testing machine mechanical con-figuration is fixed and will not be changed or adjusted duringthe testing period. However, when testing some specimengeom
39、etries, it may be necessary to move the actuator orcrosshead to install the strain-gaged alignment transducerand/or test specimens. This should be avoided if possible, butif it is necessary, care should be taken to reposition the actuatorand or crosshead in the position used during the alignment.Any
40、 removable components specific to the test specimenshould be assembled within the aligned grip set and a strain-gaged alignment transducer used for verification of complianceto E1012.5.4.1 Precision machined grip housings with hydraulic orpneumatically actuated wedge inserts are commonly used inlabo
41、ratory testing. These devices are specifically designed toallow for interchangeability of wedge inserts without adverselyaffecting the alignment of the loading train. For testing systemsusing these gripping configurations, grip wedge inserts may bereplaced with smooth wedge inserts to assess the ali
42、gnment ofthe testing machine under a Type 2 alignment assessment.NOTE 4Type 2 typically refers to dynamic test equipment, such asfatigue testing machines.NOTE 5Type 2 alignment requires as many of the adjustable compo-nents of the testing machine as possible to be positioned in the finalverified pos
43、ition. This could include adjustable reaction components (i.e.crosshead) and actuators, which may otherwise be free to rotate about theloading axis.5.5 Strain-gaged alignment transducers shall be manufac-tured per Section 7 of this standard. The strain-gaged align-ment transducer is to be manufactur
44、ed per section 7.4 asclosely as possible, except that any notches may be eliminated.The same strain-gaged alignment transducer may be used forsuccessive verifications. The materials and design should besuch that only elastic strains occur at the applied forces.5.5.1 Strain-gaged alignment transducer
45、s shall be used forboth Type 1 and Type 2 Testing Machine Alignment.6. Apparatus6.1 This standard requires the use of a strain-gaged align-ment transducer. In some cases it may be helpful to make anassessment using extensometers or alignment componentsemploying mechanical linkages (see Appendix X2),
46、 howeverthese types of strain sensors do not meet the reportingrequirements in Section 11.6.2 In general, repeated force applications to strain levelsapproaching yielding are not good laboratory practice becausethey may affect the subsequently measured results by deform-ing or fatiguing the strain-g
47、aged alignment transducer.6.3 Additional Testing Machine and Force ApplicationComponent Considerations:6.3.1 Poorly made components and multiple interfaces in aload train can cause major difficulty in attempting to align a testsystem. All components in the load train should be machinedwithin precisi
48、on machining practices with attention paid toperpendicularity, concentricity, flatness and surface finish. Thenumber of components should be kept to a minimum.6.3.2 Situations can arise where acceptable alignment can-not be achieved for a given testing machine, set of forceapplication components and
49、 strain-gaged alignment transducer.In these cases, redesign and fabrication of any of the compo-nents may be needed to achieve acceptable alignment.7. Strain-Gaged Alignment Transducer7.1 This practice refers to cylindrical strain-gaged align-ment transducers, thick rectangular strain-gaged alignmenttransducers, and thin rectangular strain-gaged alignment trans-ducers. The actual strain-gaged alignment transducer geometryis dictated by the test standard to be used. These strain-gagedalignment transducers are usually dog-bone shaped with areduced g
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