1、Designation: D76/D76M 11Standard Specification forTensile Testing Machines for Textiles1This standard is issued under the fixed designation D76/D76M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the operating characteristics ofthree types of tensile testing machines used for the determina-tion of the force-
3、elongation properties of textile materials.These types of tensile testing machines are:1.1.1 Constant-rate-of-extension, CRE.1.1.2 Constant-rate-of-traverse, CRT.1.1.3 Constant-rate-of-loading (force), CRL.1.2 Specifications for tensile testing machines to measureother tensile-related properties of
4、textile materials not coveredby this standard are given in the ASTM standards using thosemachines.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 i
5、ndependently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 The following safety hazards caveat pertains only to thetest methods described in this specification: This standard doesnot purport to address all of the safety concerns, if any,associa
6、ted with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD2256 Test Method for Tensi
7、le Properties of Yarns by theSingle-Strand MethodD4849 Terminology Related to Yarns and FibersE4 Practices for Force Verification of Testing MachinesE74 Practice of Calibration of Force-Measuring Instru-ments for Verifying the Force Indication of Testing Ma-chines3. Terminology3.1 For terminology re
8、lated to tensile testing, see Terminol-ogy D4849.3.1.1 The following terms are relevant for this standard:bench marks, calibrate, capacity, clamp, constant-rate-of ex-tension type tensile testing machine (CRE), constant-rate-of-load tensile testing machine (CRL), constant-rate-of-traversetensile tes
9、ting machine (CRT), effective carriage mass, effec-tive gauge length, grip, jaw face, jaw liner, jaws, least count,nominal gauge length, response time, sensitivity, in electronicsystems, sensitivity, stress, tensile testing machine, test skein,time-to-break, true gauge length.3.1.2 For all other ter
10、minology related to textiles, seeTerminology D123.4. Performance Requirements4.1 Individual ASTM methods for tensile testing of textilematerials that prescribe apparatus which conforms to thisspecification shall also include such other detailed specifica-tions as may be necessary to describe the tes
11、ting machine andits operation completely.4.1.1 This specification shall not be construed as beingintended to preclude the evolution of improved methods oftesting or testing apparatus, which is recognized as being vitalin an advancing technology.4.2 Comparison of results from tensile testing machines
12、operating on different principles is not recommended. Whenthese machines are used for comparison testing however,constant time-to-break at 20 6 3 s is the established way ofproducing data, but even then the data may differ significantly.4.2.1 Comparison of test data from machines of the sametype, es
13、pecially two or more CRT-type or two or moreCRL-type machines, requires consideration of the effect ofindividual machine characteristics; for example, inertia effects,capacity, sensitivity, type of loadcell, etc., which may causesignificant differences in results even though uniform proce-dures are
14、employed. Data from different CRE-type testingmachines, however, should not be significantly different.1This specification is under the jurisdiction of ASTM Committee D13 onTextiles and is the direct responsibility of Subcommittee D13.58 on Yarns andFibers.Current edition approved Dec. 1, 2011. Publ
15、ished December 2011. Originallyapproved in 1920 . Last previous edition approved in 2005 as D76 99(2005). DOI:10.1520/D0076_D0076M-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume infor
16、mation, 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.4.2.2 In any case, all types of tensile testing machines mustsatisfy the accuracy requirements as given in Sectio
17、n 7.4.3 While changes in humidity affect the tensile propertiesof many textile materials, changes in humidity normally do notaffect the testing machines themselves.4.4 When machines are moved to different locations, theircalibration shall be verified to make sure that they still meet thespecified to
18、lerances.4.5 When each of the sub-systems (force, extension, clamp-ing) has been individually calibrated, verified, or checked, it isrecommended that the total system be verified using a standardmaterial appropriate for the type testing to be carried out.3Thistesting of the total system is the estab
19、lished way of ensuringthat the clamping system is operating properly.5. Apparatus5.1 Tensile Testing MachinesTensile testing machines fortextile materials are classified according to their operatingprinciple as follows:Type Principle of OperationCRE Constant rate-of-extensionCRT Constant rate-of-tra
20、verse (pendulum type)CRL Constant rate-of-load (inclined plane type)5.1.1 CRE-TypeA testing machine in which the pullingclamp moves at a uniform rate, and when loaded at themaximum allowable force the force-measuring mechanism(load cell) moves a negligible distance of less than 0.13 mm0.005 in.5.1.2
21、 CRT-TypeA testing machine in which the pullingclamp moves at a uniform rate and the force is applied throughthe other clamp, which moves appreciably to actuate a force-measuring mechanism, producing a rate of increase of force orextension which is usually not constant and is dependent on theextensi
22、on characteristics of the specimen.5.1.3 CRL-TypeA testing machine in which the rate ofincrease of the force is uniform with time after the first3sandthe specimen is free to elongate, this elongation being depen-dent upon the extension characteristics of the specimen at anyapplied force.5.1.4 Multip
23、le-Purpose TypeMachines capable of beingoperated as both a CRE-type and a CRL-type may be used.5.2 Measuring DevicesMachines shall be equipped with asuitable device for measuring the force and, when needed, adevice to measure extension. Preferably, the data must beelectronically stored using a data-
24、acquisition system, or at leastthe curve shall be recorded graphically, or the force andextension data may be indicated on appropriate scales ordisplays.5.2.1 Most testing machines record only force-extensiondata. When the capacity of a testing machine is adjusted to fitthe predetermined linear dens
25、ity or cross-sectional area of thespecimen, instead of force the stress will be recorded. Whenthe machine is adjusted to record extension in terms of unitspecimen length, the chart can be read directly in percentelongation or strain. When these conditions do not exist, theforce-extension curve must
26、be converted to obtain stress-straincharacteristics.5.2.2 The force-indicating and force-recording devices shallbe in conformance with the requirements of this specificationas to accuracy, sensitivity, and response time, and shall permitcalibration or verification by appropriate methods described or
27、referenced herein.5.3 Clamping or Holding DevicesSpecimen clamping orholding devices shall be prescribed in the individual testmethods in sufficient detail for all users to employ the same orcomparable devices.5.3.1 The prescribed specimen clamping or holding devicesshall be designed to ensure that
28、the pulling axis of the testingmachine and the central axis of a properly mounted specimencoincide.5.3.2 The clamping or holding device may be designed formanual or automatic mounting of specimens.5.3.3 The required clamping force can be obtained with theclamping or holding devices by any suitable m
29、echanism; forexample, screw, cam action, pneumatic, or toggle.5.3.4 Clamping surfaces in contact with a test specimenshall be of any suitable material and configuration whichprovides the required restraint, preclude slippage, and mini-mize specimen failure in the clamped areas. Clamp liners maybe us
30、ed, provided the above conditions are met.5.3.5 When the flat-faced type clamp proves unsatisfactorybecause of slippage or excessive breakage in the clamp,snubbing type devices (capstan, drum, split-drum, etc.) may beused.5.4 Calibrating DevicesCalibrating weights or other cali-brating devices confo
31、rming to Practice E74 are required forverification of calibration. Calipers, a steel rule that can be readto 0.25 mm 0.01 in., or a suitable cathetometer, and a stopwatch are required for verification of recorded elongation, andcrosshead and chart speed.6. Machine Operational Design6.1 The use of mo
32、tor-driven machines is preferred overmanually driven machines because of improved control oftesting.6.2 Testing machines of the CRT-type shall not be used formeasuring forces below fifty times their resolution. For ex-ample, if the minimum force that can be read is 0.5 cN 0.5 gf,the testing machine
33、may not be used for materials which test at25.0 cN 25 gf or less.6.2.1 Choose the full scale force such that the expectedmaximum force falls within:6.2.1.1 10 to 90% full scale for the CRE-type testingmachines,6.2.1.2 15 to 85% full scale for the CRT-type testingmachines,6.2.1.3 15 to 85% full scale
34、 for the CRL-type testingmachines,6.3 Machines shall operate at a uniform rate of pullingclamp (CRE), and (CRT), or loading (CRL) as specified in 6.4,6.5, and 6.6.6.3.1 Machines may be built for operating at various rates ofoperation or at a single constant rate.3Two styles of standard break fabrics
35、 obtained from Testfabrics, Inc., P.O.Drawer O, Middlesex, NJ 08846 have been found satisfactory for this purpose. Seealso A1.3 of this specification.D76/D76M 1126.3.2 When machines are intended for operation at a speci-fied or required average time to break as specified in individualstandards (for
36、example, 20 s to break as in Test Method D2256and Test Methods D1682) then their rate of operation must beadjustable. The adjustment may be continuous or in steps notexceeding 125:100. Machines with a continuously adjustablerate of operation shall be equipped with a device indicating therate of oper
37、ation.6.3.3 The machine rate of operation shall be within thetolerances prescribed in the individual standards.6.4 CRE-Type:6.4.1 Machines shall be designed for operation at suchuniform rates of pulling clamp as are specified in individualstandards.6.4.2 Using a data-acquisition system, the sampling
38、 rateshould be set to approximately 500/(time-to-break). Using agraphical recording system, the force-measuring system, in-cluding the recording mechanism, shall have a full-scale penresponse time less than2sineither direction. In addition, theresponse time for pen deflections of less than full scal
39、e shall beproportional to the fraction of full-scale time represented bythose deflections within a tolerance of 610 % of the nominalfull-scale response time.NOTE 1The response time of the recording mechanism is the limitingfactor affecting the choice of a rate for testing. The rate chosen shall give
40、the maximum slope of the recorded curve which does not exceed one halfof the slope of the maximum pen speed. See Fig. 1.6.5 CRT-TypeMachines shall be designed for operation ofthe pulling clamp at a uniform rate as specified in individualstandards.6.6 CRL-TypeMachines shall be designed to apply force
41、sat a uniform rate, or at a uniform rate of loading per unit ofspecimen linear density, as specified in individual standards.6.7 Machines may be built for either manual or automaticmounting of the specimen into the clamp or holding devices.7. Tolerance on Indicated Force, Recorded Elongation,Nominal
42、 Gauge Length, and Speed of Moving Clamp7.1 On instruments where the capacity of the force measur-ing mechanism (load cell) is used for digital analysis withoutregard to the full scale force displayed on the recorder, themaximum allowable error in force indication shall be 60.5 %of the reading for C
43、RE-type machines and 61.0 % for CRT-and CRL-type machines (see Section 8).7.2 The maximum allowable error in recorded grip displace-ment shall be 61% of the recorded values for CRE-typemachines and 62.5 mm 0.5 in. for CRT- and CRL-typemachines (see Section 9 for CRE-type machines and Section10 for C
44、RT- and CRL-type machines).7.3 The maximum allowable variation in nominal gaugelength on repeated return of the clamps to their starting positionshall be less than 0.25 mm 0.01 in.7.4 The maximum allowable variation of crosshead speed ofthe CRE-type tester or moving clamp of the CRT-type testerfrom
45、the required testing speed shall be less than 4%.7.5 The maximum allowable variation of the loading ratefor the CRL-type of tester from the required rate shall be lessthan 5 %.8. Verification of Indicated Force8.1 This section provides a general procedure for the veri-fication of the force calibrati
46、on of tensile testing machines fortextiles. No attempt is made to give detailed instructionsapplicable to any particular case. The verification should beperformed or supervised by a qualified person competent toexercise scientific judgment in matters not covered herein.Detailed instructions are give
47、n in Annex A1 covering verifica-tion of one variety of testing machine of the CRL-type.8.2 Verify tensile testing machines as directed in the appli-cable procedure and at the suggested time intervals listed inPractices E4, except as otherwise provided in the followingparagraphs.8.3 Verify the machin
48、e in the condition under which it isused, with all attachments and recording mechanisms inoperation if they are to be used in actual testing; but with anypawls or other detent device in the force-measuring mechanismrendered inoperative. Following the application of each testforce, eliminate the effe
49、ct of friction by gently oscillating theforce-measuring mechanism or by tapping the machine toensure that the applied force is in equilibrium with the forceregistered by the measuring mechanism.8.4 Examine the measuring, indicating, and recordingmechanisms for friction or slack. Estimate, in terms of the unitsin which the machine is calibrated, the magnitude of suchfactors and, if excessive, reduce the error at the source toconform to the tolerance as stated in 7.1.8.5 If other than vertical test forces must be applied, suitableapparatus must be devised subj
