ASTM D76-1999(2005) Standard Specification for Tensile Testing Machines for Textiles《纺织材料的拉伸试验机》.pdf

1、Designation: D 76 99 (Reapproved 2005)Standard Specification forTensile Testing Machines for Textiles1This standard is issued under the fixed designation D 76; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revisi

2、on.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon (e) 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

3、 force-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 propert

4、ies of textile materials not coveredby this standard are given in the ASTM standards using thosemachines.1.3 The values stated in SI units are to be regarded asstandard; the values in inch-pound units are provided asinformation only and are not exact equivalents.1.4 The following safety hazards cave

5、at pertains only to thetest methods described in this specification: This standard doesnot purport to address all of the safety concerns, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applica

6、bility of regulatory limitations priorto use.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 2256 Test Method for Tensile Properties of Yarns by theSingle-Strand MethodE4 Practices for Force Verification of Testing MachinesE74 Practice of Calibration of Force-Measu

7、ring Instru-ments for Verifying the Force Indication of Testing Ma-chines3. Terminology3.1 Definitions:3.1.1 bench marks, nmarks placed on a specimen todefine gage length, that is, the portion of the specimen that willbe evaluated in a specific test.3.1.2 calibrate, vto determine and record the rela

8、tionshipbetween a set of standard units of measure and the output of aninstrument or test procedure.3.1.2.1 DiscussionThis term is also commonly used todescribe the checking of previously marked instruments, anoperation more properly described as a description of verifi-cation.3.1.3 capacity, nfor t

9、ensile testing machines, the maxi-mum force for which the machine is designed.3.1.3.1 DiscussionCapacity is the maximum force thetester-frame and the drive system can exercise on the specimenwithout inadmissible deformations of the tester-frame, etc.Within its capacity, there are available load-cell

10、s with differentfull-scale-ranges which may be chosen to select an appropriatefull-scale-range for a special test.3.1.4 clamp, nthat part of a testing machine used to gripthe specimen by means of suitable jaws.3.1.5 constant-rate-of-extension (CRE) type tensile testingmachine (CRE), nin tensile test

11、ing, an apparatus in which thepulling clamp moves at a uniform rate, and the force-measuring mechanism moves a negligible distance with in-creasing force, less than 0.13 mm (0.005 in.).3.1.6 constant-rate-of-load tensile testing machine (CRL),nin tensile testing, an apparatus in which the rate of in

12、creaseof the force is uniform with time after the first 3 s and thespecimen is free to elongate, this elongation being dependenton the extension characteristics of the specimen at any appliedforce.3.1.7 constant-rate-of-traverse tensile testing machine(CRT), nin tensile testing, an apparatus in whic

13、h 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 that is usually not constant and is dependent on theextension characteristics of the specimen.

14、3.1.8 effective carriage mass, n in CRL-type tensile test-ing machine, the force actually applied to a specimen by themass of the carriage, plus any added weight.3.1.9 effective gage length, n in tensile testing, the esti-mated length of the specimen subjected to a strain equal to thatobserved for t

15、he true gage length.1This specification is under the jurisdiction of ASTM Committee D13 onTextiles and is the direct responsibility of Subcommittee D13.58 on Yarn TestMethods, General.Current edition approved April 1, 2005. Published June 2005. Originallyapproved in 1920 . Last previous edition appr

16、oved in 1999 as D 76 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Bar

17、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.9.1 DiscussionThe effective gage length can be cal-culated using the following equation:GE5 GN3ENET(1)where:GE= effective gage length,GN= nominal gage length,EN= percent elongation based on nominal gage length,andET= pe

18、rcent elongation based on true gage length.3.1.10 grip, vin tensile testing, to hold, grasp, or secure,for example, to grip the specimen by the jaws of the clamps.3.1.11 jaw face, nin tensile testing machines, the surfaceof a jaw which in the absence of a liner contacts the specimen.3.1.12 jaw liner

19、, nin tensile testing machines, any mate-rial placed between the jaw face and the specimen to improvethe holding power of the jaws.3.1.13 jaws, nin tensile testing machines, the elements ofa clamp which grip the specimen.3.1.14 least count, nin tensile testing machines, the small-est change in the i

20、ndicated property that can customarily bedetermined (see also sensitivity).3.1.14.1 DiscussionIn tensile testing machines with closegraduations for force or elongation indications, the least countmay be the value of a graduation interval; with open gradua-tions, or with magnifiers for reading, the l

21、east count may be anestimated fraction (rarely as fine as 0.1) of a graduationinterval; and with verniers, the least count is ordinarily thedifference between the scale and vernier graduations measuredin terms of scale units. If the indicating mechanism includes astepped detent, the detent action ma

22、y determine the least count.(See also sensitivity, in mechanical systems.)3.1.15 nominal gage length, n in tensile testing,(1) thelength of a specimen under specified pretension measured fromnip-to-nip of the jaws of the holding clamps in their startingposition at the beginning of the test, and incl

23、uding any portionof the specimen in contact with bollard or snubbing surfaces.(2) the length of a specimen under specific pretensionbetween frets, in instruments where the specimen is not held byclamps, for example, in a vibroscope.(3) the length of a specimen measured between the points ofattachmen

24、t to the tabs while under specified pretension.3.1.15.1 DiscussionThe calculated percentage of elonga-tion based on the nominal gage length may be in error due toextension of that part of the specimen which lies between thejaws of the clamps.3.1.16 response time, n in tensile testing machines, theti

25、me required by the indicating or recording device to reflect aninstantaneous change in force, usually 0 to 90% of full scale.3.1.17 sensitivity, n in electronic systems, the minimumchange in the input signal that produces a change in the outputsignal that can be reliably measured.3.1.17.1 Discussion

26、Sometimes the term sensitivity isused for the ratio of the response or change induced in theoutput to a stimulus or change in the input. For this ratio“amplification” is a better term.3.1.18 sensitivity, n in mechanical systems, the smallestchange that can be induced on a material by the system and

27、bereliably measured. (See also least count.)3.1.19 stress, nthe resistance to deformation developedwithin a material subjected to an external force.3.1.20 tensile testing machine, nan apparatus designed toimpart, or transmit, force/extension, or stress/strain, to amaterial and to measure the effect

28、of the action. (See alsoconstant-rate-of-extension tensile testing machine, constant-rate-of-load type tensile testing machine, constant-rate-of-traverse tensile testing machine.)3.1.21 test skein, na small skein which has a prescribedlength of yarn and is used for the determination of lineardensity

29、 or breaking, or both.3.1.22 time-to-break, nthe time interval during which aspecimen is under prescribed conditions of tension and isabsorbing the energy required to reach maximum load.3.1.22.1 DiscussionTime-to-break does not include thetime required to remove slack from the specimen.3.1.23 true g

30、age length, nin tensile testing, a preciselength between welldefined bench marks located on the speci-men while under known tension in the unsupported portionbetween the holding clamps and free from contact with anysnubbing surfaces or other sources which could result innonuniform strain.3.1.24 veri

31、fy, v(1) to determine whether a previouslycalibrated instrument, standard solution, or other standard isstill properly calibrated, (2) to establish that an operation hasbeen completed correctly.3.1.25 For definitions of other textile terms used in thisspecification, refer to Terminology D 123.3.2 Ab

32、breviations:Abbreviations:3.2.1 CREconstant-rate-of-extension.3.2.2 CRLconstant-rate-of-load.3.2.3 CRTconstant-rate-of-traverse.4. Performance Requirements4.1 Individual ASTM methods for tensile testing of textilematerials that prescribe apparatus which conforms to thisspecification shall also inclu

33、de such other detailed specifica-tions as may be necessary to describe the testing 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 a

34、n advancing technology.4.2 Comparison of results from tensile testing machinesoperating 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

35、 significantly.4.2.1 Comparison of test data from machines of the sametype, especially 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 ma

36、y causesignificant differences in results even though uniform proce-dures are employed. Data from different CRE-type testingmachines, however, should not be significantly different.D 76 99 (2005)24.2.2 In any case, all types of tensile testing machines mustsatisfy the accuracy requirements as given

37、in Section 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 thespe

38、cified tolerances.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

39、the established 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 ra

40、te-of-traverse (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 the force-measuringmechanism (load cell) moves a negligible distance with in-creasing force less than 0.13 mm (0.005 in.).5.1.2 CRT-Type

41、A 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 theextension charac

42、teristics 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 Multiple-Purpos

43、e 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 elongation. Preferably a force-elongationcurve shall be recorded graphically, or th

44、e force and elongationdata may be indicated on appropriate scales or displays.5.2.1 Most testing machines record only force-elongationdata. When the capacity of a testing machine is adjusted to fitthe predetermined linear density or cross-sectional area of thespecimen, the force recorded will be str

45、ess. When the machineis adjusted to record extension in terms of unit specimenlength, the chart can be read directly in percent elongation orstrain. When these conditions do not exist, the force-elongationcurve must be converted to obtain stress-strain characteristics.5.2.2 The force-indicating and

46、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 orreferenced herein.5.3 Clamping or Holding DevicesSpecimen clamping orholding device

47、s 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 the pulling axis of the testingmachine and the central axis of a properly mounted s

48、pecimencoincide.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 mechanism; forexample, screw, cam action, pneumatic, or toggle.5.3.4 Clamping surfac

49、es 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 used, 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 conforming to Practice E74are requir