1、Designation: D7269/D7269M 11D7269/D7269M 17Standard Test Methods forTensile Testing of Aramid Yarns1This standard is issued under the fixed designation D7269/D7269M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the tensile testing of aramid yarns, cords twisted from such yarns, and fabrics woven from suchcor
3、ds. The yarn or cord may be wound on cones, tubes, bobbins, spools, or beams; may be woven into fabric; or may be in someother form. The methods include testing procedure only and include no specifications or tolerances.1.2 The values stated in either SI units or inch-pound units are to be regarded
4、separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.3 This standard includes the following test methods:SectionBre
5、aking Strength (Force) 11Breaking Tenacity 12Breaking Toughness 17Elongation at Break 13Force at Specified Elongation (FASE) 14Linear Density 10Modulus 15Work-to-Break 16SectionBreaking Force 11Breaking Tenacity 12Breaking Toughness 17Elongation at Break 13Force at Specified Elongation (FASE) 14Line
6、ar Density 10Modulus 15Stress at Break 12Work-to-Break 161.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices a
7、nd determine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommend
8、ations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD1907 Test Method fo
9、r Linear Density of Yarn (Yarn Number) by the Skein MethodD1909 Standard Tables of Commercial Moisture Regains and Commercial Allowances for Textile Fibers1 These test methods are under the jurisdiction of ASTM Committee D13 on Textiles and are the direct responsibility of Subcommittee D13.19 on Ind
10、ustrial Fibers andMetallic Reinforcements.Current edition approved May 1, 2011July 15, 2017. Published June 2011October 2017. Originally approved in 2006. Last previous edition approved in 20102011 asD7269/D7269M10.11. DOI: 10.1520/D7269_D7269M-11.10.1520/D7269_D7269M-17.2 For referencedASTM standar
11、ds, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM
12、 standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published b
13、y ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D2258 Practice for Sampling Yarn for TestingD3800 Test Method for Density of High-Modulus FibersD4848 Terminology Related to Force, Defor
14、mation and Related Properties of TextilesD6587 Test Method for Yarn Number Using Automatic TesterE23 Test Methods for Notched Bar Impact Testing of Metallic Materials3. Terminology3.1 Definitions:3.1.1 slippage, nwith tensile testing, insufficient quality of clamping, resulting in movement of the te
15、st material through thetotal clamping surface. This can be visualized by the movement of markers at the clamp exit, or by sudden changes in thestrain-modulus curves (1st derivative of the strain-stress curve).3.1.2 zero twist, ntwistless, devoid of twist.3.2 The following terms are relevant to this
16、standard: industrial yarn, aramid, breaking force, breaking tenacity, breakingtoughness, chord modulus, elongation, force at specified elongation (FASE), industrial yarn, initial modulus, moisture equilibriumfor testing, aramid, zero twist, standard atmosphere for testing textiles.textiles, work-to-
17、break.3.3 For definitions of terms related to force and deformation in textiles, refer to Terminology D4848.3.4 The following terms are relevant to this standard: breaking force, breaking strength, breaking tenacity, breaking toughness,chord modulus in a stress-strain curve, elongation, force at spe
18、cified elongation (FASE), initial modulus, tensile strength, andwork-to-break.3.4 For definitions of other terms related to textiles, refer to Terminology D123.4. Summary of Test Method4.1 These test methods are used to determine the tensile properties of aramid yarns or cords.4.2 A conditioned or o
19、ven-dried specimen of aramid yarn or cord is clamped in a tensile testing machine and then stretched orloaded until broken. Breaking force, elongation, and force at specified elongation (FASE) are determined directly. Modulus andwork-to-break are calculated from the force-elongation curve. The outpu
20、t of a constant-rate-of-extension (CRE) tensile testingmachine can be connected with electronic recording and computing equipment, which may be programmed to calculate and printthe test results of tensile properties of interest.5. Significance and Use5.1 The levels of tensile properties obtained whe
21、n testing aramid yarns and cords are dependent on the age and history of thespecimen and on the specific conditions used during the test. Among these conditions are rate of stretching, type of clamps,gagegauge length of specimen, temperature and humidity of the atmosphere, rate of airflow across the
22、 specimen, and temperatureand moisture content of the specimen. Testing conditions accordingly are specified precisely to obtain reproducible test results ona specific sample.5.2 Because the force-bearing ability of a reinforced product is related to the strength of the yarn or cord used as a reinfo
23、rcingmaterial, breaking strengthforce is used in engineering calculations when designing various types of textile reinforced products.When needed to compare intrinsic strength characteristics of yarns or cords of different sizes or different types of fiber, breakingtenacity is very useful because, f
24、or a given type of fiber, breaking force is approximately proportional to linear density.5.3 Elongation of yarn or cord is taken into consideration in the design and engineering of reinforced products because of itseffect on uniformity of the finished product and its dimensional stability during ser
25、vice.5.4 The FASE is used to monitor changes in characteristics of the textile material during the various stages involved in theprocessing and incorporation of yarn or cord into a product.5.5 Modulus is a measure of the resistance of yarn or cord to extension as a force is applied. It is useful for
26、 estimating theresponse of a textile reinforced structure to the application of varying forces and rates of stretching. Although modulus may bedetermined at any specified force, initial modulus is the value most commonly used.5.6 Work-to-break is dependent on the relationship of force to elongation.
27、 It is a measure of the ability of a textile structure toabsorb mechanical energy. Breaking toughness is work-to-break per unit mass.5.7 It should be emphasized that, although the preceding parameters are related to the performance of a textile-reinforcedproduct, the actual configuration of the prod
28、uct is significant. Shape, size, and internal construction also can have appreciable effecton product performance. It is not possible, therefore, to evaluate the performance of a textile reinforced product in terms of thereinforcing material alone.5.8 If there are differences of practical significan
29、ce between reported test results for two laboratories (or more), comparativetests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As aD7269/D7269M 172minimum, test samples should be used that are as homogeneous as possible, that a
30、re drawn from the material from which thedisparate test results were obtained, and that are randomly assigned in equal numbers to each laboratory for testing. Other materialswith established test values may be used for this purpose. The test results from the two laboratories should be compared using
31、 astatistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must befound and corrected, or future test results must be adjusted in consideration of the known bias.6. Apparatus6.1 Tensile Testing MachineA single-strand tensile
32、testing machine of the constant rate of extension (CRE) type. The tensiletesting equipment can be either manually operated or can be an automated device. The specifications and methods of calibrationand verification of these machines shall conform to Specification D76. The testing machine tester sha
33、ll be equipped with anautographic recorder (rectilinear coordinates preferred). It is permissible to use tensile testing machines that have a means forcalculating and displaying the required results without the use of an autographic recorder. It is also permissible to use automatedtensile testing eq
34、uipment.electronic data acquisition and data evaluation system.6.1.1 ClampsClamps: Bollard type clamps, in which the specimen is gripped between plane-faced jaws and then makes apartial turn (wrap angle) around a curved extension (or other type of snubbing device) of one jaw before passing to the ot
35、her similarclamp (see Fig. 1). Clamps with a wrap angle of 3.14 rad 180 are recommended for yarns with a linear density up to 10 000decitex 9000 denier. For linear densities above 10 000 decitex 9000 denier, clamps with a wrap angle of 4.71 rad 270 arerequired to prevent slippage.6.1.1.1 Manually Op
36、erated SystemBollard type clamps, in which the specimen is gripped between plane-faced jaws and thenmakes a partial turn (wrap angle) around a curved extension (or other type of snubbing device) of one jaw before passing to theother similar clamp (see Fig. 1 and Fig. 2). Clamps with a wrap angle of
37、180 are required for yarns with a linear density up to3500 decitex 3000 denier. For linear densities above 3500 decitex 3000 denier, clamps with a wrap angle of 270 arerecommended to prevent slippage. See Note 1.6.1.1.2 Automated DeviceUse the clamping system supplied. See Note 1.6.1.1.3 Clamps shal
38、l grip the test specimen without spurious slippage or damage to the test specimen which can result in jawbreaks. The clamps shall maintain constant gripping conditions during the test by means of pneumatic or hydraulic clamps. Thesurface of the jaws in contact with the specimen shall be of a materia
39、l and configuration that minimizes slippage and/or specimenfailure in the clamping zone.6.1.2 Gauge LengthThe gauge length shall be the total length of yarn measured between the clamping point A of the firstclamp and the point B of the second clamp in the starting position (see Fig. 2).NOTE 1The sel
40、ected testing equipment (tester, clamp, gauge length) is known to have an influence on the properties measured (see Section 19, Table8). A method for eliminating the influences introduced by the selected testing equipment is given in Appendix X1.6.1.3 Use a crosshead travel rate in mm/min in./min of
41、 50 % of the nominal gauge length in millimeters inches of thespecimen for para-aramids; 100 %120 % of the nominal gauge length in millimeters inches of the specimen for meta-aramids.7. Sampling7.1 Remove and discard a minimum of 25 m 7527 yd from the outside of the package before taking the sample
42、or anyspecimens.7.2 Yarn:7.2.1 PackagesFor acceptance testing, sample each lot as directed in Practice D2258. Place each laboratory sampling unit ina moisture-proof polyethylene bag or other moisture-proof container to protect the samples from atmospheric changes until readyto condition the samples
43、in the atmosphere for testing aramids. Take the number of specimens for testing specified for the specificproperty measurement to be made.FIG. 1 Principle of Example Bollard Type ClampsD7269/D7269M 1737.2.2 BeamsFor acceptance testing, sample by winding yarns on a tube or spool by means of a winder
44、using a tension of 56 1 mN/tex 0.05 6 0.01 gf/den. Take the yarn from the outside beam layers unless there is a question or disagreement regardingthe shipment; in this case, take the sample only after removing yarn from the beam to a radial depth of 6 mm 14 in. or more tominimize the effects of hand
45、ling and atmospheric changes that may have occurred during shipment or storage. Place eachlaboratory sampling unit in a moisture-proof polyethylene bag or other moisture-proof container to protect the samples fromatmospheric changes until ready to condition the samples in the atmosphere for testing
46、aramids. Take the number of specimens fortesting specified for the specific property measurement to be made.7.3 Cord:7.3.1 Number of Samples and SpecimensThe size of an acceptance sampling lot of tire cord shall be not more than one truckor rail car load or as determined by agreement between the pur
47、chaser and the supplier. Take samples at random from each of anumber of cones, tubes, bobbins, or spools within a lot to be as representative as possible within practical limitations. Make onlyone observation on an individual package for each physical property determination. Take the number of sampl
48、es, therefore, thatwill be sufficient to cover the total number of specimens required for the determination of all physical properties of the tire cord.The recommended number of specimens is included in the appropriate sections of specific test methods covered in this standard.Where such is not spec
49、ified, the number of specimens is as agreed upon between buyer and supplier.7.3.2 Preparation of SamplesIf specimens are not taken directly from the original package, preferably wind the sample on atube or spool by means of a winder using a tension of 5 6 1 mN/tex 0.05 6 0.01 gf/den. If the sample is collected as a looselywound package, or in the form of a skein, some shrinkage invariably will occur, in which case, report that the observed resultswere determined on a relaxed sample. Use care in handling the sample. Discard any sample s
