1、Designation: D2256/D2256M 10 (Reapproved 2015)Standard Test Method forTensile Properties of Yarns by the Single-Strand Method1This standard is issued under the fixed designation D2256/D2256M; the number immediately following the designation indicates theyear of original adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test m
3、ethod covers the determination of tensileproperties of monofilament, multifilament, and spun yarns,either single, plied, or cabled with the exception of yarns thatstretch more than 5.0 % when tension is increased from 0.05 to1.0 cN/tex 0.5 to 1.0 gf/tex.1.2 This test method covers the measurement of
4、 breakingforce and elongation of yarns and includes directions for thecalculation of breaking tenacity, initial modulus, chordmodulus, and breaking toughness.1.2.1 Options are included for the testing of specimens in:(A) straight, (B) knotted, and (C) looped form.1.2.2 Conditions of test are include
5、d for the testing ofspecimens that are: (1) conditioned air, (2) wet, not immersed,(3) wet, immersed, (4) oven-dried, (5) exposed to elevatedtemperature, or (6) exposed to low temperature.NOTE 1Special methods for testing yarns made from specific fibers;namely, glass, flax, hemp, ramie, and kraft pa
6、per and for specific products;namely, tire cords and rope, have been published: Test Methods D885, andSpecification D578.NOTE 2For directions covering the determination of breaking force ofyarn by the skein method refer to Test Method D1578.1.3 The values stated in either SI units or inch-pound unit
7、sare 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 from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address
8、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. Referenced Documents2.1 ASTM Standards:2D76 Specification
9、for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD578 Specification for Glass Fiber StrandsD885 Test Methods for Tire Cords, Tire Cord Fabrics, andIndustrial Filament Yarns Made from ManufacturedOrganic-Base FibersD1578 Test Method for Breaking Strength of Yarn in SkeinF
10、ormD1776 Practice for Conditioning and Testing TextilesD2258 Practice for Sampling Yarn for TestingD2904 Practice for Interlaboratory Testing of a Textile TestMethod that Produces Normally Distributed Data (With-drawn 2008)3D2906 Practice for Statements on Precision and Bias forTextiles (Withdrawn 2
11、008)3D4848 Terminology Related to Force, Deformation andRelated Properties of TextilesD4849 Terminology Related to Yarns and FibersE178 Practice for Dealing With Outlying Observations3. Terminology3.1 Definitions:3.1.1 Refer to Terminology D4848 for definitions of thefollowing terms used in this sta
12、ndard: breaking force, breakingstrength, breaking tenacity, breaking toughness, chordmodulus, elongation, elongation at break, elongation at rupture,initial modulus, knot-breaking force, knot breaking strength,linear density, loop breaking force, loop-breaking strength,single-strand breaking force,
13、single-strand breaking strength,strength and tenacity.3.1.2 Refer to Terminology D123 and Terminology D4849and for definitions of other terms used in this standard.1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.58 on Y
14、arns and Fibers.Current edition approved July 1, 2015. Published September 2015. Originallyapproved in 1964. Last previous edition approved in 2010 as D2256 101. DOI:10.1520/D2256_D2256M-10R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
15、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
16、 PA 19428-2959. United States14. Summary of Test Method4.1 Single-strand yarn specimens are broken on a tensiontesting machine at a predetermined elongation rate and thebreaking force and the elongation at break are determined.Elongation at a specified force or the force or tenacity at aspecified el
17、ongation may also be obtained. Breaking force,breaking tenacity, elongation, initial and chord modulus, andbreaking toughness of the test specimen, in terms of lineardensity, may be calculated from machine scales, dials, record-ing charts, or by an interfaced computer.4.2 This test method offers the
18、 following three physicalconfigurations of the specimen:4.2.1 Configuration A, straight.4.2.2 Configuration B, knotted.4.2.3 Configuration C, looped.4.3 This test method also offers the following six conditionsof test with respect to moisture content of the specimens at thetime of testing:4.3.1 Cond
19、ition 1, conditioned to moisture equilibrium fortesting with standard atmosphere for testing textiles.4.3.2 Condition 2, wet not immersed.4.3.3 Condition 3, wet immersed.4.3.4 Condition 4, oven-dried.4.3.5 Condition 5, high temperature.4.3.6 Condition 6, low temperature.4.4 A test option is specifie
20、d by combining a specimenconfiguration and a moisture content condition, for example,OptionA1 means a straight specimen conditioned and tested ina standard atmosphere for testing textiles.4.5 Unless otherwise indicated, the phrase “single-strandbreaking force” is associated with Option A1.5. Signifi
21、cance and Use5.1 Acceptance TestingOption A1 of Test Method D2256is considered satisfactory for acceptance testing of commercialshipments because the test method has been used extensively inthe trade for acceptance testing. However, this statement is notapplicable to knot and loop breaking force tes
22、ts, tests on wetspecimens, tests on oven-dried specimens, or tests on speci-mens exposed to low or high temperatures and should be usedwith caution for acceptance testing because factual informationon between-laboratory precision and bias is not available.5.1.1 If there are differences of practical
23、significance be-tween reported test results for two laboratories (or more),comparative tests should be performed to determine if there isa statistical bias between them, using competent statisticalassistance. As a minimum, use the samples for such a com-parative tests that are as homogeneous as poss
24、ible, drawn fromthe same lot of material as the samples that resulted in disparateresults during initial testing and randomly assigned in equalnumbers to each laboratory. The test results from the labora-tories involved should be compared using a statistical test forunpaired data, a probability leve
25、l chosen prior to the testingseries. If a bias is found, either its cause must be found andcorrected, or future test results for that material must beadjusted in consideration of the known bias.5.2 Fundamental PropertiesThe breaking tenacity, calcu-lated from the breaking force and the linear densit
26、y, and theelongation are fundamental properties that are widely used toestablish limitations on yarn processing or conversion and ontheir end-use applications. Initial modulus is a measure of theresistance of the yarn to extension at forces below the yieldpoint. The chord modulus is used to estimate
27、 the resistance toimposed strain. The breaking toughness is a measure of thework necessary to break the yarn.5.3 Comparison to Skein TestingThe single-strand methodgives a more accurate measure of breaking force present in thematerial than does the skein method and uses less material. Theskein-break
28、ing force is always lower than the sum of thebreaking forces of the same number of ends broken individu-ally.5.4 ApplicabilityMost yarns can be tested by this testmethod. Some modification of clamping techniques may benecessary for a given yarn depending upon its structure andcomposition. To prevent
29、 slippage in the clamps or damage as aresult of being gripped in the clamps, special clampingadaptations may be necessary with high modulus yarns madefrom fibers such as glass or extended chain polyolefin. Speci-men clamping may be modified as required at the discretion ofthe individual laboratory p
30、roviding a representative force-elongation curve is obtained. In any event, the proceduredescribed in this test method for obtaining tensile propertiesmust be maintained.5.5 Breaking StrengthThe breaking strength of a yarninfluences the breaking strength of fabrics made from the yarn,although the br
31、eaking strength of a fabric also depends on itsconstruction and may be affected by manufacturing operations.5.5.1 Because breaking strength for any fiber-type is ap-proximately proportional to linear density, strands of differentsizes can be compared by converting the observed breakingstrength to br
32、eaking tenacity (centinewtons per tex, grams-force per tex, or grams-force per denier).5.6 ElongationThe elongation of a yarn has an influenceon the manufacturing process and the products made. Itprovides an indication of the likely stretch behavior of garmentareas such as knees, elbows, or other po
33、ints of stress. It alsoprovides design criteria for stretch behavior of yarns or cordsused as reinforcement for items such as plastic products, hose,and tires.5.7 Force-Elongation CurveForce-elongation curves per-mit the calculation of various values, not all of which arediscussed in this test metho
34、d, such as elongation at break,elongation at specified force, force at specified elongation,initial elastic modulus which is resistance to stretching, com-pliance which is ability to yield under stress, and is thereciprocal of the elastic modulus, and area under the curve, ameasure of toughness, whi
35、ch is proportional to the work done.NOTE 3Force-elongation curves can be converted to stress-straincurves if the force is converted to unit stress, such as to centinewtons pertex, or pounds per square inch, or pascals, or grams-force per tex, orgrams-force per denier, and the elongation is based on
36、change per unitlength.D2256/D2256M 10 (2015)25.8 Knot and Loop Breaking ForceThe reduction inbreaking force due to the presence of a knot or loop isconsidered a measure of the brittleness of the yarn. Elongationin knot or loop tests is not known to have any significance andis not usually reported.5.
37、9 Rate of OperationIn general, the breaking force de-creases slightly as time-to-break increases.5.9.1 Operation of CRT, CRE, and CRL tension testingmachines at a constant time-to-break has been found tominimize differences in test results between the three types oftension testing machines. When ten
38、sile tests are performed at afixed time-to-break, then reasonable agreement in breakingforce has generally been found to exist between CRT and CREtension testing machines.4Consistent results are also obtainedbetween different manufacturers of CRL tension testing ma-chines when they are operated at t
39、he same time-to-break. Theagreement is not necessarily good, however, between CRE orCRT tension testing machines on the one hand and CRLtension testing machines on the other even when they are alloperated at the same time-to-break. The CRE-type tester is thepreferred tension testing machine.5.9.2 Th
40、is test method specifies an average time-to-break of20 6 3 s as recommended by ISO TC 38 on Textiles, TheInternational Standards Association test committee for stan-dardizing tests for fibers, yarns, and fabrics. It also provides foralternate speeds, such as 300 6 10 mm 12 6 0.5 in./minwhen using a
41、250-mm 10-in. gage length. See 9.2.5.9.3 The tolerance of 63 s for the time-to-break is wideenough to permit convenient adjustment of the tension testingmachines rate of operation, and it is narrow enough to ensuregood agreement between tests. The difference in breaking forcebetween tests at 17 and
42、23 s will usually not exceed 1.5 % ofthe higher value.5.9.4 In case a tension testing machine is not capable ofbeing operated at 20-s time-to-break, alternative rates ofoperation are included in this test method. These alternativerates may be used only by agreement between the partiesconcerned or wh
43、en required in an applicable material specifi-cation.5.10 Tests on Wet SpecimensTests on wet specimens areusually made only on yarns which show a loss of breakingforce when wet or when exposed to high humidity, forexample, yarns made from animal fibers and man-made fibersbased on regenerated and mod
44、ified cellulose. Wet tests aremade on flax yarns to detect adulteration by failure to show again in breaking force.5.11 Tests on Oven-Dried Specimens and Specimens at HighTemperaturesTests on oven-dried specimens at standard orhigh temperatures are usually made only on yarns that will beused at high
45、 temperatures or will be used under very dryconditions which will affect the observed breaking force, forexample, on rayon yarns intended for use in tire cords andyarns for other industrial purposes. Note that results obtainedwhen testing oven-dried specimens at standard temperaturewill not necessar
46、ily agree with the results obtained whentesting oven-dried yarns at high temperatures.5.12 Tests on Specimens at Low TemperaturesTests onspecimens exposed to low temperatures are usually made onlyon yarns that will be used at low temperatures, for example,yarns used in outerwear designed for cold cl
47、imates or outer-space situations. Low-temperature tests are made on coatedyarns used in the manufacture of materials used in outdoorapplications, such as screening fabrics.6. Apparatus and Reagents6.1 Tension Testing Machine, of the CRE, CRL, or CRTtype, conforming to Specification D76, with respect
48、 to forceindication, working range, capacity, and verification of re-corded elongation, and designed for operation at the ratesspecified in 9.1. A variable-speed drive, a change of gears, orinterchangeable weights are required to obtain the 20-s time-to-break. If the rate of operation is adjusted in
49、 steps, the stepsshould be no greater than 1.25:1.00. The tension testingmachine may be equipped with: (1) clamps having flat-facedjaws or (2) capstan-, drum-, or snubbing-type clamps (Note 5).Automatic (self-loading and recording) single-end tensiontesting machines may be used, provided they meet the require-ments as to gage length, rate of operation, and accuracy ofcalibration. The tension testing machine may be interfacedwith a computer system for operation and data gathering. TheCRE-type tension testing machine is recommended unlessotherwise agreed upon be
