1、Designation: D638 14Standard Test Method forTensile Properties of Plastics1This standard is issued under the fixed designation D638; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses
2、 indicates the year of last reapproval. Asuperscript 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. Scope*1.1 This test method covers the determination of the tensileproperties of
3、 unreinforced and reinforced plastics in the formof standard dumbbell-shaped test specimens when tested underdefined conditions of pretreatment, temperature, humidity, andtesting machine speed.1.2 This test method is applicable for testing materials ofany thickness up to 14 mm (0.55 in.). However, f
4、or testingspecimens in the form of thin sheeting, including film less than1.0 mm (0.04 in.) in thickness, ASTM standard D882 is thepreferred test method. Materials with a thickness greater than14 mm (0.55 in.) shall be reduced by machining.1.3 This test method includes the option of determiningPoiss
5、ons ratio at room temperature.NOTE 1This standard and ISO 527-1 address the same subject matter,but differ in technical content.NOTE 2This test method is not intended to cover precise physicalprocedures. It is recognized that the constant rate of crosshead movementtype of test leaves much to be desi
6、red from a theoretical standpoint, thatwide differences may exist between rate of crosshead movement and rateof strain between gage marks on the specimen, and that the testing speedsspecified disguise important effects characteristic of materials in theplastic state. Further, it is realized that var
7、iations in the thicknesses of testspecimens, which are permitted by these procedures, produce variations inthe surface-volume ratios of such specimens, and that these variations mayinfluence the test results. Hence, where directly comparable results aredesired, all samples should be of equal thickne
8、ss. Special additional testsshould be used where more precise physical data are needed.NOTE 3This test method may be used for testing phenolic moldedresin or laminated materials. However, where these materials are used aselectrical insulation, such materials should be tested in accordance withTest M
9、ethods D229 and Test Method D651.NOTE 4For tensile properties of resin-matrix composites reinforcedwith oriented continuous or discontinuous high modulus 20-GPa(3.0 106-psi) fibers, tests shall be made in accordance with TestMethod D3039/D3039M.1.4 Test data obtained by this test method have been fo
10、undto be useful in engineering design. However, it is important toconsider the precautions and limitations of this method foundin Note 2 and Section 4 before considering these data forengineering design.1.5 The values stated in SI units are to be regarded asstandard. The values given in parentheses
11、are for informationonly.1.6 This standard does not purport to address 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 prio
12、r to use.2. Referenced Documents2.1 ASTM Standards:2D229 Test Methods for Rigid Sheet and Plate MaterialsUsed for Electrical InsulationD412 Test Methods for Vulcanized Rubber and Thermoplas-tic ElastomersTensionD618 Practice for Conditioning Plastics for TestingD651 Test Method for Test for Tensile
13、Strength of MoldedElectrical Insulating Materials (Withdrawn 1989)3D882 Test Method for Tensile Properties of Thin PlasticSheetingD883 Terminology Relating to PlasticsD1822 Test Method for Tensile-Impact Energy to BreakPlastics and Electrical Insulating MaterialsD3039/D3039M Test Method for Tensile
14、Properties of Poly-mer Matrix Composite MaterialsD4000 Classification System for Specifying Plastic Materi-alsD4066 Classification System for Nylon Injection and Extru-sion Materials (PA)D5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE4 Practices for Force Verification of Testi
15、ng Machines1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved Dec. 15, 2014. Published March 2015. Originallyapproved in 1941. Last previous edition approved in 2010 as
16、D638 - 10. DOI:10.1520/D0638-14.2For 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.3The last approved version of
17、 this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E83 Practice for Verification and Classification of Exten-someter
18、SystemsE132 Test Method for Poissons Ratio at Room TemperatureE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:4ISO 527-1 Determination of Tensile Properties3. Terminology3.1 DefinitionsDefinitions of terms applying to this testmethod a
19、ppear in Terminology D883 and Annex A2.4. Significance and Use4.1 This test method is designed to produce tensile propertydata for the control and specification of plastic materials. Thesedata are also useful for qualitative characterization and forresearch and development.4.2 Some material specific
20、ations that require the use of thistest method, but with some procedural modifications that takeprecedence when adhering to the specification. Therefore, it isadvisable to refer to that material specification before using thistest method. Table 1 in Classification D4000 lists the ASTMmaterials stand
21、ards that currently exist.4.3 Tensile properties are known to vary with specimenpreparation and with speed and environment of testing.Consequently, where precise comparative results are desired,these factors must be carefully controlled.4.4 It is realized that a material cannot be tested without als
22、otesting the method of preparation of that material. Hence, whencomparative tests of materials per se are desired, exercise greatcare to ensure that all samples are prepared in exactly the sameway, unless the test is to include the effects of samplepreparation. Similarly, for referee purposes or com
23、parisonswithin any given series of specimens, care shall be taken tosecure the maximum degree of uniformity in details ofpreparation, treatment, and handling.4.5 Tensile properties provide useful data for plastics engi-neering design purposes. However, because of the high degreeof sensitivity exhibi
24、ted by many plastics to rate of straining andenvironmental conditions, data obtained by this test methodcannot be considered valid for applications involving load-timescales or environments widely different from those of this testmethod. In cases of such dissimilarity, no reliable estimation ofthe l
25、imit of usefulness can be made for most plastics. Thissensitivity to rate of straining and environment necessitatestesting over a broad load-time scale (including impact andcreep) and range of environmental conditions if tensile prop-erties are to suffice for engineering design purposes.NOTE 5Since
26、the existence of a true elastic limit in plastics (as inmany other organic materials and in many metals) is debatable, thepropriety of applying the term “elastic modulus” in its quoted, generallyaccepted definition to describe the “stiffness” or “rigidity” of a plastic hasbeen seriously questioned.
27、The exact stress-strain characteristics of plasticmaterials are highly dependent on such factors as rate of application ofstress, temperature, previous history of specimen, etc. However, stress-strain curves for plastics, determined as described in this test method,almost always show a linear region
28、 at low stresses, and a straight linedrawn tangent to this portion of the curve permits calculation of an elasticmodulus of the usually defined type. Such a constant is useful if itsarbitrary nature and dependence on time, temperature, and similar factorsare realized.5. Apparatus5.1 Testing MachineA
29、 testing machine of the constant-rate-of-crosshead-movement type and comprising essentiallythe following:5.1.1 Fixed MemberA fixed or essentially stationarymember carrying one grip.5.1.2 Movable MemberA movable member carrying asecond grip.5.1.3 GripsGrips for holding the test specimen betweenthe fi
30、xed member and the movable member of the testingmachine can be either the fixed or self-aligning type.5.1.3.1 Fixed grips are rigidly attached to the fixed andmovable members of the testing machine. When this type ofgrip is used take extreme care to ensure that the test specimenis inserted and clamp
31、ed so that the long axis of the testspecimen coincides with the direction of pull through thecenter line of the grip assembly.5.1.3.2 Self-aligning grips are attached to the fixed andmovable members of the testing machine in such a manner thatthey will move freely into alignment as soon as any load
32、isapplied so that the long axis of the test specimen will coincidewith the direction of the applied pull through the center line ofthe grip assembly. Align the specimens as perfectly as possiblewith the direction of pull so that no rotary motion that mayinduce slippage will occur in the grips; there
33、 is a limit to theamount of misalignment self-aligning grips will accommodate.5.1.3.3 The test specimen shall be held in such a way thatslippage relative to the grips is prevented insofar as possible.Grip surfaces that are deeply scored or serrated with a patternsimilar to those of a coarse single-c
34、ut file, serrations about 2.4mm (0.09 in.) apart and about 1.6 mm (0.06 in.) deep, havebeen found satisfactory for most thermoplastics. Finer serra-tions have been found to be more satisfactory for harderplastics, such as the thermosetting materials. It is important thatthe serrations be kept clean
35、and sharp. Should breaking in thegrips occur, even when deep serrations or abraded specimensurfaces are used, other techniques shall be used. Othertechniques that have been found useful, particularly withsmooth-faced grips, are abrading that portion of the surface ofthe specimen that will be in the
36、grips, and interposing thinpieces of abrasive cloth, abrasive paper, or plastic, or rubber-coated fabric, commonly called hospital sheeting, between thespecimen and the grip surface. No. 80 double-sided abrasivepaper has been found effective in many cases. An open-meshfabric, in which the threads ar
37、e coated with abrasive, has alsobeen effective. Reducing the cross-sectional area of the speci-men may also be effective. The use of special types of grips issometimes necessary to eliminate slippage and breakage in thegrips.5.1.4 Drive MechanismA drive mechanism for impartinga uniform, controlled v
38、elocity to the movable member with4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.D638 142respect to the stationary member. This velocity is to beregulated as specified in Section 8.5.1.5 Load IndicatorA suitable load-ind
39、icating mecha-nism capable of showing the total tensile load carried by thetest specimen when held by the grips. This mechanism shall beessentially free of inertia lag at the specified rate of testing andshall indicate the load with an accuracy of 61 % of theindicated value, or better. The accuracy
40、of the testing machineshall be verified in accordance with Practices E4.NOTE 6Experience has shown that many testing machines now in useare incapable of maintaining accuracy for as long as the periods betweeninspection recommended in Practices E4. Hence, it is recommended thateach machine be studied
41、 individually and verified as often as may befound necessary. It frequently will be necessary to perform this functiondaily.5.1.6 The fixed member, movable member, drivemechanism, and grips shall be constructed of such materialsand in such proportions that the total elastic longitudinal strainof the
42、 system constituted by these parts does not exceed 1 % ofthe total longitudinal strain between the two gage marks on thetest specimen at any time during the test and at any load up tothe rated capacity of the machine.5.1.7 Crosshead Extension IndicatorA suitable extensionindicating mechanism capable
43、 of showing the amount ofchange in the separation of the grips, that is, crossheadmovement. This mechanism shall be essentially free of inertiallag at the specified rate of testing and shall indicate thecrosshead movement with an accuracy of 610 % of theindicated value.5.2 Extension Indicator (exten
44、someter)A suitable instru-ment shall be used for determining the distance between twodesignated points within the gauge length of the test specimenas the specimen is stretched. For referee purposes, the exten-someter must be set at the full gage length of the specimen, asshown in Fig. 1. It is desir
45、able, but not essential, that thisinstrument automatically record this distance, or any change init, as a function of the load on the test specimen or of theelapsed time from the start of the test, or both. If only the latteris obtained, load-time data must also be taken. This instrumentshall be ess
46、entially free of inertia at the specified speed oftesting. Extensometers shall be classified and their calibrationperiodically verified in accordance with Practice E83.5.2.1 Modulus-of-Elasticity MeasurementsFor modulus-of-elasticity measurements, an extensometer with a maximumstrain error of 0.0002
47、 mm/mm (in./in.) that automatically andcontinuously records shall be used. An extensometer classifiedby Practice E83 as fulfilling the requirements of a B-2classification within the range of use for modulus measure-ments meets this requirement.5.2.2 Low-Extension MeasurementsFor elongation-at-yield
48、and low-extension measurements (nominally 20 % orless), the same above extensometer, attenuated to 20 %extension, is acceptable. In any case, the extensometer systemmust meet at least Class C (Practice E83) requirements, whichinclude a fixed strain error of 0.001 strain or 61.0 % of theindicated str
49、ain, whichever is greater.5.2.3 High-Extension MeasurementsFor making measure-ments at elongations greater than 20 %, measuring techniqueswith error no greater than 610 % of the measured value areacceptable.5.3 MicrometersApparatus for measuring the width andthickness of the test specimen shall comply with the require-ments of Test Method D5947.6. Test Specimens6.1 Sheet, Plate, and Molded Plastics:6.1.1 Rigid and Semirigid PlasticsThe test specimen shallconform to the dimensions shown in Fig. 1. The Type Ispecimen is the preferred specimen and shall be used
