ASTM D695-2002a Standard Test Method for Compressive Properties of Rigid Plastics《硬质塑料抗压特性的标准试验方法》.pdf

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1、Designation: D 695 02aStandard Test Method forCompressive Properties of Rigid Plastics1This standard is issued under the fixed designation D 695; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i

2、n parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the determination of the me-chanical

3、 properties of unreinforced and reinforced rigid plas-tics, including high-modulus composites, when loaded incompression at relatively low uniform rates of straining orloading. Test specimens of standard shape are employed.1.2 The values stated in SI units are to be regarded as thestandard. The valu

4、es in parentheses are for information only.NOTE 1For compressive properties of resin-matrix composites rein-forced with oriented continuous, discontinuous, or cross-ply reinforce-ments, tests may be made in accordance with Test Method D 3410.1.3 This standard does not purport to address all of thesa

5、fety 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. A specific precau-tionary statement is given in Note 11.NOTE 2This test

6、method is technically equivalent to ISO 604.2. Referenced Documents2.1 ASTM Standards:D 618 Practice for Conditioning Plastics for Testing2D 638 Test Method for Tensile Properties of Plastics2D 883 Terminology Relating to Plastics2D 3410 Test Method for Compressive Properties of Poly-mer Matrix Comp

7、osite Materials with Unsupported GageSection by Shear Loading3D 4000 Classification System for Specifying Plastic Mate-rials4D 4066 Classification System for Nylon Injection and Ex-trusion Materials4D 5947 Test Methods for Physical Dimensions of SolidPlastics Specimens5E4 Practices for Force Verific

8、ation of Testing Machines6E83 Practice for Verification and Classification of Exten-someters6E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method73. Terminology3.1 General The definitions of plastics used in this testmethod are in accordance with Terminol

9、ogy D 883 unlessotherwise indicated.3.2 Definitions:3.2.1 compressive deformationthe decrease in length pro-duced in the gage length of the test specimen by a compressiveload. It is expressed in units of length.3.2.2 compressive strainthe ratio of compressive defor-mation to the gage length of the t

10、est specimen, that is, thechange in length per unit of original length along the longitu-dinal axis. It is expressed as a dimensionless ratio.3.2.3 compressive strengththe maximum compressivestress (nominal) carried by a test specimen during a compres-sion test. It may or may not be the compressive

11、stress(nominal) carried by the specimen at the moment of rupture.3.2.4 compressive strength at failure (nominal)the com-pressive stress (nominal) sustained at the moment of failure ofthe test specimen if shattering occurs.3.2.5 compressive stress (nominal)the compressive loadper unit area of minimum

12、 original cross section within the gageboundaries, carried by the test specimen at any given moment.It is expressed in force per unit area.3.2.5.1 DiscussionThe expression of compressive proper-ties in terms of the minimum original cross section is almostuniversally used. Under some circumstances th

13、e compressiveproperties have been expressed per unit of prevailing crosssection. These properties are called “true” compressive prop-erties.3.2.6 compressive stress-strain diagrama diagram inwhich values of compressive stress are plotted as ordinatesagainst corresponding values of compressive strain

14、 as abscis-sas.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved August 10, 2002. Published October 2002. Originallypublished as D 695 42 T. Last previous edition D 69

15、5 02.2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 15.03.4Annual Book of ASTM Standards, Vol 08.02.5Annual Book of ASTM Standards, Vol 08.03.6Annual Book of ASTM Standards, Vol 03.01.7Annual Book of ASTM Standards, Vol 14.02.1*A Summary of Changes section appears at t

16、he end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.7 compressive yield pointthe first point on the stress-strain diagram at which an increase in strain occurs without anincrease in stress.3.2.8 compressive yie

17、ld strengthnormally the stress at theyield point (see also section 3.2.11).3.2.9 crushing loadthe maximum compressive force ap-plied to the specimen, under the conditions of testing, thatproduces a designated degree of failure.3.2.10 modulus of elasticitythe ratio of stress (nominal) tocorresponding

18、 strain below the proportional limit of a material.It is expressed in force per unit area based on the average initialcross-sectional area.3.2.11 offset compressive yield strengththe stress at whichthe stress-strain curve departs from linearity by a specifiedpercent of deformation (offset).3.2.12 pe

19、rcent compressive strainthe compressive defor-mation of a test specimen expressed as a percent of the originalgage length.3.2.13 proportional limitthe greatest stress that a materialis capable of sustaining without any deviation from propor-tionality of stress to strain (Hookes law). It is expressed

20、 inforce per unit area.3.2.14 slenderness ratiothe ratio of the length of a col-umn of uniform cross section to its least radius of gyration. Forspecimens of uniform rectangular cross section, the radius ofgyration is 0.289 times the smaller cross-sectional dimension.For specimens of uniform circula

21、r cross section, the radius ofgyration is 0.250 times the diameter.4. Significance and Use4.1 Compression tests provide information about the com-pressive properties of plastics when employed under conditionsapproximating those under which the tests are made.4.2 Compressive properties include modulu

22、s of elasticity,yield stress, deformation beyond yield point, and compressivestrength (unless the material merely flattens but does notfracture). Materials possessing a low order of ductility may notexhibit a yield point. In the case of a material that fails incompression by a shattering fracture, t

23、he compressive strengthhas a very definite value. In the case of a material that does notfail in compression by a shattering fracture, the compressivestrength is an arbitrary one depending upon the degree ofdistortion that is regarded as indicating complete failure of thematerial. Many plastic mater

24、ials will continue to deform incompression until a flat disk is produced, the compressivestress (nominal) rising steadily in the process, without anywell-defined fracture occurring. Compressive strength canhave no real meaning in such cases.4.3 Compression tests provide a standard method of obtain-i

25、ng data for research and development, quality control, accep-tance or rejection under specifications, and special purposes.The tests cannot be considered significant for engineeringdesign in applications differing widely from the load-time scaleof the standard test. Such applications require additio

26、nal testssuch as impact, creep, and fatigue.4.4 Before proceeding with this test method, referenceshould be made to the ASTM specification for the materialbeing tested. Any test specimen preparation, conditioning,dimensions, and testing parameters covered in the materialsspecification shall take pre

27、cedence over those mentioned in thistest method. If there is no material specification, then thedefault conditions apply. Table 1 in Classification D 4000 liststhe ASTM materials standards that currently exist.5. Apparatus5.1 Testing MachineAny suitable testing machine capableof control of constant-

28、rate-of-crosshead movement and com-prising essentially the following:5.1.1 Drive MechanismA drive mechanism for impartingto the movable cross-head member, a uniform, controlledvelocity with respect to the base (fixed member), with thisvelocity to be regulated as specified in Section 9.5.1.2 Load Ind

29、icatorA load-indicating mechanism ca-pable of showing the total compressive load carried by the testspecimen. The mechanism shall be essentially free frominertia-lag at the specified rate of testing and shall indicate theload with an accuracy of 61 % of the maximum indicatedvalue of the test (load).

30、 The accuracy of the testing machineshall be verified at least once a year in accordance withPractices E4.5.2 CompressometerA suitable instrument for determin-ing the distance between two fixed points on the test specimenat any time during the test. It is desirable that this instrumentautomatically

31、record this distance (or any change in it) as afunction of the load on the test specimen. The instrument shallbe essentially free of inertia-lag at the specified rate of loadingand shall conform to the requirements for a Class B-2extensometer as defined in Practice E83.NOTE 3The requirements for ext

32、ensometers cited herein apply tocompressometers as well.5.3 Compression ToolAcompression tool for applying theload to the test specimen. This tool shall be so constructed thatloading is axial within 1:1000 and applied through surfaces thatare flat within 0.025 mm (0.001 in.) and parallel to each oth

33、erin a plane normal to the vertical loading axis. Examples ofsuitable compression tools are shown in Fig. 1 and Fig. 2.5.4 Supporting JigA supporting jig for thin specimens isshown in Fig. 3 and Fig. 4.5.5 MicrometersSuitable micrometers, reading to 0.01mm or 0.001 in. for measuring the width, thick

34、ness, and lengthof the specimens.6. Test Specimens6.1 Unless otherwise specified in the materials specifica-tions, the specimens described in 6.2 and 6.7 shall be used.These specimens may be prepared by machining operationsfrom materials in sheet, plate, rod, tube, or similar form, orthey may be pre

35、pared by compression or injection molding ofthe material to be tested. All machining operations shall bedone carefully so that smooth surfaces result. Great care shallbe taken in machining the ends so that smooth, flat parallelsurfaces and sharp, clean edges, to within 0.025 mm (0.001 in.)perpendicu

36、lar to the long axis of the specimen, result.6.2 The standard test specimen, except as indicated in6.3-6.7, shall be in the form of a right cylinder or prism whoselength is twice its principal width or diameter. Preferredspecimen sizes are 12.7 by 12.7 by 25.4 mm (0.50 by 0.50 byD 695 02a21 in.) (pr

37、ism), or 12.7 mm in diameter by 25.4 mm (cylinder).Where elastic modulus and offset yield-stress data are desired,the test specimen shall be of such dimensions that the slender-ness ratio is in the range from 11 to 16:1. In this case, preferredspecimen sizes are 12.7 by 12.7 by 50.8 mm (0.50 by 0.50

38、 by2 in.) (prism), or 12.7 mm in diameter by 50.8 mm (cylinder).6.3 For rod material, the test specimen shall have a diameterequal to the diameter of the rod and a sufficient length to allowa specimen slenderness ratio in the range from 11 to 16:1.6.4 When testing tubes, the test specimen shall have

39、 adiameter equal to the diameter of the tube and a length of 25.4mm (1 in.) (Note 4). For crushing-load determinations (at rightangles to the longitudinal axis), the specimen size shall be thesame, with the diameter becoming the height.NOTE 4This specimen can be used for tubes with a wall thickness

40、of1 mm (0.039 in.) or over, to inside diameters of 6.4 mm (0.25 in.) or over,and to outside diameters of 50.8 mm (2.0 in.) or less.6.5 Where it is desired to test conventional high-pressurelaminates in the form of sheets, the thickness of which is lessthan 25.4 mm (1 in.), a pile-up of sheets 25.4 m

41、m square, witha sufficient number of layers to produce a height of at least 25.4mm, may be used.6.6 When testing material that may be suspected of anisot-ropy, duplicate sets of test specimens shall be prepared havingtheir long axis respectively parallel with and normal to thesuspected direction of

42、anisotropy.6.7 Reinforced Plastics, Including High-Strength Compos-ites and High-Strength Composites and Highly OrthotropicLaminatesThe following specimens shall be used for rein-forced materials, or for other materials when necessary tocomply with the slenderness ratio requirements or to permitatta

43、chment of a deformation-measuring device.6.7.1 For materials 3.2 mm (18 in.) and over in thickness, aspecimen shall consist of a prism having a cross section of 12.7mm (12 in.) by the thickness of the material and a length suchthat the slenderness ratio is in the range from 11 to 16:1 (Note5).6.7.2

44、For materials under 3.2 mm (18 in.) thick, or whereelastic modulus testing is required and the slenderness ratiodoes not provide for enough length for attachment of acompressometer or similar device, a specimen conforming tothat shown in Fig. 5 shall be used. The supporting jig shown inFig. 3 and Fi

45、g. 4 shall be used to support the specimen duringtesting (Note 6).NOTE 5If failure for materials in the thickness range of 3.2 mm (18in.) is by delamination rather than by the desirable shear plane fracture, thematerial may be tested in accordance with 6.7.2.NOTE 6Round-robin tests have established

46、that relatively satisfactorymeasurements of modulus of elasticity may be obtained by applying acompressometer to the edges of the jig-supported specimen.NOTE 1Devices similar to the one illustrated have been successfullyused in a number of different laboratories. Details of the device developedat th

47、e National Institute for Standards and Technology are given in thepaper byAitchinson, C. S., and Miller, J.A., “ASubpress for CompressiveTests,” NationalAdvisory Committee forAeronautics, Technical Note No.912, 1943.FIG. 1 Subpress for Compression TestsFIG. 2 Compression ToolFIG. 3 Support Jig for T

48、hin SpecimenD 695 02a36.8 When testing syntactic foam, the standard test specimenshall be in the form of a right cylinder 25.4 mm (1 in.) indiameter by 50.8 mm (2 in.) in length.7. Conditioning7.1 ConditioningCondition the test specimens at 23 62C (73.4 6 3.6F) and 50 6 5 % relative humidity for not

49、 lessthan 40 h prior to test in accordance with Procedure A ofPractice D 618 unless otherwise specified by contract orrelevant ASTM material specification. Reference pre-test con-ditioning, to settle disagreements, shall apply tolerances of61C (1.8F) and 62 % relative humidity.7.1.1 Note that for some hygroscopic materials, such asnylons, the material specifications (for example, ClassificationSystem D 4066) call for testing “dry as-molded specimens.”Such requirements take precedence over the above routinepreconditioning to 50 % RH and requi