1、Designation: D695 15Standard Test Method forCompressive Properties of Rigid Plastics1This standard is issued under the fixed designation D695; 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 p
2、arentheses 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 me-chanica
3、l properties of unreinforced and reinforced rigidplastics, including high-modulus composites, when loaded incompression at relatively low uniform rates of straining orloading. Test specimens of standard shape are employed. Thisprocedure is applicable for a composite modulus up to andincluding 41,370
4、 MPa (6,000,000 psi).1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.NOTE 1For compressive properties of resin-matrix composites rein-forced with oriented continuous, discontinuous, or cross-plyreinforcements, tests may be made
5、in accordance with Test MethodD3410/D3410M or D6641/D6641M.1.3 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-bi
6、lity of regulatory limitations prior to use. A specific precau-tionary statement is given in 13.1.NOTE 2This standard is equivalent to ISO 604.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD883 Termino
7、logy Relating to PlasticsD3410/D3410M Test Method for Compressive Properties ofPolymer Matrix Composite Materials with UnsupportedGage Section by Shear LoadingD4000 Classification System for Specifying Plastic Materi-alsD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensD6641/D6641
8、M Test Method for Compressive Properties ofPolymer Matrix Composite Materials Using a CombinedLoading Compression (CLC) Test FixtureE4 Practices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Exten-someter SystemsE691 Practice for Conducting an Interlab
9、oratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:3ISO 604 PlasticsDetermination of Compressive Properties3. Terminology3.1 GeneralThe definitions of plastics used in this testmethod are in accordance with Terminology D883 unlessotherwise indicated.3.2 Definitions:3.2.1 compre
10、ssive 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 test specimen, that is, thechange in length per unit of original
11、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 stress(nominal) carried by the specimen at the moment of rupture
12、.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 original cross section within the gageboundaries, carried by th
13、e 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 almost1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility
14、 of Subcommittee D20.10 on Mechanical Properties.Current edition approved Sept. 1, 2015. Published September 2015. Originallyapproved in 1942. Last previous edition approved in 2010 as D695 - 10. DOI:10.1520/D0695-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AST
15、M Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*A Summary of Cha
16、nges section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1universally used. Under some circumstances the compressiveproperties have been expressed per unit of prevailing crosssection. These proper
17、ties 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 as abscis-sas.3.2.7 compressive yield pointthe first point on the stress-strain diagram at w
18、hich an increase in strain occurs without anincrease in stress.3.2.8 compressive yield 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
19、of failure.3.2.10 modulus of elasticitythe ratio of stress (nominal) tocorresponding 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
20、curve departs from linearity by a specifiedpercent of deformation (offset).3.2.12 percent 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 a
21、ny deviation from propor-tionality of stress to strain (Hookes law). It is expressed inforce per unit area.3.2.14 slenderness ratiothe ratio of the length of a columnof uniform cross section to its least radius of gyration. Forspecimens of uniform rectangular cross section, the radius ofgyration is
22、0.289 times the smaller cross-sectional dimension.For specimens of uniform circular cross section, the radius ofgyration is 0.250 times the diameter. For specimens of tubularcross section, the radius of gyration is calculated as follows:Rg5=D21d24(1)where:Rg= radius of gyration,D = outside diameter,
23、 andd = inside 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 modulus of elasticity,yield stress, deformation b
24、eyond 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, the compressive strengthhas a very definite
25、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 materials will continue to deform incompression
26、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-ing data for research and development, quali
27、ty 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 additional testssuch as impact, creep, and fatigue
28、.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 precedence over those mentioned in thistest me
29、thod. If there is no material specification, then thedefault conditions apply. Table 1 in Classification D4000 liststhe ASTM materials standards that currently exist.5. Apparatus5.1 Testing MachineAny suitable testing machine capableof control of constant-rate-of-crosshead movement and com-prising e
30、ssentially 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 IndicatorA load-indicating mechanism ca-pable o
31、f 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). The accuracy of the testing machineshall be
32、 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 record this distance (or any change in it) a
33、s 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 extensometers cited herein apply tocompressomet
34、ers as well.5.3 Compression ToolA compression 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 otherin a plane normal to the vertical loading
35、 axis. Examples ofsuitable compression tools are shown in Fig. 1 and Fig. 2.D695 1525.4 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, thickness, diameter,and length of the sp
36、ecimens.6. Test Specimens6.1 Unless otherwise specified in the materialsspecifications, the specimens described in 6.2 through 6.8 shallbe used. These specimens may be prepared by machiningoperations from materials in sheet, plate, rod, tube, or similarform, or they may be prepared by compression or
37、 injectionmolding of the material to be tested. All machining operationsshall be done carefully so that smooth surfaces result. Greatcare shall be taken in machining the ends so that smooth, flatparallel surfaces and sharp, clean edges, to within 0.025 mm(0.001 in.) perpendicular to the long axis of
38、 the specimen,result.6.2 The standard test specimen for strength measurements,except as indicated in 6.3 6.8, shall be in the form of a rightcylinder or prism whose length is twice its principal width ordiameter. Preferred specimen sizes are 12.7 by 12.7 by 25.4mm (0.50 by 0.50 by 1 in.) (prism), or
39、 12.7 mm in diameter by25.4 mm (cylinder). The standard test specimen for modulus oroffset yield measurements shall be of such dimensions that theslenderness ratio is in the range from 11 to 16:1. In this case,preferred specimen sizes are 12.7 by 12.7 by 50.8 mm (0.50 by0.50 by 2 in.) (prism), or 12
40、.7 mm in diameter by 50.8 mm(cylinder).6.2.1 When the standard specimens (right cylinders orprisms) cannot be obtained due to the thinness of the material(typically less than 6.4 mm (0.25 in.), alternative specimensoutlined in 6.7.1 and 6.7.2 shall be used.6.3 For rod, the test specimen for strength
41、 measurementsshall have a diameter equal to the diameter of the rod and alength twice the diameter of the rod. The test specimen formodulus or offset yield measurements shall have a diameterequal to the diameter of the rod and a length such thatslenderness ratio is in the range from 11 to 16:1. If t
42、he diameterof the rod is too large to obtain failure due to limitations of thetest equipment, specimens outlined in 6.2 shall be machinedfrom the center of the rod.6.4 For tubes, the test specimen for strength measurementsshall have a diameter equal to the diameter of the tube and alength of 25.4 mm
43、 (1 in.). This specimen shall be used for tubeswith a wall thickness of 1 mm (0.039 in.) or over, to insidediameters of 6.4 mm (0.25 in.) or over, and to outsidediameters of 50.8 mm (2.0 in.) or less. If the diameter of thetube is too large to obtain failure due to limitations of the testequipment,
44、specimens outlined in 6.2 shall be machined fromthe wall of the tube. For crushing-load determinations (at rightNOTE 1Devices similar to the one illustrated have been successfullyused in a number of different laboratories. Details of the device developedat the National Institute for Standards and Te
45、chnology 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 Thin SpecimenD695 153angles to the longitu
46、dinal axis), the specimen size shall be thesame, with the diameter becoming the height. The test speci-men for modulus or offset yield measurements shall have adiameter equal to the diameter of the tube and a length suchthat the slenderness ratio is in the range from 11 to 16:1.6.5 Where it is desir
47、ed 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 12.7 mm square, witha sufficient number of layers to produce a height of approxi-mately 25.4 mm (actual height achievable will be dependentupon individual lay
48、er thickness), shall be used for strengthmeasurements. The test specimen for modulus or offset yieldmeasurements shall consist of a pile-up of 12.7 mm squaresheets to produce a height such that slenderness ratio is in therange from 11 to 16:1.6.6 When testing material that may be suspected ofanisotr
49、opy, duplicate sets of test specimens shall be preparedhaving their long axis respectively parallel with and normal tothe suspected direction of anisotropy.6.7 Reinforced Plastics, including High-Strength Compos-ites and Highly Orthotropic LaminatesThe following speci-mens shall be used for reinforced materials.6.7.1 For materials 3.2 mm to 6.4 mm (0.125 in. to 0.25 in.),the specimen used for strength measurements shall consist of aprism having a cross section of 12.7 mm (0.5 in.) by thethickness of the material and a length of 12.7 mm (0.5 in).(Spe
