1、Designation: D 953 02Standard Test Method forBearing Strength of Plastics1This standard is issued under the fixed designation D 953; 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 (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. Scope1.1 This test method covers the determination of the bearingstrength of rigid
3、plastics in either sheet or molded form.Procedure A is applicable for tension loading and Procedure Bfor compression loading.1.2 Test data obtained by this test method is relevant andappropriate for use in engineering design.1.3 The values stated in SI units are to be regarded as thestandard. The va
4、lues given in parentheses are for informationonly.1.4 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 r
5、egulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:D 618 Practice for Conditioning Plastics for Testing2D 883 Terminology Relating to Plastics2D 4000 Classification System for Specifying Plastic Mate-rials3D 4066 Class
6、ification System for Nylon Injection and Ex-trusion Materials3D 4805 Terminology of Plastics Standards4E 4 Practices for Force Verification of Testing Machines5E 6 Terminology Relating to Methods of Mechanical Test-ing53. Terminology3.1 DefinitionsFor definitions of technical terms pertain-ing to pl
7、astics used in this test method, see Terminology D 883or Terminology D 4805.3.2 Definitions of Terms Specific to This Standard:63.2.1 bearing areathe diameter of the hole multiplied bythe thickness of the specimen.3.2.2 bearing strengththe bearing stress at which thebearing hole is deformed 4 % of i
8、ts diameter.3.2.3 bearing stressthe applied load in newtons (orpounds-force) divided by the bearing area in mm2(or in2).3.2.4 edge distance ratiothe distance from the center ofthe bearing hole to the edge of the specimen in the direction ofthe principal stress, divided by the diameter of the hole.3.
9、2.5 maximum bearing stressthe maximum load in new-tons (or pounds-force) sustained by the specimen, divided bythe bearing area.4. Significance and Use4.1 This bearing strength test for plastics is intended toapply in the specification of various thermoplastic or thermo-setting products in sheet form
10、 where rivets, bolts, or similarfastenings are to be used in joining members or sections. It alsois intended to apply wherever sheet materials of the classesindicated are required to sustain edgewise loads that areapplied by means of pins or rods of circular cross section whichpierce the sheet perpe
11、ndicular to the surface.4.2 The purpose of the test is to determine the bearingstrength of the material and to show the bearing stress versusthe deformation of the hole. The allowable deformation of thehole in the material should be such as to produce no loosenessof joints.4.3 While it is a known fa
12、ct that higher strength materialswill generally give higher bearing strengths, there is nosatisfactory method by which bearing strength may be esti-mated from tensile or compressive properties of the material.4.4 Before proceeding with this test method, referenceshould be made to the specification o
13、f the material being tested.Any test specimen preparation, conditioning, dimensions ortesting parameters or combination thereof covered in therelevant ASTM materials specification shall take precedenceover those in this test method. If there are no relevant ASTMmaterial specifications then the defau
14、lt conditions apply.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 April 10, 2002. Published June 2002. Originallypublished as D 953 48 T. Last previous edition D 9
15、53 95.2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 08.02.4Annual Book of ASTM Standards, Vol 08.03.5Annual Book of ASTM Standards, Vol 03.01.6Attention is also directed to Terminology E 6.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
16、ocken, PA 19428-2959, United States.5. Apparatus5.1 Testing MachineA properly calibrated universal test-ing machine that can be operated at a speed of 1.3 6 0.3 mm(0.05 6 0.01 in.)/min, except that in cases of certain types ofmaterial it may be necessary to operate at a slower speed. Thepercentage o
17、f error of the testing machine shall be no morethan 61 % of the applied load as determined in accordancewith Practices E 4.5.2 Tension Loading FixtureA three-plate fixture of hard-ened steel similar to that shown in Fig. 1.5.3 Extension IndicatorA suitable instrument reading in0.0025 mm (0.0001 in.)
18、 for indicating the movement of the freeend of the specimen with relation to the bearing pin in thetension loading fixture. A dial gage fitted with accessories forthis purpose is shown in Fig. 2.5.4 Compression Loading FixtureA type of support with asuitable bearing pin similar to Fig. 3.5.5 Compres
19、sion IndicatorA suitable instrument readingto 0.0025 mm (0.0001 in.) for indicating the movement of thefree end of the specimen with relation to the bearing pin in thecompression loading fixture. A suggested dial gage assemblyfor this purpose is shown in Fig. 4.6. Test Specimens6.1 The test specimen
20、s shall conform to the dimensionsshown in Fig. 5. A size of test specimen shall be chosen thatmost nearly conforms to production requirements of thematerial and the type of loading under consideration. Thethicker specimens with the larger bearing hole are likely to givethe more precise results, alth
21、ough it is advantageous to use thethinner specimens with the smaller bearing hole in testingcertain relatively brittle plastics because they are less likely tofail prematurely. The specimen may be machined from sheet ormolded to finished size. The bearing hole shall be located asshown in Fig. 5. It
22、shall be drilled undersized and reamed tosize as indicated. The hole shall be clean and smooth withsharp edges but not polished. It is suggested that the reamingoperation be done in the drill press by hand without the use ofa jig.7. Number of Test Specimens7.1 At least five specimens shall be tested
23、 for each sample inthe case of isotropic materials.7.2 Ten specimens, five perpendicular to and five parallelwith the principal axis of anisotropy, shall be tested for eachsample in case of anisotropic materials.1Hardened spacer plate.26.3-mm (-in.) steel bolts in reamed holes.3Hardened side plate.4
24、Extensometer span.5Hardened steel pin in reamed hole.6Test specimen.NoteCritical dimensions are as follows:TypeBearing Hole Diam-eter, mm (in.)Bearing Pin Diameter, mm(in.)Thickness ofSpacer Plate,mmA(in.)I 3.175 + 0.025 3.150 + 0.000 3.2 0.000 0.025(0.125 + 0.0010 (0.124 + 0.0000 (18) 0.0000) 0.001
25、0)II 6.350 + 0.025 6.325 + 0.000 6.3 0.000 0.025(0.250 + 0.0010 (0.249 + 0.0000 (14) 0.0000) 0.0010)AThe spacer plate shall be shimmed to a thickness of 0.025 to 0.125 mm (0.001to 0.005 in.) greater than the specimen under test.FIG. 1 Steel Tension Loading Fixture1Spacer plate.2Dial gage.3Double foo
26、t ring mounted on spindle of dial gage.4Bearing pin.5Yoke mounted on specimen.6Test specimen.7Plan view of yoke.FIG. 2 Tension Loading AssemblyD9530227.3 Specimens that break at some obvious flaw shall bediscarded and retests made, unless such flaws constitute avariable the effect of which is being
27、studied.8. Conditioning8.1 ConditioningCondition the test specimens at 23 62C (73.4 6 3.6F) and 50 6 5 % relative humidity for not lessthan 40 h prior to test in accordance with Procedure A ofPractice D 618, unless otherwise specified by contract or therelevant ASTM material specification. Reference
28、 pre-test con-ditioning, to settle disagreements, shall apply tolerances of61C (1.8F) and 62 % relative humidity.8.2 Test ConditionsConduct tests at 23 6 2C (73.4 63.6F) and 50 6 5 % relative humidity, unless otherwisespecified by contract or the relevant ASTM material specifica-tion. Reference test
29、ing conditions, to settle disagreements,shall apply tolerances of 61C (1.8F) and 62 % relativehumidity.9. Measurement of Dimensions9.1 Measure the width and thickness of the conditioned testspecimen to the nearest 0.025 mm (0.001 in.) at the bearinghole. Also measure the diameter of the bearing hole
30、 and thedistance from the center of the bearing hole to the edge of thespecimen in the direction of the principal stress to the nearest0.025 mm (0.001 in.).10. Speed of Testing10.1 The mean rate of crosshead travel in the testing ofspecimens shall not exceed 1.3 6 0.3 mm (0.05 6 0.01in.)/min. In any
31、 case the crosshead movement shall be slowenough so that deflection gage readings can be made accu-rately.11. Procedure11.1 The choice of either Procedure A for tension loading(11.2) or Procedure B for compression loading (11.3) isoptional, but it should be recognized that Procedure B giveshigher be
32、aring strength values than Procedure A on the samematerial. Test specimens according to both Procedures A and Bif a complete specification of bearing strength is required.11.2 Procedure A for Tension LoadingMount the speci-men to be tested in the tension loading fixture and attach adeformation indic
33、ator. If a dial gage (Fig. 2) is used, adjust theyoke so that contact is made with the specimen at the levelindicated in Fig. 1. Exception is taken in the case of thosethermoplastic materials which exhibit extended plastic flow.Such specimens tend to “neck down” in the region of thebearing hole, and
34、 it is necessary to mount the yoke 12.7 mm(12in.) below the normal position indicated in A, Fig. 1, so thatit will not slip during test.11.3 Procedure B for Compression LoadingMount thespecimen to be tested in the compression loading fixture andload through a flat, hardened compression plate. Adjust
35、 theclearance between the thrust bushings of the loading fixturesuch that their contact with the specimen is sufficient to supportit in a vertical position without binding. Clamp the hardwoodcheek blocks in place and attach the deformation indicator (seeFig. 4).11.4 Details Common to Procedures A an
36、d BTake care inaligning the long axis of the specimen with the center line ofthe testing fixture. Load the specimen at the prescribed rate ofcrosshead travel and take deformation readings. In case auto-graphic recording is not available, record the load sustained bythe specimen for every 0.0127-mm (
37、0.0005-in.) deformationup to a total deformation of 4 % of the bearing hole diameter.Continue the test until maximum load is sustained and thecorresponding deformation of the bearing hole is recorded.12. Calculation12.1 Plot the load - deflection curve for each specimen.12.2 Use a template, as descr
38、ibed in the Appendix, todetermine the load at 4 % hole deformation.12.3 Calculate the bearing strength as follows:Sb5 P/td! (1)where:Sb= bearing strength, MPa (or psi),P = bearing load at 4 % hole deformation, N (or lbf),d = bearing hole diameter, mm (or in.), andt = specimen thickness, mm (or in.).
39、12.4 Calculate the arithmetic mean of the observations andreport the result to three significant figures.12.5 Calculate the standard deviation of each set of obser-vations and record to two significant figures.13. Report13.1 Report the following information:13.1.1 Complete identification of the mate
40、rial tested, includ-ing type, source, manufacturers code number, form, principaldimensions, and previous history,13.1.2 Direction of cutting and loading specimens,1Test specimen.2Hardened steel pin.3Hardened thrust bushing.NoteCritical dimensions are as follows:TypeBearing Hole Diam-eter,mm (in.)Bea
41、ring Pin Diameter,mm (in.)MinimumClear-ance Be-tweenBushings,mm (in.)I 3.175 + 0.025 3.150 + 0.000 2.8 0.000 0.025(0.125 + 0.0010 (0.124 + 0.0000 (7/64) 0.0000) 0.0010)II 6.350 + 0.025 6.325 + 0.000 6.0 0.000 0.025(0.250 + 0.0010 (0.249 + 0.0000 (15/64) 0.0000) 0.0010)FIG. 3 Steel Compression Loadin
42、g FixtureD95302313.1.3 Conditioning procedure and environmental condi-tions under which the tests were conducted,13.1.4 Length, width, and thickness of specimen, in milli-metres (or inches),13.1.5 Diameter of bearing hole, in millimetres (or inches),13.1.6 Edge distance ratio,13.1.7 Mean rate of cro
43、sshead motion in millimetres (orinches) per minute,1Test specimen. 6Dial gage.2Bearing pin. 7Pedestal support.3Thrust bushings. 8Clamp for cheek blocks.4Hanger for dial gage. 9Hard maple cheek blocks to stabilize test specimen.5Spring-supported thrust member of transfer deforma-tion of specimen to d
44、ial gage foot.FIG. 4 Compression Loading AssemblyType Dimensions, mmA(in.) Ream HoleA BCDtoI 11.913 6 0 .127 19.0506 0 .127 120.6 3.2 3.200 6 0 .025(0.469 6 0 .005) (0.750 6 0 .005) (434)(18) (0.126 6 0 .001)II 11.913 6 0 .127 19.050 6 0 .127 120.6 6.4 6.375 6 0 .025(0.469 6 0 .005) (0.750 6 0 .005)
45、 (43414) (0.251 6 0 .001)AAll fractional dimensions shall be held to 60.40 mm (164 in.) tolerance.Edge distance ratio = B/hole diameterFIG. 5 Dimensions of Bearing Strength Test SpecimensD95302413.1.8 Bearing strength in Megapascals (or pounds-forceper square inch), stating whether Procedure A for t
46、ensionloading or Procedure B for compression loading was used,13.1.9 Maximum bearing stress in Megapascals (or pounds-force per square inch), stating whether Procedure A or Proce-dure B was used, and13.1.10 The test method number and published/revisiondate.14. Precision and Bias14.1 Attempts to deve
47、lop a comprehensive interlaboratoryprecision and bias statement for this test method have not beensuccessful because of the small number of laboratories usingthis test method. However, limited precision data from onelaboratory on one material utilizing a single operator, a singleapparatus, on a sing
48、le day and replicate runs of the material hasbeen provided as follows: Determinations were made on twosets of ten individual specimens to provide two test results. Thecoefficient of variation of the two test results averaged 4.9 %with a difference of 0.3 % between results.14.2 There are no recognize
49、d standards to estimate the biasof this test method. Anyone wishing to participate in thedevelopment of precision and bias data should contact thechairman, Subcommittee D20.10 (Section D20.10.01), ASTMInternational, 100 Barr Harbor Drive, West Conshohocken, PA194282959.15. Keywords15.1 bearing strength; compression strength; plasticsAPPENDIX(Nonmandatory Information)X1. DETERMINATION OF BEARING LOADX1.1 Bearing strength has been defined as the bearingstress at which the bearing hole is deformed a
