1、Designation: D953 10Standard Test Method forBearing Strength of Plastics1This standard is issued under the fixed designation D953; 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 i
2、ndicates 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 Department of Defense.1. Scope*1.1 This test method covers the determination of the bearingstrength of rigid pl
3、astics in either sheet form, molded form, orin thermoset pultruded form. Procedure A is applicable fortension loading and Procedure B for 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 b
4、e regarded as thestandard. The values 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
5、determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD5947 Test Methods for Physical Dimensions of
6、 SolidPlastics SpecimensE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Testing3. Terminology3.1 DefinitionsFor definitions of technical terms pertain-ing to plastics used in this test method, see Terminology D883.3.2 Definitions of Terms Speci
7、fic to This Standard:33.2.1 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 its diameter.3.2.3 bearing stressthe applied load in newtons (orpounds-force) divided by the bearing area i
8、n 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.3.2.5 maximum bearing stressthe maximum load in new-tons (or pounds-force) sustained by the specimen, divide
9、d 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 where rivets, bolts, or similarfastenings are to be used in joining members or sections. It alsois intend
10、ed 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 perpendicular to the surface.4.2 The purpose of the test is to determine the bearingstrength of the material an
11、d 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 fact that higher strength materialswill generally give higher bearing strengths, there is nosatisfactory met
12、hod 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 of the material being tested.Any test specimen preparation, conditioning, dimensions ortesting parameters o
13、r 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 default conditions apply.5. Apparatus5.1 Testing MachineA properly calibrated universal test-ing machine that c
14、an 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. The1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on
15、 Mechanical Properties.Current edition approved April 1, 2010. Published June 2010. Originallyapproved in 1948. Last previous edition approved in 2009 as D953 - 09. DOI:10.1520/D0953-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceas
16、tm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Attention is also directed to Terminology E6.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C7
17、00, West Conshohocken, PA 19428-2959, United States.percentage of error of the testing machine shall be no morethan 61 % of the applied load as determined in accordancewith Practices E4.5.2 Tension Loading FixtureA three-plate fixture of hard-ened steel similar to that shown in Fig. 1.5.3 Extension
18、IndicatorA suitable instrument reading in0.0025 mm (0.0001 in.) 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 FixtureAtype of su
19、pport with asuitable bearing pin similar to Fig. 3.5.5 Compression 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 pur
20、pose is shown in Fig. 4.6. Test Specimens6.1 The test specimens 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
21、 bearing hole are likely to givethe more precise results, although 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
22、size. The bearing hole shall be located asshown in Fig. 5. It 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. Numbe
23、r of Test Specimens7.1 At least five specimens shall be tested 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.7.3 Specimens that break a
24、t some obvious flaw shall bediscarded and retests made, unless such flaws constitute avariable the effect of which is being studied.8. Conditioning8.1 ConditioningCondition the test specimens in accor-dance with Procedure A of Practice D618, unless otherwise1Hardened spacer plate.26.3-mm (-in.) stee
25、l bolts in reamed holes.3Hardened side plate.4Extensometer 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(0.1
26、25 + 0.0010 (0.124 + 0.0000 (18) 0.0000) 0.0010)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 Loadi
27、ng Fixture1Spacer plate.2Dial gage.3Double foot ring mounted on spindle of dial gage.4Bearing pin.5Yoke mounted on specimen.6Test specimen.7Plan view of yoke.FIG. 2 Tension Loading AssemblyD953 102specified by contract or the relevant ASTM material specifica-tion. Conditioning time is specified as a
28、 minimum. Tempera-ture and humidity tolerances shall be in accordance withSection 7 of Practice D618 unless specified differently bycontract or material specification.8.2 Test ConditionsConduct tests at the same temperatureand humidity used for conditioning with tolerances in accor-dance with Sectio
29、n 7 of Practice D618 unless otherwisespecified by contract or the relevant ASTM material specifica-tion.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 hol
30、e 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.). All measurements to be made using theapplicable test methods in accordance with Test MethodD5947.10. Speed of Testing10.1 The mean rate of cro
31、sshead travel in the testing ofspecimens shall not exceed 1.3 6 0.3 mm (0.05 6 0.01in.)/min. In any 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
32、 compression loading (11.3)isoptional, but it should be recognized that Procedure B giveshigher bearing strength values than Procedure A on the samematerial. Test specimens according to both ProceduresAand Bif a complete specification of bearing strength is required.11.2 Procedure A for Tension Load
33、ingMount the speci-men to be tested in the tension loading fixture and attach adeformation indicator. 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 exhibi
34、t extended plastic flow.Such specimens tend to “neck down” in the region of thebearing hole, and it is necessary to mount the yoke 12.7 mm (12in.) below the normal position indicated in A, Fig. 1, so that itwill not slip during test.11.3 Procedure B for Compression LoadingMount thespecimen to be tes
35、ted in the compression loading fixture andload through a flat, hardened compression plate. Adjust 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
36、 in place and attach the deformation indicator (seeFig. 4).11.4 Details Common to Procedures A and 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-g
37、raphic recording is not available, record the load sustained bythe specimen for every 0.0127-mm (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.
38、 Calculation12.1 Plot the load - deflection curve for each specimen.12.2 Use a template, as described 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 deform
39、ation, N (or lbf),d = bearing hole diameter, mm (or in.), andt = specimen thickness, mm (or in.).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 f
40、igures.13. Report13.1 Report the following information:13.1.1 Complete identification of the material tested, includ-ing type, source, manufacturers code number, form, principaldimensions, and previous history,13.1.2 Direction of cutting and loading specimens,13.1.3 Conditioning procedure and enviro
41、nmental 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),1Test specimen.2Hardened steel pin.3Hardened thrust bushing.NoteCritical dimensions are as follows:TypeBea
42、ring Hole Diam-eter,mm (in.)Bearing 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)
43、FIG. 3 Steel Compression Loading FixtureD953 10313.1.6 Edge distance ratio,13.1.7 Mean rate of crosshead motion in millimetres (orinches) per minute,13.1.8 Bearing strength in Megapascals (or pounds-forceper square inch), stating whether Procedure A for tensionloading or Procedure B for compression
44、loading was used,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 dial gage foot.FIG. 4 Compression L
45、oading 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) (43414) (0.251 6 0 .001)AAll frac
46、tional dimensions shall be held to 60.40 mm (164 in.) tolerance.Edge distance ratio = B/hole diameterFIG. 5 Dimensions of Bearing Strength Test SpecimensD953 10413.1.9 Maximum bearing stress in Megapascals (or pounds-force per square inch), stating whether Procedure A or Proce-dure B was used; therm
47、oset pultruded shapes typically reportonly the maximum value, and13.1.10 The test method number and published/revisiondate.14. Precision and Bias14.1 Attempts to develop a comprehensive interlaboratoryprecision and bias statement for this test method have not beensuccessful because of the small numb
48、er of laboratories usingthis test method. However, limited precision data from onelaboratory on one material utilizing a single operator, a singleapparatus, on a single day and replicate runs of the material hasbeen provided as follows: Determinations were made on twosets of ten individual specimens
49、 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 recognized 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; plasticsAPPENDI
