ASTM D953-2009 Standard Test Method for Bearing Strength of Plastics.pdf

1、Designation: D953 09Standard 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 PlasticsD4066 Classification System for Nylon Injecti

6、on and Ex-trusion Materials (PA)D5947 Test Methods for Physical Dimensions of 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

7、used in this test method, see Terminology D883.3.2 Definitions of Terms Specific 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 str

8、essthe 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.3.2.5 maximum bearing stressthe

9、 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 where rivets, bolts, or simi

10、larfastenings 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 perpendicular to the surface.4.2 T

11、he 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 fact that higher strength mater

12、ialswill 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 of the material being tested.A

13、ny 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 default conditions apply.5. Appara

14、tus5.1 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 of1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcomm

15、ittee D20.10 on Mechanical Properties.Current edition approved Nov. 15, 2009. Published December 2009. Originallyapproved in 1948. Last previous edition approved in 2002 as D953 - 02. DOI:10.1520/D0953-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S

16、ervice at serviceastm.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 Harb

17、or Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.material it may be necessary to operate at a slower speed. Thepercentage 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 thre

18、e-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.) 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 accessor

19、ies forthis purpose is shown in Fig. 2.5.4 Compression Loading FixtureAtype of support 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

20、pin in thecompression loading fixture. A suggested dial gage assemblyfor this purpose 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

21、and the type of loading under consideration. Thethicker specimens with the larger 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

22、tofail prematurely. The specimen may be machined from sheet ormolded to finished 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 rea

23、mingoperation 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 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

24、tested for eachsample in case of anisotropic materials.7.3 Specimens that break at 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 at 23 62C (73.4 6 3.6F) and

25、 50 6 10 % relative humidity for not1Hardened spacer plate.26.3-mm (-in.) steel 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.)Thic

26、kness 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) 0.0010)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 (0.00

27、1to 0.005 in.) greater than the specimen under test.FIG. 1 Steel Tension Loading 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 092less than 40 h prior to t

28、est in accordance with Procedure A ofPractice D618, unless otherwise specified by contract or therelevant ASTM material specification. Reference pre-test con-ditioning, to settle disagreements, shall apply tolerances of61C (1.8F) and 65 % relative humidity.8.2 Test ConditionsConduct tests at 23 6 2C

29、 (73.4 63.6F) and 50 6 10 % relative humidity, unless otherwisespecified by contract or the relevant ASTM material specifica-tion. Reference testing conditions, to settle disagreements,shall apply tolerances of 61C (1.8F) and 65 % relativehumidity.9. Measurement of Dimensions9.1 Measure the width an

30、d 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 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.)

31、. All measurements to be made using theapplicable test methods in accordance with Test MethodD5947.10. 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 case the crosshead movement shall be slowenough so that

32、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 bearing strength values than Procedure A on the samematerial

33、. Test specimens according to both ProceduresAand 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 indicator. If a dial gage (Fig. 2) is used, adjust theyoke so tha

34、t 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 it is necessary to mount the yoke 12.7 mm (12in.) below the

35、 normal position indicated in A, Fig. 1, so that itwill 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 theclearance between the thrust bushings of the loading fi

36、xturesuch 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 and BTake care inaligning the long axis of the specimen with

37、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 (0.0005-in.) deformationup to a total deformation of 4 % of

38、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 described in the Appendix, todetermine the load at 4 % hole defo

39、rmation.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.).12.4 Calculate the arithmetic mean of the observations andr

40、eport 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 material tested, includ-ing type, source, manufacturers code nu

41、mber, form, principaldimensions, and previous history,13.1.2 Direction of cutting and loading specimens,13.1.3 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),1Test specimen.2Harden

42、ed steel pin.3Hardened thrust bushing.NoteCritical dimensions are as follows:TypeBearing 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

43、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 Loading FixtureD953 09313.1.5 Diameter of bearing hole, in millimetres (or inches),13.1.6 Edge distance ratio,13.1.7 Mean rate of crosshead motion in millimetres (orinches) per minute,13.1.8

44、Bearing strength in Megapascals (or pounds-forceper square inch), stating whether Procedure A for tensionloading or Procedure B for compression loading was used,1Test specimen. 6Dial gage.2Bearing pin. 7Pedestal support.3Thrust bushings. 8Clamp for cheek blocks.4Hanger for dial gage. 9Hard maple che

45、ek blocks to stabilize test specimen.5Spring-supported thrust member of transfer deforma-tion of specimen to dial 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

46、) (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 fractional dimensions shall be held to 60.40 mm (164 in.) tolerance.Edge distance ratio = B/hole diameterFIG. 5 Dimensions of Bearing Strength Test SpecimensD95

47、3 09413.1.9 Maximum bearing stress in Megapascals (or pounds-force per square inch), stating whether Procedure A or Proce-dure B was used; thermoset pultruded shapes typically reportonly the maximum value, and13.1.10 The test method number and published/revisiondate.14. Precision and Bias14.1 Attemp

48、ts to develop 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,

49、 on a single 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 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