1、Designation: E238 17aStandard Test Method forPin-Type Bearing Test of Metallic Materials1This standard is issued under the fixed designation E238; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers a pin-type bearing test ofmetallic materials to determine bearing yield strength andbearing strength.NOTE 1The presen
3、ce of incidental lubricants on the bearing surfacesmay significantly lower the value of bearing yield strength obtained bythis method.1.2 UnitsThe values stated in inch-pound units are to beregarded as standard. The values given in parentheses aremathematical conversions to SI units that are provide
4、d forinformation only and are not considered standard.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-bility
5、of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World
6、Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsB769 Test M
7、ethod for Shear Testing of Aluminum AlloysB831 Test Method for Shear Testing of Thin AluminumAlloy Products3. Terminology3.1 Definitions:3.1.1 bearing areathe product of the pin diameter andspecimen thickness.3.1.2 bearing stressthe force per unit of bearing area.3.1.3 bearing strainthe ratio of the
8、 bearing deformation ofthe bearing hole, in the direction of the applied force, to the pindiameter.3.1.4 bearing yield strengththe bearing stress at which amaterial exhibits a specified limiting deviation from the pro-portionality of bearing stress to bearing strain.3.1.5 bearing strengththe maximum
9、 bearing stress whicha material is capable of sustaining.3.1.6 edge distancethe distance from the edge of a bearingspecimen to the center of the hole in the direction of appliedforce (Fig. 1).3.1.7 edge distance ratiothe ratio of the edge distance tothe pin diameter.3.1.8 For definitions of other te
10、rms see Terminology E6.4. Significance and Use4.1 The data obtained from the bearing test are the bearingultimate and yield strength. The data provide a measure of theload-carrying capacity of a material edge loaded with aclose-fitting cylindrical pin through a hole located a specificdistance from t
11、he specimen edge.4.2 Bearing properties are useful in the comparison ofmaterials and design of structures under conditions where thepin is not restricted.5. Apparatus5.1 Testing MachinesMachines used for bearing testingshall conform to the requirements of Practices E4.5.2 Gripping DevicesVarious typ
12、es of gripping devicesmay be used to transmit the measured load applied by thetesting machine to the test specimens. Any grips considered toapply the load axially for tension testing, such as pin connec-tions or wedge grips, are satisfactory for use in bearing testing.5.3 PinThe bearing load is gene
13、rally applied to thespecimen through a close-fitting cylindrical pin. The pin shallbe harder and stronger than the material being tested. Restraint1This test method is under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.04 onUniaxial
14、 Testing.Current edition approved April 1, 2017. Published April 2017. Originallyapproved in 1964. Last previous edition approved in 2017 as E238 17. DOI:10.1520/E0238-17A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
15、nual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis intern
16、ational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Comm
17、ittee.1of movement of the specimen where it is in contact with the pinhas a considerable effect upon the hole deformation obtained asa function of the load applied. Close control of surfaceconditions on both the specimen and pin is needed to assurereproducible results. The pins used should be unifor
18、m indiameter, hardness, and surface roughness. Pin materials,hardness, and surface roughness as shown in Table 1 arerecommended for testing the materials listed. The pin shouldbe checked carefully after each test to ensure that no metallicresidue adheres to it and that it is both straight and undefo
19、rmed.If there is any question regarding its quality it should bereplaced.5.4 Pin SupportThe jig supporting the pin should positionthe pin concentric with the hole in the specimen. It should notrestrain the thickening of the specimen as the load from the pindeforms the hole. Bending of the pin should
20、 be kept to aminimum by having the jig support the pin close to thespecimen. Fig. 2 and Fig. 3 show examples of the types of jigthat have been used and are considered satisfactory.5.5 ExtensometersExtensometers used for measuring thebearing deformation shall comply with the requirements forClass B-2
21、 or better as described in Practice E83. The bearingdeformation measurement shall be made in a manner to obtainthe axial bearing deformation with a minimum of otherdeformations being included such as the bending of the pin andtensile strain in the specimen. Fig. 2 shows an adaptation of aTemplin ext
22、ensometer system to record bearing deformation.Fig. 3 illustrates a mechanism that can be used to transfer thebearing deformation so it can be measured with the sameextensometers used for tension testing. A method of measuringbearing deformation featuring two linear differential transform-ers is sho
23、wn in Fig. 4.FIG. 1 Bearing Test SpecimenTABLE 1 Characteristics of Pin for Various Materials TestedMaterial Tested MaterialRockwellHardnessSurface Roughness, in. (m) (avg)Aluminum alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Beryllium alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Cop
24、per alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Magnesium alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)Zinc alloys hardened steel C60 to 64 4 to 8 (0.1 to 0.2 m)FIG. 2 Bearing Test Fixture Used on Aluminum SheetE238 17a26. Test Specimens6.1 Specimen GeometryThe specimen shall be a f
25、lat sheettype, with the full thickness of the product being used ifpossible. If the specimen is too thick in relation to the pindiameter, the pin is likely to bend considerably or break beforethe bearing strength is obtained. If a specimen is too thin,buckling may occur. A ratio of pin diameter to s
26、pecimenthickness of from 2 to 4 has been used to avoid both conditions.The hole should have approximately the same diameter as forthe intended use. For example, if the bearing test results arebeing used to obtain data for a riveted part, a hole316 in. or14in. (5 or 6 mm) in diameter would be suitabl
27、e, while for abolted assembly, a larger hole might be desirable. A differencein test results may be obtained with holes of different diam-eters. The width of the specimen shall be 4 to 8 times thediameter of the hole. A wider specimen encourages theintended shear-out failure mode. The edge distance
28、ratio shallbe specified and the edge distance held within a tolerance of62 %. Edge distance ratios of 1.50 and 2.00 are commonlyused (see Fig. 1). A close fit between the specimen and pin isrequired, since a loose fit will tend to give lower results. Thediameter of the hole shall not exceed the pin
29、diameter by morethan 0.001 in. (0.02 mm). The free length between the point ofloading and the center of the test pin hole shall be greater than1.5 times the specimen width. The total length of the testFIG. 3 Schematic Drawing of Bearing Deformation Transfer DeviceFIG. 4 Autographic Measurement of Be
30、aring DeformationE238 17a3specimen is not critical and may depend on the method used togrip the specimen. Fig. 1 shows a bearing test specimencommonly used.6.1.1 Specimen orientationThe measured bearing proper-ties can depend on the specimen orientation and the directionin which the load is applied
31、relative to the grain flow in theproduct from which the specimen is extracted. The specimenorientation and the loading direction shall be identified by atwo-letter code as illustrated in Fig. 5. The first letter desig-nates the normal to the expected shear plane. The second letterdesignates the dire
32、ction of force application. This orientationcode is identical to that used for cylindrical and flat shearspecimens in Test Methods B769 and B831.6.1.2 The orientation codes for rectangular shaped productsare indicated in Fig. 5a. The product axes are in the longitu-dinal (L), transverse (T), and sho
33、rt (S) directions. These aresuitable for sheet, plate, extrusions, forgings, and other shapeshaving a rectangle form. The most commonly used specimenorientations are T-L and L-T for thin products. Fig. 5b showsthe orientation codes for cylindrical product forms such as rod,tube, and pipe, where the
34、product axes are in the longitudinal(L), radial (R), and circumferential (C) directions.(a)(b)FIG. 5 Pin Bearing Specimen Orientation Codes for Specimens Taken from (a) Rectangular Shapes and (b) cylindrical shapes.E238 17a46.2 Specimen PreparationA flat specimen with a holenormal to the face shall
35、be used. A smooth, round hole with aminimum of cold work on the surface must be obtained. Thefinished hole is generally bored, reamed, or ground as a finaloperation to obtain the desired degree of roundness. Any burron the periphery of the hole is indicative of a cold-workedsurface on the hole and s
36、hould be avoided. Removal of the burrwill not eliminate the cold work.7. Procedure7.1 Measurement of SpecimensMeasure the actual thick-ness of the specimen and the pin diameter, preferably readingto at least the nearest 0.5 % of the dimension measured, and inany case to at least the nearest 0.001 in
37、. (0.02 mm). Calculatethe stress on the basis of the measured dimensions. Measurethe edge distance to the nearest 0.01 in. (0.2 mm).7.2 CleaningClean the specimen, pin, and adjacent areasof the jig of all foreign matter and contamination, especiallylubricants, prior to assembly. Keep in that conditi
38、on until thetest is completed. It has been found that oil from human fingerstouching the pin significantly lowers the results of the test. Ahandle on the pin has been found to help in keeping fingersfrom touching the test area of the pin. Recommended methodsof cleaning are given in the Appendix X1.3
39、The cleanersrecommended for the materials given in the Appendix X1 aregenerally satisfactory for cleaning the pin and fixtures, too.7.3 TestingLoad the specimen and obtain simultaneousreadings of the load and bearing deformation. Any convenientmethod of load application and system of strain recordin
40、g maybe used.Autographic strain recording equipment can be readilyadapted to measure bearing deformation (see Figs. 1-6).7.4 Conduct the tests at a controlled rate of straining orloading. The recommended rate for metallic materials is 0.05bearing strain per minute. If a testing speed other than a st
41、rainrate of 0.05/min is used, report this fact.8. Determination of Bearing Yield Strength8.1 Determine the bearing yield strength from a graph of thebearing load versus bearing deformation. Fig. 6 is an illustra-tion of such a graph. Calculate the yield strength from the loadat an offset from the in
42、itial straight-line portion of the graphequal to 2 % of the pin diameter. Calculate the stress bydividing the load by the bearing area.9. Determination of Bearing Strength9.1 Calculate the bearing strength by dividing the maximumload carried by the specimen by the bearing area.10. Determination of F
43、racture Mode10.1 Determine the fracture mode of the specimen accord-ing to Fig. 7 and the descriptions of the depicted fracturemodes.10.1.1 Crushing (C): Deformation to the test pin holewithout fracture10.1.2 End Splitting (E): : A single fracture in the loadingdirection directly above the center of
44、 the test pin hole10.1.3 Shear or Shearout (S): Fracture in or within 20degrees of the loading direction of the cross section directlyabove the test pin hole10.1.4 Net-Tension (T or NT): Fracture through the speci-men transverse to the loading direction10.1.5 Diagonal Tearing (D): Tearing fracture t
45、oward thecorners of the specimen at an angle approximately 20-70degrees to the loading direction10.1.6 Multimodal Failure: If a specimen exhibits multiplemodes of failure, and it cannot be determined which is primary,multiple codes may be assigned, as appropriate.11. Report11.1 The report shall incl
46、ude the following:11.1.1 Material tested and direction of test,11.1.2 Hole diameter, width, and thickness of specimen.11.1.3 Edge distance ratio,11.1.4 Temperature of testing (if other than at roomtemperature),11.1.5 Bearing yield strength,11.1.6 Bearing strength,11.1.7 Description of fracture accor
47、ding to Fig. 7 andSection 10,11.1.8 Cleaning procedure, and11.1.9 Speed of testing.3Stickley, G. W., and Moore, A. A., “Effects of Lubrication and Pin Surface onBearing Strengths of Aluminum and Magnesium Alloys,” MTRSA, MaterialsResearch & Standards Vol 2, No. 9, pp.747, September 1962.FIG. 6 An Au
48、tographic Bearing Load Versus Bearing DeformationCurve on AZ31A-H24 Sheet at Room TemperatureE238 17a512. Precision and Bias12.1 Because of the limited number of users it is difficult tosecure information on precision or bias. Committee E28 wouldwelcome participants in an interlaboratory study to de
49、velopsuch information on this method.13. Keywords13.1 bearing strength; bearing test; bearing yield strength;metallic materials; pin-typeAPPENDIX(Nonmandatory Information)X1. RECOMMENDED METHODS OF CLEANINGX1.1 Recommended methods of cleaning the bearing testspecimen, pin, and support assembly to get uniform test resultsare given in this Appendix. They are not intended to beexclusive but have been found adequate for the materialsindicated.X1.1.1 Aluminum AlloysUltrasonic cleaning in a suitablesolvent such as acetone.X1.1.2
