1、Designation: E 238 84 (Reapproved 2002)Standard Test Method forPin-Type Bearing Test of Metallic Materials1This standard is issued under the fixed designation E 238; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a pin-type bearing test ofmetallic materials to determine bearing yield strength andbearing streng
3、th.NOTE 1The presence of incidental lubricants on the bearing surfacesmay significantly lower the value of bearing yield strength obtained bythis method.1.2 The values stated in inch-pound units are to be regardedas the standard.1.3 This standard does not purport to address all of thesafety concerns
4、, 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 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E4 Practices for Force Verification of Testi
5、ng Machines2E6 Terminology Relating to Methods of Mechanical Test-ing2E83 Practice for Verification and Classification of Exten-someters23. 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
6、bearing strainthe ratio of the bearing deformationof the bearing hole, in the direction of the applied force, to thepin diameter.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
7、.5 bearing strengththe maximum bearing stress whicha material is capable of sustaining.3.1.6 edge distancethe distance from the edge of a bear-ing specimen to the center of the hole in the direction ofapplied force (Fig. 1).3.1.7 edge distance ratiothe ratio of the edge distance tothe pin diameter.3
8、.1.8 For definitions of other terms 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 l
9、ocated a specificdistance from the specimen edge.4.2 Bearing properties are useful in the comparison ofmaterials and design of structures under conditions where thepin is not restricted.1This test method is under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsib
10、ility of Subcommittee E 28.05 onCompression Testing.Current edition approved July 27, 1984. Published November 1984. Originallypublished as E 238 64. Last previous edition E 238 68 (1978).2Annual Book of ASTM Standards, Vol 03.01.FIG. 1 Bearing Test Specimen1Copyright ASTM International, 100 Barr Ha
11、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Apparatus5.1 Testing MachinesMachines used for bearing testingshall conform to the requirements of Practices E4.5.2 Gripping DevicesVarious types of gripping devicesmay be used to transmit the measured load applied by thetes
12、ting 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 generally applied to thespecimen through a close-fitting cylindrical pin. The pin sha
13、llbe harder and stronger than the material being tested. Restraintof 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
14、 assurereproducible results. The pins used should be uniform 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 metallicre
15、sidue adheres to it and that it is both straight and undeformed.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 l
16、oad from the pindeforms the hole. Bending of the pin should 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
17、deformation shall comply with the requirements forClass B-2 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
18、in the specimen. Fig. 2 shows an adaptation of aTemplin extensometer 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 deforma
19、tion featuring two linear differential transform-ers is shown in Fig. 4.6. Test Specimens6.1 Specimen DimensionsThe specimen shall be a flatsheet type, with the full thickness of the product being used ifpossible. If the specimen is too thick in relation to the pindiameter, the pin is liable to bend
20、 considerably or break beforethe bearing strength is obtained. If a specimen is too thin,buckling may occur. A ratio of pin diameter to specimenthickness 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
21、 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 suitable, 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 s
22、pecimen should be about 4 to 8 timesthe hole diameter. The edge distance ratio shall be specified andthe edge distance held within a tolerance of 62 %. Edgedistance ratios of 112 and 2 are commonly used (see Fig. 1). Aclose fit between the specimen and pin is required since a loosefit will tend to g
23、ive lower results. The diameter of the holeshould not exceed the pin diameter by more than 0.001 in.(0.02 mm). The total length of the test specimen is not criticaland may depend on the method used to grip the specimen. Fig.1 shows a bearing test specimen commonly used.6.2 Specimen PreparationA flat
24、 specimen with a holenormal to the face shall 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 indica
25、tive of a cold-workedsurface on the hole and should 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, a
26、nd inany case to at least the nearest 0.001 in. (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, especiallylubri
27、cants, prior to assembly. Keep in that condition 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 met
28、hodsof cleaning are given in the Appendix X1.3The 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
29、load application and system of strain recording maybe used.Autographic strain recording equipment can be readilyadapted to measure bearing deformation (see Figs. 1-5).7.4 Conduct the tests at a controlled rate of straining orloading. The recommended rate for metallic materials is 0.05bearing strain
30、per minute. If a testing speed other than a strainrate of 0.05/min is used, report this fact.3Stickley, G. W., and Moore, A. A., “Effects of Lubrication and Pin Surface onBearing Strengths of Aluminum and Magnesium Alloys,” Materials Research bearing test; bearing yield strength;metallic materials;
31、pin-typeFIG. 4 Autographic Measurement of Bearing DeformationFIG. 5 An Autographic Bearing Load Versus Bearing DeformationCurve on AZ31A-H24 Sheet at Room TemperatureE 238 84 (2002)4APPENDIX(Nonmandatory Information)X1. RECOMMENDED METHODS OF CLEANINGX1.1 Recommended methods of cleaning the bearing
32、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 Magnesium AlloysChemical c
33、leaning with acleaner such as one consisting of 60 g of NaOH plus 10 g ofNa3PO412H2O/L of water at 180 to 200F.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advise
34、d that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either re
35、approved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If y
36、ou feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E 238 84 (2002)5
