1、Designation: D 732 02Standard Test Method forShear Strength of Plastics by Punch Tool1This standard is issued under the fixed designation D 732; 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
2、 parentheses 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. Scope *1.1 This test method covers the punch-type of shear test andis i
3、ntended for use in determining the shear strength of testspecimens of organic plastics in the form of sheets and moldeddisks in thicknesses from 1.27 to 12.7 mm (0.050 to 0.500 in.).1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informati
4、ononly.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 of regulatory limitations prior to use.NOTE 1Th
5、ere is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:D 618 Practice for Conditioning Plastics for Testing2D 4000 Classification System for Specifying Plastic Mate-rials3D 4066 Classification System for Nylon Injection and Ex-trusion Materials3E 4 Practices for Fo
6、rce Verification of Testing Machines4E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method53. Terminology3.1 Definition:3.1.1 shear strengththe maximum load required to shearthe specimen in such a manner that the moving portion hascompletely cleared the st
7、ationary portion. It is expressed inmegapascals (or pounds-force per square inch) based on thearea of the sheared edge or edges.4. Significance and Use4.1 Shear strength obtained by a tool of the punch type isone of the recognized methods of comparing materials orobtaining data for engineering desig
8、n. However, it must berecognized that for end-use application there may be manyfactors not taken into account in this test method, such asstress-concentrating geometries and rates of shear, which canprofoundly affect shear strength. Moreover, the fact that theshear strength is calculated by dividing
9、 the load by the area ofthe sheared edge (circumference X thickness) should not beinterpreted as indicating that the shear strength value soobtained is solely a material property, independent of thick-ness.4.2 For many materials, there may be a specification thatrequires the use of this test method,
10、 but with some proceduralmodifications that take precedence when adhering to thespecification. Therefore, it is advisable to refer to that materialspecification before using this test method. Table 1 of Classi-fication System D 4000 lists the ASTM materials standards thatcurrently exist.5. Apparatus
11、5.1 Testing MachineAny suitable testing machine of theconstant-rate-of-crosshead movement type. The testing ma-chine shall be equipped with the necessary drive mechanismfor imparting to the crosshead a uniform, controlled velocitywith respect to the base. The testing machine shall also beequipped wi
12、th a load-indicating mechanism capable of show-ing the total compressive load carried by the test specimen.This mechanism shall be essentially free from inertia-lag at thespecified rate of testing and shall indicate the load with anaccuracy of 61 % of the indicated value or better. Theaccuracy of th
13、e testing machine shall be verified in accordancewith Practices E 4.5.2 Shear ToolA shear tool of the punch type which is soconstructed that the specimen is rigidly clamped both to thestationary block and movable block so that it cannot bedeflected during the test. A suitable form of shear tool is s
14、hownin Fig. 1.1This 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 732 43 T. Last previous edition D 732 99.
15、2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 08.02.4Annual Book of ASTM Standards, Vol 03.01.5Annual Book of ASTM Standards, Vol 14.02.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
16、 West Conshohocken, PA 19428-2959, United States.5.3 MicrometersSuitable micrometers for measuring thethickness of the test specimen to an incremental discriminationof at least 0.025 mm (0.001 in.).6. Test Specimen6.1 The specimen shall consist of a 50-mm (2-in.) square ora 50-mm (2-in.) diameter di
17、sk cut from sheet material ormolded into this form. The thickness of the specimen may befrom 1.27 to 12.7 mm (0.050 to 0.500 in.). The upper and lowersurfaces shall be parallel to each other and reasonably flat. Ahole approximately 11 mm (716 in.) in diameter shall be drilledthrough the specimen at
18、its center.7. Conditioning7.1 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. Referen
19、ce pre-test con-ditioning, to settle disagreements, shall apply tolerances of61C (1.8F) and 62 % relative humidity.7.2 Test ConditionsCondition 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 61
20、8 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 62 % relative humidity.8. Procedure8.1 Use five specimens.8.2 Measure the thickness of the test specimen with asuita
21、ble micrometer to the nearest 0.025 mm (0.001 in.) atseveral points 12.7 mm (0.500 in.) from its center.8.3 Place the specimen over the 9.5-mm (38-in.) pin of thepunch and fasten tightly to it by means of the washer and nut.Then assemble the tool jig and tighten the bolts.8.4 Maintain the crosshead
22、speed of the machine during thetest at 1.25 mm (0.05 in.)/min, measured when the machine isrunning idle. The tolerances should be 1.3 6 0.3 mm (0.050 60.010 in.)/min.NOTE 1In case of difficulty in obtaining hardened dowels and bushings, the entire shear tool may be made from a fairly good grade of s
23、teel,eliminating all of the bushings shown. The actual working surfaces will wear faster than when hardened tool steel is used. When they show signs ofappreciable wear, the shear tool can then be bored out to take either hardened or unhardened bushings, depending upon which are available.Table of Me
24、tric Equivalentsin.mm183.2146.4389.51212.70.98424.90.99925.1125.411828112381784725121854376314824102418105FIG. 1 Punch-Type Shear Tool for Testing Specimens 0.127 to 12.7 mm (0.050 to 0.500 in.) in ThicknessD7320228.5 Push down the punch far enough so that the shoulderclears the specimen proper. The
25、 specimen will then be adjacentto the necked-down portion of the punch, and it should bepossible to remove the specimen readily from the tool.NOTE 2For thick specimens of some materials the punched-out piecetends to stick in the die. If the test is continued only to the point wheremaximum load has b
26、een developed and starts to fall off rapidly, thespecimen may be readily removed from both punch and die.9. Calculation9.1 Calculate shear strength in megapascals (or pounds-force per square inch), determined by dividing the loadrequired to shear the specimen by the area of the sheared edge,which sh
27、all be taken as the product of the thickness of thespecimen by the circumference of the punch.10. Report10.1 Report the following information:10.1.1 Complete identification of the material tested, includ-ing type, source, manufacturers code number, form, principaldimensions, previous history, etc.,1
28、0.1.2 Method of test, type of test specimen, and dimen-sions,10.1.3 Atmospheric conditions in the test room,10.1.4 Conditioning procedure used,10.1.5 Diameter of punch,10.1.6 Load in newtons (or pounds-force) required to sheareach specimen, and the average value, and10.1.7 Shear strength in megapasc
29、als (or pounds-force persquare inch) for each specimen, the average value, and thestandard deviation.11. Precision and Bias611.1 Table 1 is based on a round-robin test conducted in1983, in accordance with Practice E 691, involving six mate-rials tested by eleven laboratories. Each “test result” was
30、theaverage of five individual determinations. Each laboratoryobtained one test result for each material.NOTE 3Caution: The following explanations of r and R (11.2-11.2.3)are intended only to present a meaningful way of considering theapproximate precision of these test methods. The data given in Tab
31、le 1should not be applied rigorously to the acceptance or rejection ofmaterials, as those data are specific to the round robin and may not berepresentative of other lots, conditions, materials, or laboratories. Users ofthis test method should apply the principles outlined in Practice E 691 togenerat
32、e data specific to their laboratory and materials, or between specificlaboratories. The principles of 11.2-11.2.3 would then be valid for suchdata.11.2 Concept of r and R in Table 1If Srand SRhave beencalculated from a large enough body of data, and for test resultsthat were averages from testing fi
33、ve specimens for each testresult, then:11.2.1 RepeatabilityTwo test results obtained within onelaboratory shall be judged not equivalent if they differ by morethan the r value for that material. The r value is the intervalrepresenting the critical difference between two test results forthe same mate
34、rial, obtained by the same operator using thesame equipment on the same day in the same laboratory.11.2.2 ReproducibilityTwo test results obtained by differ-ent laboratories shall be judged not equivalent if they differ bymore than the R value for that material. The R value is theinterval representi
35、ng the critical difference between two testresults for the same material, obtained by different operatorsusing different equipment in different laboratories.11.2.3 The judgments in 11.2.1 and 11.2.2 will have anapproximately 95 % (0.95) probability of being correct.11.3 BiasNo statement may be made
36、about the bias of thistest method, as there is no standard reference material orreference test method that is applicable.12. Keywords12.1 punch tool; shear strength6Supporting data are available from ASTM Headquarters. Request RR: D20-1120.TABLE 1 Shear StrengthMaterialAValues Expressed in Units of
37、Pound-Force per Square InchAverageThickness, in.Mean SrBSRCrDRERIM 0.134 2 900 32 155 92 439HDPE 0.071 3 410 27 135 76 382Polyester 0.128 8 580 57 278 163 788SMC 0.210 14 700 304 569 862 1 610PolyesterFPCTFEF0.01040.007610 2007 9003845281 9502 7301 0801 4905 5307 740AThe complete designations for th
38、e materials in Table 1 are: reaction injection molding (RIM), high-density polyethylene (HDPE), sheet molding compound (SMC), andpolychlorotrifluoroethylene (PCTFE).BSris the within-laboratory standard deviation for the indicated material. It is obtained by pooling the within-laboratory standard dev
39、iations of the test results from all ofthe participating laboratories: Sr5 S1!21 S2!2. 1 Sn!2# /n#1/2.CSRis the between-laboratory reproducibility, expressed as standard deviation: SR5 $Sr21 SL2%1/2where SLis the standard deviation of laboratory means.Dr is the within-laboratory critical interval be
40、tween two test results = 2.8 3 Sr.ER is the between-laboratory critical interval between two test results = 2.8 3 SR.FValues for 0.010 in. thick polyester specimens and 0.007 in. thick PCTFE specimens are included in Table 1 to show that the repeatability and reproducibility of shearstrength values
41、were greatly inferior to corresponding data obtained on specimens of 1.780 mm (0.070 in.) minimum thickness. Therefore, the scope of this test methodwas revised to limit test specimen thickness to the range from 1.27 to 12.7 mm (0.050 to 0.500 in.).D732023SUMMARY OF CHANGESThis section identifies th
42、e location of selected changes to this test method. For the convenience of the user,Committee D20 has highlighted those changes that may impact the use of this test method. This section may alsoinclude descriptions of the changes or reasons for the changes, or both.D 732 - 02:(1) Revised 7.1 and 7.2
43、.D 732 - 99:(1) Changes to scope, ISO equivalency statement added,precision and bias statement placed in appropriate format, andkeywords added.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of th
44、is standard are expressly advised 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 ye
45、ars andif not revised, either reapproved 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 commi
46、ttee, which you may attend. If you 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).D732024
