1、Designation: D732 09Standard Test Method forShear Strength of Plastics by Punch Tool1This standard is issued under the fixed designation D732; 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 p
2、arentheses indicates 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 procedure for determiningthe shear s
3、trength of composite materials in the form of sheets,plates, and molded shapes 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 informationonly.1.3 This standard does not purport to ad
4、dress 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 1There is no known ISO equivalent to this standard
5、.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD4000 Classification System for Specifying Plastic Materi-alsD4066 Classification System for Nylon Injection and Ex-trusion Materials (PA)E4 Practices for Force Verification of Testing MachinesE691 Practic
6、e for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definition:3.1.1 shear strengththe maximum load required to shearthe specimen in such a manner that the moving portion of theload fixture has completely cleared the stationary portion,divided by the
7、 sheared area. It is expressed in megapascals (orpounds-force per square inch) based on the area of the shearededge or edges.4. Significance and Use4.1 Shear strength obtained by the use of punch-type toolingis one of the recognized methods of comparing materials, orobtaining data for engineering de
8、sign purposes, or both.However, it must be recognized that for end-use applicationsthere are likely to be many factors not taken into account in thistest method, such as stress-concentrating geometries and ratesof shear, which can profoundly affect the measured shearstrength. Moreover, the fact that
9、 the shear strength is calculatedby dividing the load by the area of the sheared edge (punchcircumference X specimen thickness) does not interpret asindicating the shear strength value so obtained is solely amaterial property, independent of thickness.4.2 For many materials, it is possible that ther
10、e is aspecification that requires the use of this test method, but withsome procedural modifications that take precedence whenadhering to the specification. Therefore, it is advisable to referto that material specification before using this test method.Table 1 of Classification System D4000 lists th
11、e ASTMmaterials standards that currently exist.5. Apparatus5.1 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 respec
12、t to the base. The testing machine shall also beequipped with 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 an1This tes
13、t 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 Oct. 15, 2009. Published November 2009. Originallyapproved in 1943. Last previous edition approved in 2002 as D732 02. DOI:10.
14、1520/D0732-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the e
15、nd of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.accuracy of 61 % of the indicated value or better. Theaccuracy of the testing machine shall be verified in accordancewith Practices E4.5.2 Shear ToolA shear tool of t
16、he 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 shownin Fig. 1.5.3 MicrometersSuitable micrometers for measuring thethickness of the test specimen t
17、o 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 disk cut from sheet material ormolded into this form. The thickness of the specimen is limitedfrom 1.27 and 12.7 mm (0.050 and 0.500 in.
18、). The upper andlower surfaces shall be parallel to each other and reasonablyflat. A hole approximately 11 mm (716 in.) in diameter shall bedrilled through the specimen at its center.6.2 A minimum of five specimens of each sample materialshall be tested. If fewer than five specimens are tested, ther
19、eport shall reflect that results are based on a modified versionof the standard.7. Conditioning7.1 Pre-Test ConditioningCondition the test specimens at23 6 2C (73.4 6 3.6F) and 50 6 5 % relative humidity fornot less than 40 h prior to test in accordance with Procedure Aof Practice D618 unless otherw
20、ise 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.7.2 Test ConditionsSpecimens shall be tested at a tem-perature of 23 6 2C (73.4 6 3.6F) and at 50 6 5 % rela
21、tivehumidity unless otherwise specified by contract or the relevantASTM material specification. Reference conditioning, to settledisagreements, shall apply tolerances of 61C (1.8F) and62 % relative humidity.8. Procedure8.1 Measure the thickness of each test specimen to thenearest 0.025 mm (0.001 in.
22、) at a minimum of three points ona circle approximately 12.7 mm (0.500 in.) from its center.Average the readings and record as the specimen thickness.8.2 Place the specimen over the 9.5-mm (38-in.) threadedpin of the punch and fasten it in place by securing the washerand nut tightly.NOTE 1In case of
23、 difficulty in obtaining hardened dowels and bushings, the entire shear tool may be made from a fairly good grade of steel,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 too
24、l can then be bored out to take either hardened or unhardened bushings, depending upon which are available.FIG. 1 Punch-Type Shear Tool for Testing Specimens 0.127 to 12.7 mm (0.050 to 0.500 in.) in ThicknessD732 0928.3 Center the specimen and punch on the support fixtureand complete the assembly of
25、 the clamping fixture being sureto tighten the bolts securely.8.4 Load the test specimen at a crosshead speed of 1.25 mm(0.05 in.)/min. The tolerances shall be 1.3 6 0.3 mm (0.050 60.010 in.)/min.8.5 Push the punch far enough through the specimen so thatthe sheared section clears the specimen proper
26、. The specimenwill then be adjacent to the necked-down portion of the punch,and it can then be readily removed 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 been developed and
27、 starts to fall off rapidly, thespecimen may be readily removed from both punch and die.9. Calculation9.1 Calculate shear strength in megapascals, MPa, (orpounds-force per square inch, psi), determined by dividing theload required to shear the specimen by the area of the shearededge, which shall be
28、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.,10.1.2 M
29、ethod 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 megapascals (or
30、 pounds-force persquare inch) for each specimen, the average value, and thestandard deviation.11. Precision and Bias311.1 Table 1 is based on a round-robin test conducted in1983, in accordance with Practice E691, involving six materi-als tested by eleven laboratories. Each “test result” was theavera
31、ge 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 Table 1shou
32、ld 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 E691 togenerate data sp
33、ecific 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 five specim
34、ens 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 material, obt
35、ained 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 representing the cr
36、itical 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 BiasIt is not possible to make any sta
37、tement aboutthe bias of this test method, as there is no standard referencematerial or reference test method that is applicable.3Supporting data are available from ASTM Headquarters. Request D20-1120.TABLE 1 Shear StrengthMaterialAValues Expressed in Units of Pound-Force per Square InchAverageThickn
38、ess, 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 the materials in Table 1 are: reaction inj
39、ection 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 deviations of the test results from all oft
40、he participating laboratories: Sr5 S1!21 S2!2. 1 Sn!2# /n1/2.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 between two test results = 2.8 3 Sr.ER is t
41、he 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 were greatly inferior to corresponding da
42、ta 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.).D732 09312. Keywords12.1 punch tool; shear strengthSUMMARY OF CHANGESCommittee D20 has ident
43、ified the location of selected changes to this standard since the last issue (D732 - 02)that may impact the use of this standard. (October 15, 2009)(1) Revised Sections: 1.1, 3.1.1, 4.1, 7.1, 7.2, 8.1, 8.2, 8.4, and8.5.(2) Deleted old subsection 8.1 and renumbered subsequentsections as needed.(3) Ad
44、ded 6.2 and 8.3.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 advised that determination of the validity of any such patent rights, and the riskof infringement of
45、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 reapproved or withdrawn. Your comments are invited either for revision of this standard or for ad
46、ditional 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 you feel that your comments have not received a fair hearing you shouldmake your views known to
47、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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D732 094
