ASTM_D_732_-_10.pdf

Designation:D73210Standard 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 parentheses 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 U.S.Department of Defense.1.Scope*1.1 This test method covers the procedure for determiningthe shear strength 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 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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD4000 Classification System for Specifying Plastic Materi-alsE4 Practices for Force Verification of Testing MachinesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions: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 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 design 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 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 there 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 the 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 respect 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 anaccuracy 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 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.Asuitable form of shear tool is shownin Fig.1.5.3 MicrometersSuitable micrometers for measuring thethickness of the test specimen to an incremental discriminationof at least 0.025 mm(0.001 in.).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 1,2010.Published April 2010.Originallyapproved in 1943.Last previous edition approved in 2009 as D732 09.DOI:10.1520/D0732-10.2For 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.*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 States1 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.).The upper andlower surfaces shall be parall