ASTM_D_747_-_10.pdf

Designation:D74710Standard Test Method forApparent Bending Modulus of Plastics by Means of aCantilever Beam1This standard is issued under the fixed designation D747;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 determination of the appar-ent bending modulus2of plastics by means of a cantileverbeam.It is well suited for determining relative flexibility ofmaterials over a wide range.It is particularly useful formaterials too flexible to be tested by Test Methods D790.1.2 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:3D618 Practice for Conditioning Plastics for TestingD790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsD4000 Classification System for Specifying Plastic Materi-alsD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 apparent bending modulusan apparent modulus ofelasticity obtained in flexure,using a cantilever beam testingapparatus,where the deformation involved is not purely elasticbut contains both elastic and plastic components.4.Significance and Use4.1 This test method provides a means of deriving theapparent bending modulus of a material by measuring forceand angle of bend of a cantilever beam.The mathematicalderivation assumes small deflections and purely elastic behav-ior.Under actual test conditions,the deformation has bothelastic and plastic components.This test method does notdistinguish or separate these,and hence a true elastic modulusis not calculable.Instead,an apparent value is obtained and isdefined as the apparent bending modulus of the material.Thetangent modulus obtained by Test Methods D790 is preferred,when the material can be tested by the Test Methods D790 testprocedure.4.2 Because of deviations from purely elastic behavior,changes in span length,width,and depth of the specimen willaffect the value of the apparent bending modulus obtained;therefore,values obtained from specimens of different dimen-sions are not necessarily comparable.4.3 Rate of loading is controlled only to the extent that therate of angular change of the rotating jaw is fixed at 58 to66/min.Actual rate of stressing will be affected by spanlength,width,depth of the specimen,and weight of thependulum.4.4 For many materials,there are specifications that requirethe use of this test method,but with some procedural modifi-cations that take precedence when adhering to the specifica-tion.Therefore,it is advisable to refer to that material speci-fication before using this test method.Table 1 of ClassificationSystem D4000 lists the ASTM materials standards that cur-rently exist.NOTE2A discussion of the theory of obtaining a purely elasticbending modulus,using a cantilever beam testing apparatus,can be foundin Appendix X1.The results obtained under actual test conditions will be1This 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 2008 as D747-08.DOI:10.1520/D0747-10.2This property was designated stiffness in versions of this test method issuedprior to 1984.3For 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 the apparent bending modulus.5.Apparatus5.1 The apparatus for the apparent bending modulus test,asshown in Fig.1,shall be the cantilever beam bending type,consisting essentially of the following:5.1.1 ViseA motor-driven specimen vise,V,with handcrank for initial loading,to which the pointer indicator I2isattached,and wh