ASTM_D_945_-_06_2012.pdf

Designation:D94506(Reapproved 2012)Standard Test Methods forRubber Properties in Compression or Shear(MechanicalOscillograph)1This standard is issued under the fixed designation D945;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.Scope1.1 These test methods cover the use of the Yerzley me-chanical oscillograph for measuring mechanical properties ofrubber vulcanizates in the generally small range of deformationthat characterizes many technical applications.These proper-ties include resilience,dynamic modulus,static modulus,kinetic energy,creep,and set under a given force.Measure-ments in compression and shear are described.2,31.2 The test is applicable primarily,but not exclusively,tomaterials having static moduli at the test temperature such thatforces below 2 MPa(280 psi)in compression or 1 MPa(140 psi)in shear will produce 20%deformation,and havingresilience such that at least three complete cycles are producedwhen obtaining the damped oscillatory curve.The range maybe extended,however,by use of supplementary masses andrefined methods of analysis.Materials may be compared eitherunder comparable mean stress or mean strain conditions.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 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.For a specificwarning see 12.14.2.Referenced Documents2.1 ASTM Standards:4D832 Practice for Rubber Conditioning For Low Tempera-ture TestingD1207 Recommended Practice for Classifying ElastomericCompounds for Resilient Automotive Mountings(With-drawn 1971)5D4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries2.2SAE Standard:SAE J16 Classification of Elastomer Compounds for Auto-motive Resilient Mountings6,73.Terminology3.1 Descriptions of Terms Specific to This Standard:3.2 effective dynamic moduluscalculated from the formulafor simple harmonic motion in a damped free oscillation.It isa composite index which includes the effect of such diversefactors as nonlinearity of stress-strain,changing molecularenergies,and heat losses.3.3 point modulusratio of total stress(force/area)to totalstrain(change in dimension/unstressed dimension)at one pointof the stress-strain curve.Sometimes called the“secantmodulus,”it is equal to the slope of a line from the origin to thechosen point.3.4 static modulussynonymous with“tangent modulus”and is the slope of the tangent to the stress-strain curve at a1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.10 on PhysicalTesting.Current edition approved Dec.1,2012.Published February 2013.Originallyapproved in 1948.Last previous edition approved in 2006 as D945 06.DOI:10.1520/D0945-06R12.2A survey of some aspects of hysteresis and modulus in dynamic performanceof polymers is available in a paper by Payne,A.R.,“The Role of Hysteresis inPolymers,”Rubber Journal,January 1964,p.36.3One method of correlating fundamental data from theYerzley oscillograph withdynamic tests at constant amplitude is described by Baldwin,F.P.,in his paper,“Determination of the Dynamic Properties of Rubberlike Materials by Means of aModified Yerzley Oscillograph,”The Rubber Age,April 1950.4For 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.5The last approved version of this historical standard is referenced onwww.astm.org.6Available from Society of Automotive Engineers,400 Commonwealth Drive,Warrendale,PA 15096.7The Yerzley oscillograph was originally described in detail in the paper byYerzley,F.L.,“A Mechanical Oscillograph for Routine Tests of Rubber andRubber-Like Materials,”Proceedings,ASTM,Vol 39,1939,p.1180;also RubberChemistry and Technology,Vol XIII,No.1,January 1940,p.149.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 chosen point.It can provide a reference for comparison withthe effective dynamic modulus at that point.4.Summary of Test Methods4.1 Specimens are loaded by an unbalanced lever and theresultant deflections are recorded on a chronograph.Thispermits calculations to be made of static modulus at any stageof a stepwise loading or unloading schedule.Creep an