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Abstract
ABSTRACT
inPolycarbonateisakindofamorphouspolymer.Ithasbeenusedextensively
sj是什么automobileandaviationfieldsduetoitsexcellenttransparencyandgoodimpacttoughness.Atpresent,theresearchesonthetemperature-dependentdynamicpropertiesofpolycarbonatemainlyfocusonitsdynamiccompressionresponses·I÷hasbeenwellknownthatthereexistsobviousdifferencesbetweenthetensionand
andthecrazinganddeformationlocalizationcompressionstress.strainresponses
polymers.Consequently,itisnecessarytoOCCUrduringtensileloadingforamorphous
thedynamictensionbehaviorofpolycarbonate.However,investigateandcharacterizeconner
duetothetestingtechniquedifficulties,verylittleresearchhasbeenreportedonthedress的复数
tensionresponsesofpolycarbonateathighstrainrates.
Forlow.impendenceand.10w-strengthpolymericmaterials,thespecimen氟怎么读
geometryusedinHopkinsonbartestsisdeterminedandthehighsignal·to—noiseratiooftransmittedpulsesisobtained.Thedynamictensionexperimentaltechniqueforpolymersisachievedusingrotating·diskindirectbar-bartensileimpactapparatus·Thequasi—static,moderatestrain·rateanddynamictensiontestsarecarriedoutto
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andstrainrateonthetensionstress。straininvestigatetheeffectsoftemperature
responsesofpolycarbonateoverwiderangesoftemperatures(213_393K)andstrainrates(O.001.1700sq).Experimentalresultsindicatethatthetensionbehaviorof
kcoandpolycarbonateexhibitscomplexnonlinearcharacteristicsincludingviscoelasticity
andstrainhardening.Thetensileimpactviscoplasticitysuchasstrainsoftening
loading-unloadingtestisconductedtoevaluatetheelasticbehaviorofpolycarbonateathi。ghstrainrates.Experimentalresultsconfirmthatthestress—strainresponsepriortothepeakstressiselasticandthepeakpointinthestress—straincurvecanbe
consideredastheinitialyieldingpoint.Itisfoundthatthetensionpropertiesof
andstrainrate.Thepolycarbonatearesignificantlydependentonthetemperature
valuesofyieldstrengthandyieldstrainincreasewithdecreasingtemperatureand
rate.Furthermore,theyieldstrengthhasobviousnonlinearincreasingstrain
withlogarithmstrainratewithintheraterangeinvestigatedinthepresentrelationship
Papel"·
Basedontheaforementionedexperimentalwork,aphenomenologica!viscoelasticconstitutivemodelincorporatingtemperatureeffectisproposed.The
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