散体介质SHPB被动围压试验体应力计算的理论修正方法-豆柴文库

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散体介质SHPB被动围压试验体应力计算的理论修正方法
Title:TheoreticalCorrectionsforStressCalculationinPassiveConfiningPressureTestsonSHPBDiscreteSpecimen
Introduction:
TheSplitHopkinsonPressureBar(SHPB)testhasbecomeawidelyusedexperimentaltechniqueforcharacterizingthedynamicbehaviorofsolidmaterials.Itisparticularlysuitedtoinvestigatethemechanicalpropertiesofbrittlematerials,suchasrocksandceramics,underhighstrainrates.TheSHPBtest,inpassiveconfiningpressuremode,allowsforthemeasurementofstress-strainrelationshipsatdifferentconfiningpressures.However,theaccuracyofstresscalculationsinsuchtestscanbeaffectedbyseveralfactors.ThispaperpresentsareviewofthetheoreticalcorrectionsemployedtoensureaccuratestresscalculationinpassiveconfiningpressuretestsonSHPBdiscretespecimens.
1.BackgroundonSHPBTesting:
TheSHPBtestingtechniqueinvolvestransmittinganincidentcompressivepulsethroughastrikerbarintoaspecimen,andmeasuringthereflectedandtransmittedwavesattheincidentandtransmissionbarinterfacesusingstraingauges.Real-timemeasurementsofstressandstrainareobtainedfromwhichthestress-strainrelationshipofthematerialcanbededuced.Inpassiveconfiningpressuretests,anaxialloadisappliedtothespecimenwhilemaintainingaconstantconfiningpressure.
2.FactorsAffectingStressCalculationinSHPBTests:
2.1.Inertiacorrection:Toaccountfortheinertiaofthepressurebarsduringpropagationofstresswaves,thefirstcorrectioninvolvessubtractingtheinertiatermsfromthemeasuredstressestoobtaintruestressesinthespecimen.
2.2.Elasticwavedispersioncorrection:TheclassicalSHPBtheoryassumesthatthewavepropagationinthebarsisnon-dispersive,butinreality,dispersionoccursduetotheviscoelasticnatureofthebars.Thedispersioncorrectioninvolvesdeconvolvingthestresswaveformsmeasuredinthebarstoobtainthetruestresspulsesappliedtothespecimen.
2.3.Non-uniformstressdistributioncorrection:Thestressexperiencedbythespecimenisnotuniformlydistributedduetotheimpedancemismatchattheinterfacesandthegeometryofthespecimenandbars.Correctionmethods,suchasthepulseshapingtechniqueandfiniteelementmodeli