Further investigation on the dynamic compressive strength enhancement

Further investigation on the dynamic compressive strength enhancement of concrete-like materials based on split Hopkinson pressure bar tests. Part II Numerical simulations

InternationalJournalofImpactEngineering36(2009)1335–1345

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InternationalJournalofImpactEngineering

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http://www.77cn.com.cn/locate/ijimpeng

Furtherinvestigationonthedynamiccompressivestrengthenhancementofconcrete-likematerialsbasedonsplitHopkinsonpressurebartests.PartII:Numericalsimulations

Q.M.Lia,b,*,Y.B.Lua,H.Mengc

a

SchoolofMechanical,AerospaceandCivilEngineering,PariserBuilding,TheUniversityofManchester,P.O.Box88,ManchesterM601QD,UKStateKeyLaboratoryofExplosionScienceandTechnology,BeijingInstituteofTechnology,Beijing100081,Chinac

WuhanConstructionProjectQualitySupervisionStation,JiansheRoad721#,Wuhan430015,China

b

articleinfo

Articlehistory:

Received1April2008Accepted17April2009

Availableonline27May2009Keywords:

Concrete-likematerials

SplitHopkinsonpressurebarCompressivestrengthKineticfrictionmodelNumericalsimulation

abstract

SplitHopkinsonpressurebar(SHPB)testshavebeenusedwidelytomeasurethedynamiccompressivestrengthofconcrete-likematerialsathighstrain-ratesbetween101and103sÀ1.Ithasbeenshownincompanionpaper(ZhangM,WuHJ,LiQM,HuangFL.Furtherinvestigationonthedynamiccompressivestrengthenhancementofconcrete-likematerialsbasedonsplitHopkinsonpressurebartestsPartI:Experiments.IntJImpactEng2009;36(12):1327–1334)thattheaxialstrainaccelerationisnormallyunavoidableinanSHPBtestonbrittlematerials.Axialstrainaccelerationintroducesradialcon nementintheSHPBspecimensandconsequentlyenhancesthecompressivestrengthofconcrete-likespecimens.Thispaperemploysnumericalsimulationtofurtherdemonstratethattheunexpectedradialcon nementinanSHPBtestisresponsiblefortheincreaseofthedynamiccompressivestrengthofconcrete-likematerialsatstrain-ratesfrom101to103sÀ1.Itcon rmstheobservationsinZhangetal.(ZhangM,WuHJ,LiQM,HuangFL.Furtherinvestigationonthedynamiccompressivestrengthenhancementofconcrete-likematerialsbasedonsplitHopkinsonpressurebartestsPartI:Experiments.IntJImpactEng2009;36(12):1327–1334)thatthedynamicincreasefactor(DIF)measuredinSHPBtestscanbereducedeitherbyusingtubularSHPBspecimensorbyreducingthediameteroftheSHPBspecimen.Akineticfrictionmodelisproposedbasedonkineticfrictiontestsandisimplementedinthenumericalmodel.Itshowsthatitisnecessarytouseakineticfrictionmodel,ratherthanaconstantfrictionmodel,formoreaccuratenumericalsimulationofSHPBtests.

Ó2009ElsevierLtd.Allrightsreserved.

1.Introduction

Strain-rateeffectsonthecompressivestrengthofvariousconcrete-likematerials,e.g.,concrete,mortar,rocketc,havebecomeanimportantconsiderationinthematerialstrengthmodelinnumericalanalysisanddesignoftheprotectivestructuresmadefromconcrete-likematerials.Itisgenerallyacceptedthatthedynamiccompressivestrengthofconcrete-likematerialsincreaseswithstrain-rate,whichisrepresentedbyadynamicincreasefactor(DIF)de nedbytheratioofthedynamicstrengthtothequasi-staticstrengthinuncon neduniaxialcompression.

*Correspondingauthor.SchoolofMechanical,AerospaceandCivilEngineering,PariserBuilding,TheUniversityofManchester,P.O.Box88,ManchesterM601QD,UK.

E-mailaddress:qingming.li@manchester.ac.uk(Q.M.

Li).0734-743X/$–seefrontmatterÓ2009ElsevierLtd.Allrightsreserved.doi:10.1016/j.ijimpeng.2009.04.010

Agreatnumberoftestshavebeenperformedto ndthedependenceofDIFonstrain-rateusingvarioustestmethods,e.g.,drop-hammertechniques,servo-hydraulicloadingrigs,explosivedevicesandsplitHopkinsonpressurebar(SHPB)technique.CriticalreviewswereconductedbyBischoffandPerry[1]andWilliams[2],wheretheDIFofconcretemeasuredbyvariousexperimentaltechniqueswassummarized.Inpasttwodecades,theSHPBtech-nique,whichwasdevelopedoriginallytomeasurethedynamic owstress–strainrelationsofplasticmaterials,hasbeenappliedtodeterminethedynamiccompressivestrengthofbrittlematerialsinawiderangeofstrain-ratesbetween101and103sÀ1.

Ithasbeenrealizedthatradialinertiaeffectsareassociatedwith

_=dts0)inan3z¼d3theunavoidableaxialstrainacceleration(i.e.

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