Dynamic bending response of double cylindrical tubes filled with aluminum foam

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InternationalJournalofImpactEngineering38(2011)85e94

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InternationalJournalofImpactEngineering

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Dynamicbendingresponseofdoublecylindricaltubes lledwithaluminumfoam

LiuweiGuo,JilinYu*

CASKeyLaboratoryofMechanicalBehaviorandDesignofMaterials,UniversityofScienceandTechnologyofChina,Hefei,Anhui230027,People’sRepublicofChina

articleinfo

Articlehistory:

Received6April2010Receivedinrevisedform3October2010

Accepted4October2010

Availableonline12October2010Keywords:

Foam- lledstructureDoubletubestructureAluminumfoams

DynamicbendingbehaviorCrashworthiness

abstract

Thedynamicthree-pointbendingbehaviorofdoublecylindricaltubes lledwithclosed-cellaluminumfoamcorewasstudiedexperimentallyandnumerically.Itisfoundthatthedeformationmodeofthisnewstructureunderimpactloadingisdifferenttothatunderquasi-staticloading.Theloadcarryingcapacityofthestructuresubjectedtoimpactremainsatthelevelofthatinthequasi-staticsituation.Comparedwithtraditionalfoam- lledsingletubes,thespeci cenergyabsorptionef ciencyofthisnewstructureismuchhigher,andthatofbothfoam- lledstructuresinthedynamicsituationarehigherthanthatinstaticsituation.Apreliminaryexperimentalstudyontheeffectofpro lesandspanofthestructurewereperformed,andtheresultshowsthattheseparametersaffectthestructuretogether.Numericalsimulationofthebendingbehaviorwasalsoexecutedwiththeexplicit niteelementmethod.Themechanismofthedynamicresponseisrevealedbycomparisonofthemaximumstrainhistoryinthesimulation.

Ó2010ElsevierLtd.Allrightsreserved.

1.Introduction

Duringthepasttwodecades,muchresearchworkontheaxialcrushingbehaviorofthin-walledcolumnshasbeencarriedoutto ndmoreeffectiveenergyabsorbers[1e3].Ontheotherhand,astudyontherealworldvehiclecrashespresentedbyKallinaetal.[4]in1994showedthatupto90%involvedstructuralmembersfailedinbendingcollapsemode.

Thebendingresistanceofanemptythin-walledcolumntypi-callydeclinesverysigni cantlyafterreachingthepeakforceatasmallrotation.Inordertoachievehighbendingresistanceandweightef ciencyinenergyabsorption,ultra-lightcellularmetalssuchasaluminumfoamswereintroducedto llinthin-walledemptystructures.Thebendingbehaviorsofsuchstructureshavebeenstudiedbymanyresearchers.SantosaandWierzbicki[5]andSantosaetal.[6]studiedtheeffectoffoam llingonthebendingresistanceofthin-walledprismaticcolumnsthroughnumericalsimulationsandquasi-staticexperiments.Theirresultshowsthatthe llingoffoamimprovestheloadcarryingcapacitybyofferingadditionalsupportfrominsideandincreasestheenergyabsorp-tion.Chenetal.[7]performedoptimizationforminimumweightonfoam- lledsectionsunderbendingcondition.Theyshowedthepotentialofthin-walledcolumns lledwithaluminumfoamsasweight-ef cientenergyabsorbers.Chen[8]studiedthebendingbehaviorofhatpro les lledwithaluminumfoamsandfoundthat

llingofaluminumfoamsincreasedthespeci cenergyabsorptionofthestructures.Kimetal.[9]studiedthebendingcollapseofthin-walledcylindricaltubes lledwithseveralpiecesoffoamsexper-imentallyandnumerically.Hanssenetal.[10]studiedthebendingbehaviorofthefoam- lledsquareextrusionsexperimentallyandfoundthatthefoam lleralteredthelocaldeformationpatternsofthebeamssigni cantly.Reyesetal.[11]presentednumericalanalysesoffoam- lledextrusionssubjecttobending.Theyfoundthattakingfractureinboththeextrusionandthefoamintoaccountintheanalyseswasveryimportant,andthepredictedbehaviordependedonthechoiceoffracturecriterionanditscriticalvalueusedforthefoam,thestatisticalvariationoffoamdensity.

Moststudiesintheliteraturefocusedontheprismaticcolumnstructuresandmainlyunderquasi-staticloading.Inordertoimprovethecrashworthinessoffoam- lledstructureswhilekeepinghighbendingresistanceunderimpactcondition,thedynamicbendingbehaviorofanewcompositestructure,i.e.doublecylindricaltubes lledwithclosed-cellaluminumfoams,isstudiedindetailinthispaper.Dynamicexperimentsand niteelementsimulationsareperformedtoexplorethedeformationandfailuremechanismofthestructure.Theresultsarecomparedwiththoseunderquasi-staticloading[12]andthoseofemptyandfoam- lledsingletubes.2.Experimentalprocedures2.1.Materialsandspecimens

*Correspondingauthor.Tel.:þ865513600792;fax:þ865513606459.E-mailaddress:jlyu@ustc.edu.cn(J.

Yu).0734-743X/$eseefrontmatterÓ2010ElsevierLtd.Allrightsreserved.doi:10.1016/j.ijimpeng.2010.10.004

Threetypesoftubestructures,i.e.,emptytube,foam- lledsingletubeandfoam- lleddoubletube,wereusedinthe