2011 Vol. 31, No. 4
Display Method:
2011, 31(4): 337-342.
doi: 10.11883/1001-1455(2011)04-0337-06
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Abstract:
Gaseousdetonationpropagationof2H2/O2/Armixtureinanannulartubewasexperimentallyandnumericallyinvestigated. Detonationcellularpatternswererecordedbysmokedfoils.The second-orderadditivesemi-implicitRunge-Kutta(ASIRK)methodandthefifth-orderweightedessentiallynon- oscillatory(WENO)schemewereusedtodiscretizethetimetermandthespatialderivatives, respectively.Adetailedchemicalreactionmechanism modelwasappliedtodescribetheprocessesofdetonationchemicalreactions. Numericalcellularpatternsanddetonationflowfieldwereobtained. Experimentalandnumericalresultsshowthatwhiledetonationpropagatesintheannular tube,duetotheconvergenceoftheouterwallandthedivergenceoftheinnerwall,thedetonationintensityalongtheinnerwallislowerthanthatalongtheouterwall, andthecellsizeismuchlarger. ThedistributionregionofOHalongtheinnerwallisalsowiderthanthatalongtheouterwall,and theconcentrationissmaller.Justbecauseofthecharacterofarotatingdetonation,thedetonation wavescanrotatearoundanaxisatasteadyangularvelocity.
Gaseousdetonationpropagationof2H2/O2/Armixtureinanannulartubewasexperimentallyandnumericallyinvestigated. Detonationcellularpatternswererecordedbysmokedfoils.The second-orderadditivesemi-implicitRunge-Kutta(ASIRK)methodandthefifth-orderweightedessentiallynon- oscillatory(WENO)schemewereusedtodiscretizethetimetermandthespatialderivatives, respectively.Adetailedchemicalreactionmechanism modelwasappliedtodescribetheprocessesofdetonationchemicalreactions. Numericalcellularpatternsanddetonationflowfieldwereobtained. Experimentalandnumericalresultsshowthatwhiledetonationpropagatesintheannular tube,duetotheconvergenceoftheouterwallandthedivergenceoftheinnerwall,thedetonationintensityalongtheinnerwallislowerthanthatalongtheouterwall, andthecellsizeismuchlarger. ThedistributionregionofOHalongtheinnerwallisalsowiderthanthatalongtheouterwall,and theconcentrationissmaller.Justbecauseofthecharacterofarotatingdetonation,thedetonation wavescanrotatearoundanaxisatasteadyangularvelocity.
2011, 31(4): 343-348.
doi: 10.11883/1001-1455(2011)04-0343-06
Abstract:
Thecomparabilityruleonhydrodynamicsimpactwasdescribedandvalidatedwiththedimensionanalysismethod. ThemodifiedSPH methodwasusedtosimulatethethintargetpenetration toevaluatethecomparabilityrule.Itisdemonstratedthatthecomparabilityruleonhypervelocityimpactisaccurateandfeasibleanditissignificantfortheexperiments
Thecomparabilityruleonhydrodynamicsimpactwasdescribedandvalidatedwiththedimensionanalysismethod. ThemodifiedSPH methodwasusedtosimulatethethintargetpenetration toevaluatethecomparabilityrule.Itisdemonstratedthatthecomparabilityruleonhypervelocityimpactisaccurateandfeasibleanditissignificantfortheexperiments
2011, 31(4): 349-354.
doi: 10.11883/1001-1455(2011)04-0349-06
Abstract:
Thedifferencesoftheload-bearingstateandtheintensitywereconsideredbetweensteeland concretewhileastructurecollapsing.Acommonnodeseparatemodelwasadoptedtosimulatethe collapseprocessofareinforcedconcretestructurebyusingthefiniteelementanalysissoftwareANSYS/ LS-DYNA.Aseriesofanalysiswerecarriedoutforthefailureprocessesofthesteelandconcreteelementsinsideandoutsidethesteel- reinforcedconcretesupportpillars.Andthesimulatedresultswerecomparedwiththeactualblastingresults. Itisshownthatthecommonnodeseparatemodelcandescribetheloadfailuredifferencesbetweensteelandconcreteinthecollapseprocessofthere nforcedconcretestructures.Anditisfeasiblethatthecommonnodeseparatemodelisusedtosimulatethecollapseprocessofthereinforcedconcretestructures
Thedifferencesoftheload-bearingstateandtheintensitywereconsideredbetweensteeland concretewhileastructurecollapsing.Acommonnodeseparatemodelwasadoptedtosimulatethe collapseprocessofareinforcedconcretestructurebyusingthefiniteelementanalysissoftwareANSYS/ LS-DYNA.Aseriesofanalysiswerecarriedoutforthefailureprocessesofthesteelandconcreteelementsinsideandoutsidethesteel- reinforcedconcretesupportpillars.Andthesimulatedresultswerecomparedwiththeactualblastingresults. Itisshownthatthecommonnodeseparatemodelcandescribetheloadfailuredifferencesbetweensteelandconcreteinthecollapseprocessofthere nforcedconcretestructures.Anditisfeasiblethatthecommonnodeseparatemodelisusedtosimulatethecollapseprocessofthereinforcedconcretestructures
Blaststressfieldoflinearexplosivechargeanditsapplication
tomedium-depthholeblastinginundergroundmine
2011, 31(4): 355-360.
doi: 10.11883/1001-1455(2011)04-0355-06
Abstract:
Aimedatthefactthatthetheoreticalguidanceforthesphericalconcentratedchargeblasting haveadiscrepancywiththeactualstatusinthedesignofthemedium-depthholeblasting,twotypes ofexperimentalmodelswereproposed.Modelexperimentswerecarriedoutbyusingholographiclaser dynamicphoto-elasticitytoexploretheexplosionstressfieldsofglobularcharge,andwhichoflinear chargedetonatedatdifferentpoints.Nineorthogonaltests(forty-fourrows)insitewereconductedaboutrowspacing( theminimumresistanceline),holefacedistanceanddetonationpointinborehole toobtainsuitblastingparametersbycombiningtheexperimentalresultsandfineblastingeffectswere got.
Aimedatthefactthatthetheoreticalguidanceforthesphericalconcentratedchargeblasting haveadiscrepancywiththeactualstatusinthedesignofthemedium-depthholeblasting,twotypes ofexperimentalmodelswereproposed.Modelexperimentswerecarriedoutbyusingholographiclaser dynamicphoto-elasticitytoexploretheexplosionstressfieldsofglobularcharge,andwhichoflinear chargedetonatedatdifferentpoints.Nineorthogonaltests(forty-fourrows)insitewereconductedaboutrowspacing( theminimumresistanceline),holefacedistanceanddetonationpointinborehole toobtainsuitblastingparametersbycombiningtheexperimentalresultsandfineblastingeffectswere got.
2011, 31(4): 361-366.
doi: 10.11883/1001-1455(2011)04-0361-06
Abstract:
Aimedatthedifficultyinthetheoreticalanalysisonthemechanicalbehaviorsofaluminum foam-filledcylindricalshellsduetothecomplicatedeformationpatternsofaluminum foamsand shells,theBilkhu/Duboiscrushablefoam modelwasanalyzedandthenusedtodescribethemacroscopicmechanicalbehaviorsofaluminumfoam, randomgeometricimperfectionswereusedtodepict thepotentialimperfectionsofthecylindricalshell,andthestaticanddynamicmechanicalresponsesof thealuminumfoam-filledcylindricalshellsweresimulatedbyFEM.Thenumericalsimulationsarein goodagreementwiththeexperimentaldata.ItshowsthattheBuilhu/Duboiscrushablemodelcanbe usedtodescribethemechanicalbehaviorsofaluminumfoamundercomplexstressesandthenumerical simulationmethodsusedarereasonable.
Aimedatthedifficultyinthetheoreticalanalysisonthemechanicalbehaviorsofaluminum foam-filledcylindricalshellsduetothecomplicatedeformationpatternsofaluminum foamsand shells,theBilkhu/Duboiscrushablefoam modelwasanalyzedandthenusedtodescribethemacroscopicmechanicalbehaviorsofaluminumfoam, randomgeometricimperfectionswereusedtodepict thepotentialimperfectionsofthecylindricalshell,andthestaticanddynamicmechanicalresponsesof thealuminumfoam-filledcylindricalshellsweresimulatedbyFEM.Thenumericalsimulationsarein goodagreementwiththeexperimentaldata.ItshowsthattheBuilhu/Duboiscrushablemodelcanbe usedtodescribethemechanicalbehaviorsofaluminumfoamundercomplexstressesandthenumerical simulationmethodsusedarereasonable.
2011, 31(4): 367-372.
doi: 10.11883/1001-1455(2011)04-0367-06
Abstract:
Aimedatthedifficultiesofunderwaterexplosionloadandinstantaneousfluid-structureinteractioninthenumericalsimulationofdynamicresponseofwarshipstructures, basedontheGeers- Huntermodel,amodifiedmodelforcalculatingtheunderwaterexplosionbubbleloadwasproposed bycombiningwiththeboundaryelementmethod.Toovercometheshortcomingofthesecond-order doubly-asymptoticapproximation(DAA2)methodintreatingthefluid-structureinteractionwithlow frequencyandlargeamplitudemotion,anonlineardoubleasymptoticapproximation(NDAA)method waspresentedbyconsideringthenonlinearfactorssuchastheviolentlow-frequencyresponseofthe warshipanditsfreesurfaceeffect.AndacodewasdevelopedbycombiningthepresentedNDAA methodwiththefiniteelementcodetonumericallyinvestigatethedynamicresponseofwarshipstructuressubjectedtounderwaterexplosionshock avesandbubbles.Themeanerrorbetweennumerical andexperimentalverticalvibrationvelocitiesatthedifferentpositionsisabout16.8%,anditdisplays thatthepresentedNDAA methodisfeasible.
Aimedatthedifficultiesofunderwaterexplosionloadandinstantaneousfluid-structureinteractioninthenumericalsimulationofdynamicresponseofwarshipstructures, basedontheGeers- Huntermodel,amodifiedmodelforcalculatingtheunderwaterexplosionbubbleloadwasproposed bycombiningwiththeboundaryelementmethod.Toovercometheshortcomingofthesecond-order doubly-asymptoticapproximation(DAA2)methodintreatingthefluid-structureinteractionwithlow frequencyandlargeamplitudemotion,anonlineardoubleasymptoticapproximation(NDAA)method waspresentedbyconsideringthenonlinearfactorssuchastheviolentlow-frequencyresponseofthe warshipanditsfreesurfaceeffect.AndacodewasdevelopedbycombiningthepresentedNDAA methodwiththefiniteelementcodetonumericallyinvestigatethedynamicresponseofwarshipstructuressubjectedtounderwaterexplosionshock avesandbubbles.Themeanerrorbetweennumerical andexperimentalverticalvibrationvelocitiesatthedifferentpositionsisabout16.8%,anditdisplays thatthepresentedNDAA methodisfeasible.
2011, 31(4): 373-379.
doi: 10.11883/1001-1455(2011)04-0373-07
Abstract:
Athree-dimensionalsmoothedparticlehydrodynamics(SPH)codewasdevelopedtosimulatethepenetrationofceramic/ metalcompositearmorsbyprojectiles.TheJohnson-CookandJohnson- HolmquistIIconstitutivemodelsandtheMie-Grneisenequationofstatewereincorporatedinto thedevelopedcodetodescribethenonlineardeformationanddamagefeaturesofmetalandceramic materials.Thetypicaldisplacement-timecurvescomputedbythedevelopedSPHcodeareingoodagreementwiththeexperimentalresults. Thenumericalsimulationscanrepresentthemajorfeatures ofthecompositearmorsystem suchas,projectileerosion,ceramicconoidformationandsplash, backingplatefailureandsoon.Andtheobliquityeffectsonthepenetration-resistanceabilityofthe compositearmorwereinvestigated.Theresultsindicatethatthereexistsanoptimalobliquityforthe penetration-resistanceability.
Athree-dimensionalsmoothedparticlehydrodynamics(SPH)codewasdevelopedtosimulatethepenetrationofceramic/ metalcompositearmorsbyprojectiles.TheJohnson-CookandJohnson- HolmquistIIconstitutivemodelsandtheMie-Grneisenequationofstatewereincorporatedinto thedevelopedcodetodescribethenonlineardeformationanddamagefeaturesofmetalandceramic materials.Thetypicaldisplacement-timecurvescomputedbythedevelopedSPHcodeareingoodagreementwiththeexperimentalresults. Thenumericalsimulationscanrepresentthemajorfeatures ofthecompositearmorsystem suchas,projectileerosion,ceramicconoidformationandsplash, backingplatefailureandsoon.Andtheobliquityeffectsonthepenetration-resistanceabilityofthe compositearmorwereinvestigated.Theresultsindicatethatthereexistsanoptimalobliquityforthe penetration-resistanceability.
2011, 31(4): 380-384.
doi: 10.11883/1001-1455(2011)04-0380-05
Abstract:
Themotiondeformationoftheinnershellsoutsidedisperseexplosivewastheoreticallyanalyzed, whichwasresultedfromthedrivingoftheexplosionproduction.Basedonthetheoreticalanalysis, staticexplosiondamagepowerexperimentswereconductedfortwokindsofsingleeventfuelair explosive(SEFAE)deviceswithdifferentstructures,respectively.Experimentalresultsdisplaythat thedamagepowerofthecentrallydispersedSEFAEcanbeimprovedbyaptlydecreasingthestrength oftheinnershells;andthatthedamagepowerofthecentrallyandcircumjacentlydispersedSEFAE canbeimprovedbyproperlyincreasingthestrengthoftheinnershells.
Themotiondeformationoftheinnershellsoutsidedisperseexplosivewastheoreticallyanalyzed, whichwasresultedfromthedrivingoftheexplosionproduction.Basedonthetheoreticalanalysis, staticexplosiondamagepowerexperimentswereconductedfortwokindsofsingleeventfuelair explosive(SEFAE)deviceswithdifferentstructures,respectively.Experimentalresultsdisplaythat thedamagepowerofthecentrallydispersedSEFAEcanbeimprovedbyaptlydecreasingthestrength oftheinnershells;andthatthedamagepowerofthecentrallyandcircumjacentlydispersedSEFAE canbeimprovedbyproperlyincreasingthestrengthoftheinnershells.
2011, 31(4): 385-391.
doi: 10.11883/1001-1455(2011)04-0385-07
Abstract:
Unnotchedoxygen-freehighconductive(OFHC)barsweretestedatdifferenttensilevelocitiesonatensionHopkinsonbarandanovelfacilityforhigh- speedtensiletestsbasedonaone-stage gasgunsystem.AndtheimpactvelocitycorrespondingtothefractureattheimpactendwasdeterminedastheexperimentalcriticalimpactvelocityintensionofOFH .Arepresentativevolumeelement( RVE)wasmodeledbyacircularcylindercontaininganellipsoidvoidatitscenterandtheRVE wasdynamicallyloadedbyanaxialvelocityatitstop.Theentireprocesswasnumericallysimulated fromthevoidgrowthtovoidinstabilityintheRVEforOFHCwhichobeyedtheJ-CorZ-Aconstitutiverelation. Theconditionsofdynamicvoidinstabilitywerediscussedandacriterionbasedonvoid shapeevolutionwaspresented.TheaverageradialstrainsoftheRVEinvoidinstabilitywerecomparedwiththeexperimentallocalizedfracturestrainsoftheunnotchedOFHCbarsu deruniaxialimpacttension. TheexperimentalcriticalimpactvelocityintensionofOFHCwasalsoanalyzedbyusing theRVEmodel.
Unnotchedoxygen-freehighconductive(OFHC)barsweretestedatdifferenttensilevelocitiesonatensionHopkinsonbarandanovelfacilityforhigh- speedtensiletestsbasedonaone-stage gasgunsystem.AndtheimpactvelocitycorrespondingtothefractureattheimpactendwasdeterminedastheexperimentalcriticalimpactvelocityintensionofOFH .Arepresentativevolumeelement( RVE)wasmodeledbyacircularcylindercontaininganellipsoidvoidatitscenterandtheRVE wasdynamicallyloadedbyanaxialvelocityatitstop.Theentireprocesswasnumericallysimulated fromthevoidgrowthtovoidinstabilityintheRVEforOFHCwhichobeyedtheJ-CorZ-Aconstitutiverelation. Theconditionsofdynamicvoidinstabilitywerediscussedandacriterionbasedonvoid shapeevolutionwaspresented.TheaverageradialstrainsoftheRVEinvoidinstabilitywerecomparedwiththeexperimentallocalizedfracturestrainsoftheunnotchedOFHCbarsu deruniaxialimpacttension. TheexperimentalcriticalimpactvelocityintensionofOFHCwasalsoanalyzedbyusing theRVEmodel.
2011, 31(4): 392-396.
doi: 10.11883/1001-1455(2011)04-0392-05
Abstract:
Dynamiccompressiontestsforpolyurethanefoam wereperformedonanelongatedsplit Hopkinsonpressurebarsetup,theincidentbarofwhichwassixmeterlongandthestrikerwaseight decimeterlong.Apulseshaperwasusedtoachievethedynamicbalanceinthestressesatthetwo sidesofthespecimens.About600-microsecondpulseswereexperimentallyobtainedandthestressstraincurvesofpolyurethanefoam wereattainedatthestrainrateof520s-1andthestrainof0.15. Andthediscussionswerecarriedoutfortherelationofstrainrateandstressbalanceatthetwosides ofthespecimens.
Dynamiccompressiontestsforpolyurethanefoam wereperformedonanelongatedsplit Hopkinsonpressurebarsetup,theincidentbarofwhichwassixmeterlongandthestrikerwaseight decimeterlong.Apulseshaperwasusedtoachievethedynamicbalanceinthestressesatthetwo sidesofthespecimens.About600-microsecondpulseswereexperimentallyobtainedandthestressstraincurvesofpolyurethanefoam wereattainedatthestrainrateof520s-1andthestrainof0.15. Andthediscussionswerecarriedoutfortherelationofstrainrateandstressbalanceatthetwosides ofthespecimens.
2011, 31(4): 397-401.
doi: 10.11883/1001-1455(2011)04-0397-05
Abstract:
PressedTNTexplosivewaschosentocarryout2-D Lagrangianexperiments.Therelied two2-Dcompositemanganin-constantan(CMC)LagrangiangaugesatthesameLagrangianposition. Andthetwogaugeswereplacedonandofftheaxis,respectively.ThepressureandradialdisplacementweremeasuredbytheCMCLagrangiangaugesembeddedbetweenindividualdiscsofexplosives. AndtheshockinitiationprocessofthepressedTNTwasanalyzedbyusingthe2-DreactiveflowLagrangiananalysis. AtthedifferentLagrangianpositions,somevariablesweregained,suchasparticle velocity,relativespecificvolume,specificinternalenergy,reactionrateandfrozensoundspeed.Resultsrevealtheeffectsoflateralrarefactionwavesonexplosivevariablesduringshockinitiation.
PressedTNTexplosivewaschosentocarryout2-D Lagrangianexperiments.Therelied two2-Dcompositemanganin-constantan(CMC)LagrangiangaugesatthesameLagrangianposition. Andthetwogaugeswereplacedonandofftheaxis,respectively.ThepressureandradialdisplacementweremeasuredbytheCMCLagrangiangaugesembeddedbetweenindividualdiscsofexplosives. AndtheshockinitiationprocessofthepressedTNTwasanalyzedbyusingthe2-DreactiveflowLagrangiananalysis. AtthedifferentLagrangianpositions,somevariablesweregained,suchasparticle velocity,relativespecificvolume,specificinternalenergy,reactionrateandfrozensoundspeed.Resultsrevealtheeffectsoflateralrarefactionwavesonexplosivevariablesduringshockinitiation.
2011, 31(4): 402-406.
doi: 10.11883/1001-1455(2011)04-0402-05
Abstract:
Toexplorethesplittingstrengthofexpandedpolystyrene(EPS)concretewiththedifferent volumeconcentrationsofEPS,Braziliandiscspecimenswerediametrallyimpactedbyusinga74-mmdiametersplitHopkinsonpressurebar( SHPB)atdifferentimpactvelocities.ForeachvolumeconcentrationofEPS, theBraziliandiscspecimensweretestedinthecasesoftwodifferentparticlesizes ofEPS,respectively.Andaccuratelydesignedcushionswereplacedintheinterspacesbetweentheinputandoutputbarsandthespecimenstopreventthespecimensfrombei gcrushedduetothestress concentrationatthetwoendsofthespecimens.Atthesametime,anappropriatepulseshaperwas usedtoensureenoughtimeforthespecimenstoreachanequilibriumstressstateduringtheexperiment. AndthesplittingfailurepatternsofEPSconcretewereanalyzed.Theresultsdisplaythatthe splittingstrengthofEPSconcreteincreaseswiththeincreaseofstressrate;andthatintheEPSconcretewiththelowvolumeconcentrationofEPS, thesplittingstrengthofEPSconcretetakesonacertainparticlesizeeffect, andthiseffectdisappearsgraduallywiththeincreaseoftheEPSvolumeconcentration.
Toexplorethesplittingstrengthofexpandedpolystyrene(EPS)concretewiththedifferent volumeconcentrationsofEPS,Braziliandiscspecimenswerediametrallyimpactedbyusinga74-mmdiametersplitHopkinsonpressurebar( SHPB)atdifferentimpactvelocities.ForeachvolumeconcentrationofEPS, theBraziliandiscspecimensweretestedinthecasesoftwodifferentparticlesizes ofEPS,respectively.Andaccuratelydesignedcushionswereplacedintheinterspacesbetweentheinputandoutputbarsandthespecimenstopreventthespecimensfrombei gcrushedduetothestress concentrationatthetwoendsofthespecimens.Atthesametime,anappropriatepulseshaperwas usedtoensureenoughtimeforthespecimenstoreachanequilibriumstressstateduringtheexperiment. AndthesplittingfailurepatternsofEPSconcretewereanalyzed.Theresultsdisplaythatthe splittingstrengthofEPSconcreteincreaseswiththeincreaseofstressrate;andthatintheEPSconcretewiththelowvolumeconcentrationofEPS, thesplittingstrengthofEPSconcretetakesonacertainparticlesizeeffect, andthiseffectdisappearsgraduallywiththeincreaseoftheEPSvolumeconcentration.
2011, 31(4): 407-412.
doi: 10.11883/1001-1455(2011)04-0407-06
Abstract:
Basedontheone-stepchemicalreactionEulerequations,thehighresolutionhybridRoe/ HLLschemeandtheadaptivemeshrefinement(AMR)methodwereemployedtonumericallyinvestigatetheprocessofdetonationinducedbythecollisionofthediffractedshockwavesinsideasquare tubewithacubemountedattheaxis.Andtheeffectsofthetubeblockageratioswerediscussedon thedetonationformation.Numericalresultsshowthatwhentheweakshockwavespassaroundthe squareobstruct,boththeupanddownweakshockwavediffractionsoccur,andtheycollidewitheach otherbehindtheobstructafteraperiodofexpansion,ahighpressureandtemperaturepointcanbe generatedduringthecollision,whichcanignitethecombustiblegasesandacceleratetheformationof detonation.However,withalargeblockageratio,astheshockwaveistooweakduringthecollision, thedetonationcannotbeinitiated.
Basedontheone-stepchemicalreactionEulerequations,thehighresolutionhybridRoe/ HLLschemeandtheadaptivemeshrefinement(AMR)methodwereemployedtonumericallyinvestigatetheprocessofdetonationinducedbythecollisionofthediffractedshockwavesinsideasquare tubewithacubemountedattheaxis.Andtheeffectsofthetubeblockageratioswerediscussedon thedetonationformation.Numericalresultsshowthatwhentheweakshockwavespassaroundthe squareobstruct,boththeupanddownweakshockwavediffractionsoccur,andtheycollidewitheach otherbehindtheobstructafteraperiodofexpansion,ahighpressureandtemperaturepointcanbe generatedduringthecollision,whichcanignitethecombustiblegasesandacceleratetheformationof detonation.However,withalargeblockageratio,astheshockwaveistooweakduringthecollision, thedetonationcannotbeinitiated.
2011, 31(4): 413-417.
doi: 10.11883/1001-1455(2011)04-0413-05
Abstract:
Inthispaper,weextendatwo-dimensioncode,whichcouplesanEulerianprogram (SCB scheme)withaLagrangiancode(DEFEL:2-Dfiniteelementcode),tothecontextofmulti-interface scenariobydevelopingaGhost-fluidEuler-Lagrange(GEL)couplingmethod.Weusewater-aironedimensiondualinterfacesRiemmanproblemasacasestudytoevaluatetheproposedmethod. The density,velocityandpressuredistributingareacquired.Andtheexperimentresultsshowthattheisobarictechniqueisabletosignificantlyreducetheinterfaceoverheatingproblem.
Inthispaper,weextendatwo-dimensioncode,whichcouplesanEulerianprogram (SCB scheme)withaLagrangiancode(DEFEL:2-Dfiniteelementcode),tothecontextofmulti-interface scenariobydevelopingaGhost-fluidEuler-Lagrange(GEL)couplingmethod.Weusewater-aironedimensiondualinterfacesRiemmanproblemasacasestudytoevaluatetheproposedmethod. The density,velocityandpressuredistributingareacquired.Andtheexperimentresultsshowthattheisobarictechniqueisabletosignificantlyreducetheinterfaceoverheatingproblem.
2011, 31(4): 418-422.
doi: 10.11883/1001-1455(2011)04-0418-05
Abstract:
Byapplyingthemovingleastsquaresurfacefittingtechniqueandgeneticalgorithmoptimizationtechnology, acompletestructuraloptimizationdesigntechniqueforcrashworthinesswasproposedandthecorrespondingprogramcodesweredevelopedtoreali ethetypicalaircraftstructure crashworthinessoptimizationdesign.Thin-walledcylindricalaluminumtubeswithtriggeringholes weredesignedandproventohavehighefficiencyinenergyabsorption.Theresultsshowthatthis thin-walledcylindricalstructurehasahighenergyabsorptioncapacityanditiseasyinapplication.
Byapplyingthemovingleastsquaresurfacefittingtechniqueandgeneticalgorithmoptimizationtechnology, acompletestructuraloptimizationdesigntechniqueforcrashworthinesswasproposedandthecorrespondingprogramcodesweredevelopedtoreali ethetypicalaircraftstructure crashworthinessoptimizationdesign.Thin-walledcylindricalaluminumtubeswithtriggeringholes weredesignedandproventohavehighefficiencyinenergyabsorption.Theresultsshowthatthis thin-walledcylindricalstructurehasahighenergyabsorptioncapacityanditiseasyinapplication.
2011, 31(4): 423-427.
doi: 10.11883/1001-1455(2011)04-0423-05
Abstract:
Anexplicitexpressionforthestrain-rateeffectontheuniaxialtensilestrengthofbrittlematerialsunderdynamicloadingswasderivedbysolvingthewaveequationtogetherwiththes -calledfinitestructural- timefailurecriterion.Itisshownthatthereisanobviousstructuralresponsecharacteristicforthedynamicstrength; thatis,apartfromonthestrainrateandthestaticmaterialconstants, itdependsremarkablyontheloadingaswellastheinteractionbetweentheloadingfeatures andthematerial,andthusthedynamicstrengthcannotbeoneoftheintrinsicmaterialproperties. Moreover,itisalsofoundthatthepreviousexperimentaldatashouldhaveintrinsicallyhighdiscretenessbecausethedynamicstrengthsofmaterialattaind fferentvaluesunderdifferentloadings.
Anexplicitexpressionforthestrain-rateeffectontheuniaxialtensilestrengthofbrittlematerialsunderdynamicloadingswasderivedbysolvingthewaveequationtogetherwiththes -calledfinitestructural- timefailurecriterion.Itisshownthatthereisanobviousstructuralresponsecharacteristicforthedynamicstrength; thatis,apartfromonthestrainrateandthestaticmaterialconstants, itdependsremarkablyontheloadingaswellastheinteractionbetweentheloadingfeatures andthematerial,andthusthedynamicstrengthcannotbeoneoftheintrinsicmaterialproperties. Moreover,itisalsofoundthatthepreviousexperimentaldatashouldhaveintrinsicallyhighdiscretenessbecausethedynamicstrengthsofmaterialattaind fferentvaluesunderdifferentloadings.
2011, 31(4): 428-432.
doi: 10.11883/1001-1455(2011)04-0428-05
Abstract:
Underwaterexplosionpressuretestandgasbubblepulsationexperimentwereconductedto obtainthetransmissionandattenuationpropertiesaswellasthegasbubblepulsationpropertiesfor theunderwaterexplosionshockwavesofthemetal-claddetonatingcords.Andsomeunderwaterexplosionperformancesforthemetal- claddetonatingcordswereexploredsuchasthesoundpressure level,soundduration,reverberationeffect,andpowerspectrum.Resultsshowthatthemetal-clad detonatingcordsdisplayahighlevelofsoundpressureandsoundpower;thatthegasbubblepulsationsfollowingtheunderwaterexplosionofthemetal- claddetonatingcordsandtheensuinghugeamountofsmallbubbleswillpersistforalongtime, whichcanobservablyincreasethereverberation effectandsounddurationoftheunderwaterexplosion;andthattheunderwaterexplosionsoundofthe metal-claddetonatingcordscoversawiderangeoffrequencies,theenergyineachofwhichispowerful, andtheenergyinthelowfrequencyrangeisthehighest.
Underwaterexplosionpressuretestandgasbubblepulsationexperimentwereconductedto obtainthetransmissionandattenuationpropertiesaswellasthegasbubblepulsationpropertiesfor theunderwaterexplosionshockwavesofthemetal-claddetonatingcords.Andsomeunderwaterexplosionperformancesforthemetal- claddetonatingcordswereexploredsuchasthesoundpressure level,soundduration,reverberationeffect,andpowerspectrum.Resultsshowthatthemetal-clad detonatingcordsdisplayahighlevelofsoundpressureandsoundpower;thatthegasbubblepulsationsfollowingtheunderwaterexplosionofthemetal- claddetonatingcordsandtheensuinghugeamountofsmallbubbleswillpersistforalongtime, whichcanobservablyincreasethereverberation effectandsounddurationoftheunderwaterexplosion;andthattheunderwaterexplosionsoundofthe metal-claddetonatingcordscoversawiderangeoffrequencies,theenergyineachofwhichispowerful, andtheenergyinthelowfrequencyrangeisthehighest.
2011, 31(4): 433-438.
doi: 10.11883/1001-1455(2011)04-0433-06
Abstract:
Aimedatsynthesizingtheencapsulationofnickelnanocrystalwithingraphiticcarbon,effectiveexperimentswerecarriedoutbyadjustingthemoleratioofcarbonsourceandmetalsourcein theseprecursors.Thechemicalcomposition,nanostructuresandmagneticpropertiesofthecomposite particleswereanalyzedbyusingX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM), energydispersiveX-raydetector (EDX)andvibratingsamplemagnetometer (VSM).Theresults showedthatthedifferentsizeandsphericalgraphite-encapsulatednickelnanoparticleswithaperfect core-shellstructurehadbeenpreparedandthatthesemagneticcompositeparticlesmainlydistributed in10-55nm.Themagneticmeasurementsdemonstratedthattheas-preparedCENNPstookonsuperparamagneticorferromagneticbehaviorsatroomtemperature.
Aimedatsynthesizingtheencapsulationofnickelnanocrystalwithingraphiticcarbon,effectiveexperimentswerecarriedoutbyadjustingthemoleratioofcarbonsourceandmetalsourcein theseprecursors.Thechemicalcomposition,nanostructuresandmagneticpropertiesofthecomposite particleswereanalyzedbyusingX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM), energydispersiveX-raydetector (EDX)andvibratingsamplemagnetometer (VSM).Theresults showedthatthedifferentsizeandsphericalgraphite-encapsulatednickelnanoparticleswithaperfect core-shellstructurehadbeenpreparedandthatthesemagneticcompositeparticlesmainlydistributed in10-55nm.Themagneticmeasurementsdemonstratedthattheas-preparedCENNPstookonsuperparamagneticorferromagneticbehaviorsatroomtemperature.
2011, 31(4): 439-443.
doi: 10.11883/1001-1455(2011)04-0439-05
Abstract:
Aimedatthefactthatitisnecessarytodeterminethequantitativerelationbetweenthelocal normaldetonationwavespeedDnandthetotalcurvaturewhendetonationshockdynamics(DSD)is usedtostudynonidealdetonation,steady-statedetonationvelocitiesandwaveshapesweremeasured forHMX/TNTcastexplosivesatmassratios60/40,50/50and40/60.Resultsshowthatdetonation lagzincreaseswiththeincreaseofTNTmasspercentageanditdecreasewiththeincreaseofexplosive density;andthatwiththeincreaseofTNTmasspercentage,theslopesofDn()curvesbecomelarge andthechangeratesoftheslopesarepositive.Forreducingthecostsoftheexperiment,thegeneral Dn(,Rt)lawwasinducedfromtherelationofDn(),andtherelationofRt-z-rwasobtainedbythe Dn(,R t)law.
Aimedatthefactthatitisnecessarytodeterminethequantitativerelationbetweenthelocal normaldetonationwavespeedDnandthetotalcurvaturewhendetonationshockdynamics(DSD)is usedtostudynonidealdetonation,steady-statedetonationvelocitiesandwaveshapesweremeasured forHMX/TNTcastexplosivesatmassratios60/40,50/50and40/60.Resultsshowthatdetonation lagzincreaseswiththeincreaseofTNTmasspercentageanditdecreasewiththeincreaseofexplosive density;andthatwiththeincreaseofTNTmasspercentage,theslopesofDn()curvesbecomelarge andthechangeratesoftheslopesarepositive.Forreducingthecostsoftheexperiment,thegeneral Dn(,Rt)lawwasinducedfromtherelationofDn(),andtherelationofRt-z-rwasobtainedbythe Dn(,R t)law.
2011, 31(4): 444-448.
doi: 10.11883/1001-1455(2011)04-0444-05
Abstract:
Thispaperrevealsthephenomenonoftheaccumulatingenergyeffectofhighvelocityairflowwhichisemergedbyshootingpracticefromaverticalfl ingplateintwinklingofattack.Ingeneralexperimentsofexplosivecompression, theairspaceundertheflyingplateisatmosphericalair,its quantityisalittle,notmorethanonegram.Butinthehighvelocityflingstateoftheflyingplate,the vastmajorityofairisdifficulttoexhausttowardsallaround,atlasttoformtheadiabaticcompression airspurtoutaroundwiththevelocitymorethantenkilometerspersecond,itmaycutoffamuch thicksteelplate.Thisisanunusualexperimentalresultwhichisnotyetnoticedbymajorityofresearchscholars
Thispaperrevealsthephenomenonoftheaccumulatingenergyeffectofhighvelocityairflowwhichisemergedbyshootingpracticefromaverticalfl ingplateintwinklingofattack.Ingeneralexperimentsofexplosivecompression, theairspaceundertheflyingplateisatmosphericalair,its quantityisalittle,notmorethanonegram.Butinthehighvelocityflingstateoftheflyingplate,the vastmajorityofairisdifficulttoexhausttowardsallaround,atlasttoformtheadiabaticcompression airspurtoutaroundwiththevelocitymorethantenkilometerspersecond,itmaycutoffamuch thicksteelplate.Thisisanunusualexperimentalresultwhichisnotyetnoticedbymajorityofresearchscholars
