2011 Vol. 31, No. 1
Display Method:
2011, 31(1): 1-5.
doi: 10.11883/1001-1455(2011)01-0001-05
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Abstract:
Experimentshaveshownthatduringtheformationofadiabaticshear,becauseofhighlylocalizeddeformation, theheatgeneratedbyplasticworkcauseslocalizedhightemperatures,andsometimestheprocessmaybeaccompaniedbythephenomenonofdynamicre- crystallization.Basedonthis phenomenon,numericalsimulationsareperformedtosimulateaArnetool-steelbluntnoseprojectile pluggingaWeldox460thintarget,usingthefiniteelementmethod.Theadiabaticshearfailurecriterionisbasedonthehypothesisthatmaterialinsidetheshearbandregionundergoesadynamicre- crystallizationprocess. Numericalsimulationrevealstheadiabaticsheargenerationand propagation process.Thetemperaturedistributionshowsthattheadiabaticshearbandscanprovidephysicalconditionsforadynamicrecrystallizationprocess.
Experimentshaveshownthatduringtheformationofadiabaticshear,becauseofhighlylocalizeddeformation, theheatgeneratedbyplasticworkcauseslocalizedhightemperatures,andsometimestheprocessmaybeaccompaniedbythephenomenonofdynamicre- crystallization.Basedonthis phenomenon,numericalsimulationsareperformedtosimulateaArnetool-steelbluntnoseprojectile pluggingaWeldox460thintarget,usingthefiniteelementmethod.Theadiabaticshearfailurecriterionisbasedonthehypothesisthatmaterialinsidetheshearbandregionundergoesadynamicre- crystallizationprocess. Numericalsimulationrevealstheadiabaticsheargenerationand propagation process.Thetemperaturedistributionshowsthattheadiabaticshearbandscanprovidephysicalconditionsforadynamicrecrystallizationprocess.
2011, 31(1): 6-10.
doi: 10.11883/1001-1455(2011)01-0006-05
Abstract:
Todescribetheinteractionoftheexplosionfieldandthestructure,a2-DEuler-Lagrange couplingmethodwasdevelopedtocoupleaEuleriancodeandaLagrangiancode.TheEulerianfinite differentialcodecalledMMIC(multi-materialsincell)wasusedtosimulatethebehavioroftheexplosionfield. Andthedynamicfiniteelementcodewasusedtocalculatetheresponseofstructures.The Euler-Lagrangecouplingmethodwasusedtosimulatetheprocessofdeformationandpenetrationof anexplosion-drivedfragment.Thenumericalresultsindicatsthatthismethodhastheabilityofsimulatingtheproblemofexplosion- structuresinteration.
Todescribetheinteractionoftheexplosionfieldandthestructure,a2-DEuler-Lagrange couplingmethodwasdevelopedtocoupleaEuleriancodeandaLagrangiancode.TheEulerianfinite differentialcodecalledMMIC(multi-materialsincell)wasusedtosimulatethebehavioroftheexplosionfield. Andthedynamicfiniteelementcodewasusedtocalculatetheresponseofstructures.The Euler-Lagrangecouplingmethodwasusedtosimulatetheprocessofdeformationandpenetrationof anexplosion-drivedfragment.Thenumericalresultsindicatsthatthismethodhastheabilityofsimulatingtheproblemofexplosion- structuresinteration.
2011, 31(1): 11-18.
doi: 10.11883/1001-1455(2011)01-0011-08
Abstract:
Lowvelocityballisticimpactexperimentswerecarriedoutforcompositearmorsystem, whichwascombinedwithcompositelaminatesatthefrontandhomogeneoussteelplatesattheback. Failuremodesandenergyabsorbingmechanism wereanalysed.Ballistic-resistancewascomparedbetweenthecompositelaminatesandhomogeneoussteelplates. Basedontheexperiments,anequation wasobtainedtopredicttheresidualvelocityfortheperforationofcombinedtargetsaccordingtofailuremodes. Resultsshowthattheunitareadensityenergyabsorbingofthecompositelaminatesisfar moregreaterthanthatofhomogenoussteelplates.Failuremodesofthefrontalcompositearmorsof combinedtargetsaremainlyfabrictensilerupture.However,thefailuremodesofthesteelbacking platesaremostlypetalingbecauseoftheinfluenceofthefrontalcompositearmors.Itisshownthat thetheoreticalpredictionsareingoodagreementwithexperimentaldata.
Lowvelocityballisticimpactexperimentswerecarriedoutforcompositearmorsystem, whichwascombinedwithcompositelaminatesatthefrontandhomogeneoussteelplatesattheback. Failuremodesandenergyabsorbingmechanism wereanalysed.Ballistic-resistancewascomparedbetweenthecompositelaminatesandhomogeneoussteelplates. Basedontheexperiments,anequation wasobtainedtopredicttheresidualvelocityfortheperforationofcombinedtargetsaccordingtofailuremodes. Resultsshowthattheunitareadensityenergyabsorbingofthecompositelaminatesisfar moregreaterthanthatofhomogenoussteelplates.Failuremodesofthefrontalcompositearmorsof combinedtargetsaremainlyfabrictensilerupture.However,thefailuremodesofthesteelbacking platesaremostlypetalingbecauseoftheinfluenceofthefrontalcompositearmors.Itisshownthat thetheoreticalpredictionsareingoodagreementwithexperimentaldata.
2011, 31(1): 19-24.
doi: 10.11883/1001-1455(2011)01-0019-06
Abstract:
Thepresentstudyisaimedattheproblemofbulkcavitationfromunderwaterexplosion. Basedonthetheoryofacousticapproximationandconsideredthatthereflectedrarefactivewavecan notspreadthroughbulkcatvitation,theonsetandterminationdepthofbulkcavitaion,thewaterparticlevelocityatvariousinitialdepth, thewaterspallvelocity,thespallclosuredepth,thespallclosuretime, thepeakpressureandthedurationhavebeenobtainedinone-dimensionandtwo-dimensions. Thecontrastbetweentheauthors methodandthe Arons methodshowsthattheupper boudaryofbulkcavitationfromauthorsmethodisidenticalwiththeAronsmethod,andthelower bouderyislessthanAronsatthelocationclosetochargeandmorethanAronsatthelocationapart fromcharge.Acousticapproximationtheorycancalculatetheloadfromclosureofbulkcavitation.
Thepresentstudyisaimedattheproblemofbulkcavitationfromunderwaterexplosion. Basedonthetheoryofacousticapproximationandconsideredthatthereflectedrarefactivewavecan notspreadthroughbulkcatvitation,theonsetandterminationdepthofbulkcavitaion,thewaterparticlevelocityatvariousinitialdepth, thewaterspallvelocity,thespallclosuredepth,thespallclosuretime, thepeakpressureandthedurationhavebeenobtainedinone-dimensionandtwo-dimensions. Thecontrastbetweentheauthors methodandthe Arons methodshowsthattheupper boudaryofbulkcavitationfromauthorsmethodisidenticalwiththeAronsmethod,andthelower bouderyislessthanAronsatthelocationclosetochargeandmorethanAronsatthelocationapart fromcharge.Acousticapproximationtheorycancalculatetheloadfromclosureofbulkcavitation.
2011, 31(1): 25-30.
doi: 10.11883/1001-1455(2011)01-0025-06
Abstract:
Withtheignitionandgrowth model,thematerialpointmethod (MPM)computercode calledMPM-SDT wasdevelopedinFORTRAN90,and wasusedtocomputeshock-to-detonation transitionproblems.TheresultsobtainedbyMPM,traditionalalgorithmsandexperimentwerecompared. Thefeasibilityofusingthematerialpointmethodtosolveshock-to-detonationtransitionproblemswasconfirmed. MPMavoidsthemeshdistortionandtanglingissuesassociatedwithLagrangian methodsandtheadvectionerrorsassociatedwithEulerianmethods.Fragmentsofdifferentmaterial (steel,copper,tungsten,etc.)impactingshieldedexplosiveweresimulated.Theinitiationbehaviour oftungstenisthebest,copperisthesecond,andsteelistheworst.Thecriticaldetonatingvelocityis proportionaltothethicknessofshield.
Withtheignitionandgrowth model,thematerialpointmethod (MPM)computercode calledMPM-SDT wasdevelopedinFORTRAN90,and wasusedtocomputeshock-to-detonation transitionproblems.TheresultsobtainedbyMPM,traditionalalgorithmsandexperimentwerecompared. Thefeasibilityofusingthematerialpointmethodtosolveshock-to-detonationtransitionproblemswasconfirmed. MPMavoidsthemeshdistortionandtanglingissuesassociatedwithLagrangian methodsandtheadvectionerrorsassociatedwithEulerianmethods.Fragmentsofdifferentmaterial (steel,copper,tungsten,etc.)impactingshieldedexplosiveweresimulated.Theinitiationbehaviour oftungstenisthebest,copperisthesecond,andsteelistheworst.Thecriticaldetonatingvelocityis proportionaltothethicknessofshield.
2011, 31(1): 31-35.
doi: 10.11883/1001-1455(2011)01-0031-05
Abstract:
Apolyvinylidenefluoride(PVDF)pressuresensorwasdesignedandtwoequivalentmeasurementcircuitswereintroduced. ThedynamicsensitivityofthePVDFpressuresensorwascalibrated byusingasplitHopkinsonpressurebarsystem.Resultsshowsthatthedynamicsensitivitycoefficientshaveonlysmalldiscrepancyinthecasesofdifferentparallelresistancesandallthecali ration resultsareveryclosetothatgivenbymanufacture.Butthelargertheparallelresistance,thelonger therisetimeofthepulsedthrustgainedbythetestsystem.Obviously,selectingsmallerparallelresistancesisaneffectivewaytoobtainmoreauthenticsignals.
Apolyvinylidenefluoride(PVDF)pressuresensorwasdesignedandtwoequivalentmeasurementcircuitswereintroduced. ThedynamicsensitivityofthePVDFpressuresensorwascalibrated byusingasplitHopkinsonpressurebarsystem.Resultsshowsthatthedynamicsensitivitycoefficientshaveonlysmalldiscrepancyinthecasesofdifferentparallelresistancesandallthecali ration resultsareveryclosetothatgivenbymanufacture.Butthelargertheparallelresistance,thelonger therisetimeofthepulsedthrustgainedbythetestsystem.Obviously,selectingsmallerparallelresistancesisaneffectivewaytoobtainmoreauthenticsignals.
2011, 31(1): 36-42.
doi: 10.11883/1001-1455(2011)01-0036-07
Abstract:
Alaserdisplacementgauge(LDG)systemisproposed.Boththestaticanddynamiccalibrationsarecarriedout, andtheresultsshowthatthesystemiseffectivefordynamictest.Asanefficientmeasuringmethod, theLDGcanbeappliedintheHopkinsonbarexperiment,suchas:(1)the LDGcanbeusedtomonitortheradialdisplacementofthespecimen,withwhichthedynamicPoissonsRatiocanbecalculated;( 2)theLDGcanbeadoptedtomeasurethecracksurfaceopeningdisplacementofthenotchinadynamicfracturetest, andthenthedynamicfractureenergycanbeobtainedbyassociatingthesignalsfromthestraingaugesmountedonthebars;( 3)aninnovativeHopkinsonbarsystemfortestingultra- softmaterialsunderintermediatestrainratesisdeveloped,where theLDGisemployedtomonitorthedeformationofthesampledirectly,andtwopiezoelectricforce transducersaresandwichedbetweenthespecimenandtwobarsrespectivelytomeasuretheweakdynamicloadsdirectly.
Alaserdisplacementgauge(LDG)systemisproposed.Boththestaticanddynamiccalibrationsarecarriedout, andtheresultsshowthatthesystemiseffectivefordynamictest.Asanefficientmeasuringmethod, theLDGcanbeappliedintheHopkinsonbarexperiment,suchas:(1)the LDGcanbeusedtomonitortheradialdisplacementofthespecimen,withwhichthedynamicPoissonsRatiocanbecalculated;( 2)theLDGcanbeadoptedtomeasurethecracksurfaceopeningdisplacementofthenotchinadynamicfracturetest, andthenthedynamicfractureenergycanbeobtainedbyassociatingthesignalsfromthestraingaugesmountedonthebars;( 3)aninnovativeHopkinsonbarsystemfortestingultra- softmaterialsunderintermediatestrainratesisdeveloped,where theLDGisemployedtomonitorthedeformationofthesampledirectly,andtwopiezoelectricforce transducersaresandwichedbetweenthespecimenandtwobarsrespectivelytomeasuretheweakdynamicloadsdirectly.
2011, 31(1): 43-48.
doi: 10.11883/1001-1455(2011)01-0043-06
Abstract:
Bytakingintoaccountthewholeplasticdeformationandelasticdeformationrecoveryoftargetsduringthepenetrationoftherigid, sharp-noseprojectiles,theANSYS/LS-DYNAcodewasused tocalculatethereboundvelocitiesoftheprojectilesandtargetsinthecasesthattheprojectilesatthe samevelocitiespenetratedintothetargetswithdifferentwidthsandthicknesses.Influencesofthesizesofthetargetsandtheimpactvelocitiesoftheprojectilesontheelasticrecoveryofthetargetsand thereboundoftheprojectileswereanalyzed.Theresearchedresultsarehelpfulfortheengineering andexperimentaldesignsoftheprojectileswithlowvelocitiespenetratingintothetargets.
Bytakingintoaccountthewholeplasticdeformationandelasticdeformationrecoveryoftargetsduringthepenetrationoftherigid, sharp-noseprojectiles,theANSYS/LS-DYNAcodewasused tocalculatethereboundvelocitiesoftheprojectilesandtargetsinthecasesthattheprojectilesatthe samevelocitiespenetratedintothetargetswithdifferentwidthsandthicknesses.Influencesofthesizesofthetargetsandtheimpactvelocitiesoftheprojectilesontheelasticrecoveryofthetargetsand thereboundoftheprojectileswereanalyzed.Theresearchedresultsarehelpfulfortheengineering andexperimentaldesignsoftheprojectileswithlowvelocitiespenetratingintothetargets.
2011, 31(1): 49-54.
doi: 10.11883/1001-1455(2011)01-0049-06
Abstract:
ByadoptingtheirrotationalandsteadymotionoftheidealcompressiblefluidandthesupercavitywiththeRiabushinskyschemeofclosure, anintegro-differentialequationwasderivedforthe supercavitatingflowaroundaslendercone-shapedprojectiletravelinginwateratsupersonicspeedby usingtheslender-bodytheoryandthematched-asymptotic-expansionsmethod.Thesecond-orderapproximationsolutionsforthesupercavityprofilesconsideringthecompressibilityeffectwereobtained, andthecalculationprecisionwasimproved.Theinfluencesofthefluidcompressibilityonthesupercavityprofileswereanalyzedunderthehigh- speedimpactofthegun-launchedprojectile.Thefluid compressibilitycausesslightasymmetryofthesupercavityprofile,inwhichtheforwardpartisnarrowerthanthebackwardpart. Becauseofthecompressibilityeffect,when1(Ma) 2,thesupercavityprofilewillexpandsimilarlytothesubsoniccase; thesupercavityprofilewillkeepunchangeable when(Ma) = 2;andthesupercavityprofilewilloccurtoawholecontractionwhen(Ma) 2.
ByadoptingtheirrotationalandsteadymotionoftheidealcompressiblefluidandthesupercavitywiththeRiabushinskyschemeofclosure, anintegro-differentialequationwasderivedforthe supercavitatingflowaroundaslendercone-shapedprojectiletravelinginwateratsupersonicspeedby usingtheslender-bodytheoryandthematched-asymptotic-expansionsmethod.Thesecond-orderapproximationsolutionsforthesupercavityprofilesconsideringthecompressibilityeffectwereobtained, andthecalculationprecisionwasimproved.Theinfluencesofthefluidcompressibilityonthesupercavityprofileswereanalyzedunderthehigh- speedimpactofthegun-launchedprojectile.Thefluid compressibilitycausesslightasymmetryofthesupercavityprofile,inwhichtheforwardpartisnarrowerthanthebackwardpart. Becauseofthecompressibilityeffect,when1(Ma) 2,thesupercavityprofilewillexpandsimilarlytothesubsoniccase; thesupercavityprofilewillkeepunchangeable when(Ma) = 2;andthesupercavityprofilewilloccurtoawholecontractionwhen(Ma) 2.
2011, 31(1): 55-61.
doi: 10.11883/1001-1455(2011)01-0055-07
Abstract:
Asetofprogramsforsolvingelastic-plasticseismicresponseofmultistorymasonrybuildingswaswrittenbyMatlab, whichcombinedNewmarktime-historymethodwithtwo-linearmodelof stiffnessdegradation.Afour-storymasonrybuildingwastakenastheanalyzedobject,andtheactual andartificial-simulatedblastingseismicwaveswereusedastheinputloads,whosecharacteristicparametersweretransformedbasedonacertainprinciple. Accordingtocalculatedresultsofamplitude forallstructuralelastic-plasticseismicresponse,effectsofamplitude,dominantfrequencyanddurationofblastingseismicwavesonelastic- plasticseismicresponseofmultistorymasonrybuildingswere discussedrespectively.Thepresentstudywillprovidetheoreticalandnumericalexperimentfoundationforestablishingmulti- parametersafetycriterionofblastingvibrationandassessingblastingseismiceffectsofbuildingsinblastingzone.
Asetofprogramsforsolvingelastic-plasticseismicresponseofmultistorymasonrybuildingswaswrittenbyMatlab, whichcombinedNewmarktime-historymethodwithtwo-linearmodelof stiffnessdegradation.Afour-storymasonrybuildingwastakenastheanalyzedobject,andtheactual andartificial-simulatedblastingseismicwaveswereusedastheinputloads,whosecharacteristicparametersweretransformedbasedonacertainprinciple. Accordingtocalculatedresultsofamplitude forallstructuralelastic-plasticseismicresponse,effectsofamplitude,dominantfrequencyanddurationofblastingseismicwavesonelastic- plasticseismicresponseofmultistorymasonrybuildingswere discussedrespectively.Thepresentstudywillprovidetheoreticalandnumericalexperimentfoundationforestablishingmulti- parametersafetycriterionofblastingvibrationandassessingblastingseismiceffectsofbuildingsinblastingzone.
2011, 31(1): 62-68.
doi: 10.11883/1001-1455(2011)01-0062-07
Abstract:
Inordertodeterminetheimpactdepthofaconicalprojectileimpactingsinglestiffenedplate vertically,theresidualvelocityoftheprojectileafterpenetratingthestiffenedplatemustbeknown. Theplugisformedaftertheconicalprojectilepenetratingthegrillageandthecrosssectionoftheplug issimilartothatoftheconicalprojectile.Thepetalfailureisformedonthepanel.Bythesqueezeof theconicalprojectile,thewebplateoccursplasticdeformationandthealarplatecausesturnover. Basedonthefailuremodel,theenergyconsumptionmodeofthegrillagewasdetermined.Duringthe perforationprocess,theenergyconsumptionofthegrillagewascompletedbysheardeformationofthe plug,kineticenergyoftheplug,plasticextrudingdeformationofthegrillage,thepowerworkofthe patels,thepropagationofradialcracksandpetalbending.Intheviewofenergy,theenergyformula wasdeducedforeachenergydissipationmodeandtheenergyconsumedintheimpactprocesswasdetermined. Theresidualvelocityandtheballisticlimitvelocityoftheprojectilewasdeducedbyenergy conservationprinciple.Thecomparisonoftheresidualvelocitybetweentheanalyticalandthenumericalresultsisinexcellentagreement, whichverifiestheaccuracyandreliabilityofthetheoreticalformula
Inordertodeterminetheimpactdepthofaconicalprojectileimpactingsinglestiffenedplate vertically,theresidualvelocityoftheprojectileafterpenetratingthestiffenedplatemustbeknown. Theplugisformedaftertheconicalprojectilepenetratingthegrillageandthecrosssectionoftheplug issimilartothatoftheconicalprojectile.Thepetalfailureisformedonthepanel.Bythesqueezeof theconicalprojectile,thewebplateoccursplasticdeformationandthealarplatecausesturnover. Basedonthefailuremodel,theenergyconsumptionmodeofthegrillagewasdetermined.Duringthe perforationprocess,theenergyconsumptionofthegrillagewascompletedbysheardeformationofthe plug,kineticenergyoftheplug,plasticextrudingdeformationofthegrillage,thepowerworkofthe patels,thepropagationofradialcracksandpetalbending.Intheviewofenergy,theenergyformula wasdeducedforeachenergydissipationmodeandtheenergyconsumedintheimpactprocesswasdetermined. Theresidualvelocityandtheballisticlimitvelocityoftheprojectilewasdeducedbyenergy conservationprinciple.Thecomparisonoftheresidualvelocitybetweentheanalyticalandthenumericalresultsisinexcellentagreement, whichverifiestheaccuracyandreliabilityofthetheoreticalformula
2011, 31(1): 69-74.
doi: 10.11883/1001-1455(2011)01-0069-06
Abstract:
Manyinjuriesandfinanciallossareusuallycausedbygasexplosioninlinkedvesselswhen thevesselsandpipescannotbearhighpressureandhighrateofpressurerise.Thehighpressureand rateofpressurerisearemainlyrelatedwiththecharacteristicofgasexplosioninlinkedvessels.Inordertoobtaintheruleandcharacteristicofgasexplosioninlinkedvessels, thetestingsystemforgas explosioninlinkedvesselsisestablished.Theexperimentresultsrevealtheenhancementmechanism ofgasexplosioninlinkedvessels.Theconclusionsprovidedimportantreferenceinengineeringfor safedesignofgasexplosionventinginlinkedvessels.
Manyinjuriesandfinanciallossareusuallycausedbygasexplosioninlinkedvesselswhen thevesselsandpipescannotbearhighpressureandhighrateofpressurerise.Thehighpressureand rateofpressurerisearemainlyrelatedwiththecharacteristicofgasexplosioninlinkedvessels.Inordertoobtaintheruleandcharacteristicofgasexplosioninlinkedvessels, thetestingsystemforgas explosioninlinkedvesselsisestablished.Theexperimentresultsrevealtheenhancementmechanism ofgasexplosioninlinkedvessels.Theconclusionsprovidedimportantreferenceinengineeringfor safedesignofgasexplosionventinginlinkedvessels.
2011, 31(1): 75-80.
doi: 10.11883/1001-1455(2011)01-0075-06
Abstract:
Thepropagationofexplosionstresswavesinstripscontaininganobliqueedgecrackwasanalyzed. Andaseriesofcausticexperimentswereconductedtoexplorethecrackextensionunderblast loading.Investigatedresultsshowthatthecrackgrowthvelocity,accelerationanddynamicstressintensityfactorsfluctuateduringthepropagationoftheobliqueedgecrackunderexplosionstress waves.Themaximumvaluesofthecrackgrowthvelocity,accelerationanddynamicstressintensity factorKdⅠ atthecracktipare222m/s,11.01MN/s2and0.735MN/m3/2,respectively.Thetensile fieldatthetipoftheobliqueedgecrackisamainfactortoinducecrackinitiationandpropagation.
Thepropagationofexplosionstresswavesinstripscontaininganobliqueedgecrackwasanalyzed. Andaseriesofcausticexperimentswereconductedtoexplorethecrackextensionunderblast loading.Investigatedresultsshowthatthecrackgrowthvelocity,accelerationanddynamicstressintensityfactorsfluctuateduringthepropagationoftheobliqueedgecrackunderexplosionstress waves.Themaximumvaluesofthecrackgrowthvelocity,accelerationanddynamicstressintensity factorKdⅠ atthecracktipare222m/s,11.01MN/s2and0.735MN/m3/2,respectively.Thetensile fieldatthetipoftheobliqueedgecrackisamainfactortoinducecrackinitiationandpropagation.
2011, 31(1): 81-87.
doi: 10.11883/1001-1455(2011)01-0081-07
Abstract:
Thequasi-staticanddynamicconstitutiverelationaswellasthefracturemodelof7A04aluminumalloy, fromroomtemperatureto250 ℃,wereinvestigatedbyusingauniversaltestingmachine, atorsiontestingmachineandtheTaylorimpacttest.Basedontheexperimentalresults,the strainhardeningtermoftheJohnson-Cookstrengthmodelandthetemperaturesofteningiteminthe Johnson-Cookfracturemodelweremodified.Thematerialconstantswerecalibratedbyacombination ofexperimentaltestsandnumericalsimulations.Experimentalresultsshowthatboththestrainand strainratehardeningeffectarenotsignificantandthatfracturestrainincreaseswiththeincreaseof temperatureandthedecreaseofeitherstresstriaxialityorstrainrate.
Thequasi-staticanddynamicconstitutiverelationaswellasthefracturemodelof7A04aluminumalloy, fromroomtemperatureto250 ℃,wereinvestigatedbyusingauniversaltestingmachine, atorsiontestingmachineandtheTaylorimpacttest.Basedontheexperimentalresults,the strainhardeningtermoftheJohnson-Cookstrengthmodelandthetemperaturesofteningiteminthe Johnson-Cookfracturemodelweremodified.Thematerialconstantswerecalibratedbyacombination ofexperimentaltestsandnumericalsimulations.Experimentalresultsshowthatboththestrainand strainratehardeningeffectarenotsignificantandthatfracturestrainincreaseswiththeincreaseof temperatureandthedecreaseofeitherstresstriaxialityorstrainrate.
2011, 31(1): 88-94.
doi: 10.11883/1001-1455(2011)01-0088-07
Abstract:
Underwatersoundeffectsgeneratedbytunnel-explosionwerestudiedandanobservation wasperformedtomonitortheunderwatersoundpressureinPseudosciaenacroceasbreedingpond whenGuiyutunnelblastengineeringoccurredthithercoastalharborinLuoyuanCounty,FujianProvince. Basedonacoustictheoryoftransmissionandreflectiononsolid-fluidinterface,theresultsshow thatblastingseismicwave makesimpactonunderwaterenvironmentthroughtwokindsofsound transmittedpaths.Theunderwatersoundintensityincreasessharply(upto150dB)inbreedingpond whenGuiyutunnelblastengineeringoccurs,andtheincrementofsoundintensityisdirectlyproportionaltothemassofexplosivesaswellaswhichisinverselyproportionaltothedistancefro blasting point.However,theeffectofdistanceisgreaterthanthatofmass.Additionally,atdifferenttimeof lowtideandhightide,thesoundintensitygeneratedbyblastingseismicwaveinpondhasasignificant differenceduetothetwopathsofsoundpropagationindifferenttransmittedmedia.Withtheincrementofdistance, soundintensityatlowtidetimedeclinesmorequicklythanthatathightidetime. Similarly,thesoundenergydistributioninfrequencybandhasdifferentshape.Soundathightide timeisdominantinfrequencybandof200~1000Hz.Ontheotherhand,thefrequencyofsoundin pondatlowtidetimeismainlylessthan400Hz.Thegreaterofthewaterdepthaboveseabedis,the lowerofthecut-offlowfrequencyisforunderwateracousticwaveguideeffect.Consequently,thelow tidetimeforGuiyutunnelblastingshouldbechosensothatitcandecreasetheharmofhighintensity inPseudosciaenacroceasbreedingpond,avoidingtodoharmtopseudosciaenacroceasbodyinthe soundresonantfrequencyof500~800Hz.
Underwatersoundeffectsgeneratedbytunnel-explosionwerestudiedandanobservation wasperformedtomonitortheunderwatersoundpressureinPseudosciaenacroceasbreedingpond whenGuiyutunnelblastengineeringoccurredthithercoastalharborinLuoyuanCounty,FujianProvince. Basedonacoustictheoryoftransmissionandreflectiononsolid-fluidinterface,theresultsshow thatblastingseismicwave makesimpactonunderwaterenvironmentthroughtwokindsofsound transmittedpaths.Theunderwatersoundintensityincreasessharply(upto150dB)inbreedingpond whenGuiyutunnelblastengineeringoccurs,andtheincrementofsoundintensityisdirectlyproportionaltothemassofexplosivesaswellaswhichisinverselyproportionaltothedistancefro blasting point.However,theeffectofdistanceisgreaterthanthatofmass.Additionally,atdifferenttimeof lowtideandhightide,thesoundintensitygeneratedbyblastingseismicwaveinpondhasasignificant differenceduetothetwopathsofsoundpropagationindifferenttransmittedmedia.Withtheincrementofdistance, soundintensityatlowtidetimedeclinesmorequicklythanthatathightidetime. Similarly,thesoundenergydistributioninfrequencybandhasdifferentshape.Soundathightide timeisdominantinfrequencybandof200~1000Hz.Ontheotherhand,thefrequencyofsoundin pondatlowtidetimeismainlylessthan400Hz.Thegreaterofthewaterdepthaboveseabedis,the lowerofthecut-offlowfrequencyisforunderwateracousticwaveguideeffect.Consequently,thelow tidetimeforGuiyutunnelblastingshouldbechosensothatitcandecreasetheharmofhighintensity inPseudosciaenacroceasbreedingpond,avoidingtodoharmtopseudosciaenacroceasbodyinthe soundresonantfrequencyof500~800Hz.
2011, 31(1): 95-100.
doi: 10.11883/1001-1455(2011)01-0095-06
Abstract:
Aimedatathin-walledtubestructurewithspecialringsection,combinedwithfiniteelementanalysis, aradial-directionaldynamictensileexperimentalmethodwasproposedbasedonconventionalsplitHopkinsontensilebar( SHTB).Aspecialclampwasdesigned,andahollowsteeltransimissionbarwasusedto magnifythetransmittedsignals.Forthe1Cr18Ni9Tithin-walledtube structure,somedynamictensiletestswereimplementedunderdifferentstrainrates.Theresulsts showthattheexperimentalmethodisapplicabletothethin-walledtubestructurewithspecialring section.Inaddition,thespecialringhasalongplasticstageandthefracturestrainisreducedwith strainrateincressing.Moreover,thetensilestrengthisobviouslyenhancedwithstrainrateincreasing.
Aimedatathin-walledtubestructurewithspecialringsection,combinedwithfiniteelementanalysis, aradial-directionaldynamictensileexperimentalmethodwasproposedbasedonconventionalsplitHopkinsontensilebar( SHTB).Aspecialclampwasdesigned,andahollowsteeltransimissionbarwasusedto magnifythetransmittedsignals.Forthe1Cr18Ni9Tithin-walledtube structure,somedynamictensiletestswereimplementedunderdifferentstrainrates.Theresulsts showthattheexperimentalmethodisapplicabletothethin-walledtubestructurewithspecialring section.Inaddition,thespecialringhasalongplasticstageandthefracturestrainisreducedwith strainrateincressing.Moreover,thetensilestrengthisobviouslyenhancedwithstrainrateincreasing.
2011, 31(1): 101-106.
doi: 10.11883/1001-1455(2011)01-0101-06
Abstract:
Anexperimentalsetupwasdevelopedforrapidheatingupconcretebasedontheprincipleof microwaveheatingandconcretespecimenswere manufactured.Dynamiccompressionexperiments wereconductedforthemanufacturedconcretespecimensbyusingasplitHopkinsonpressurebarsystematdifferenttemperatures. Theexperimentalresultsshowthattemperatureistheprimaryfactor forinfluencingthedynamiccompressionmechanicalperformanceofconcreteathightemperatureand strainrateistheminorfactor.Underdynamiccompression,theconcretedamageathightemperature canbedividedintocrackandfracturemodes.
Anexperimentalsetupwasdevelopedforrapidheatingupconcretebasedontheprincipleof microwaveheatingandconcretespecimenswere manufactured.Dynamiccompressionexperiments wereconductedforthemanufacturedconcretespecimensbyusingasplitHopkinsonpressurebarsystematdifferenttemperatures. Theexperimentalresultsshowthattemperatureistheprimaryfactor forinfluencingthedynamiccompressionmechanicalperformanceofconcreteathightemperatureand strainrateistheminorfactor.Underdynamiccompression,theconcretedamageathightemperature canbedividedintocrackandfracturemodes.
2011, 31(1): 107-112.
doi: 10.11883/1001-1455(2011)01-0107-06
Abstract:
Basedonthestress-straincurvesoffoam-concrete,aconstitutive modeltodescribethe processofporecollapseofporousmaterialisproposed.Thebehaviorofuniaxialstrainwavepropagatedinfoam- concretewasnumericallysimulated,andtheattenuationeffectsofthepeakstressandthe peakenergyofthestresswaveswerestudied.Theresultsshowthatthefoam-concretehasstrongcapabilitytoabsorbthestresswaveinthestageofporecollapse, andthefactorcausedbyporecollapse isthemostimportantandsignificantfactorleadingtothestresswaveattenuation.
Basedonthestress-straincurvesoffoam-concrete,aconstitutive modeltodescribethe processofporecollapseofporousmaterialisproposed.Thebehaviorofuniaxialstrainwavepropagatedinfoam- concretewasnumericallysimulated,andtheattenuationeffectsofthepeakstressandthe peakenergyofthestresswaveswerestudied.Theresultsshowthatthefoam-concretehasstrongcapabilitytoabsorbthestresswaveinthestageofporecollapse, andthefactorcausedbyporecollapse isthemostimportantandsignificantfactorleadingtothestresswaveattenuation.
