2011 Vol. 31, No. 3
Display Method:
2011, 31(3): 225-331.
doi: 10.11883/1001-1455(2011)03-0225-07
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Abstract:
Afunctionallylayeredhoneycombmodelisproposedtocontrolthedynamicenergyabsorptionofferedbyuniformhoneycombs. Thein-planedynamicresponsesarecontrolledbythevariation ofthecellradius.Thenumericalresultsshowthatthroughtheproperchoiceofthegradientcoefficient, theinitialforcepeakcanbereducedsignificantly,andtheenergyabsorptioncanbecontrolled. Moreover,thevaluesforthetransmittedstressesintotheprotectedstructurescanbegreatlyreduced. Thesefindingscanprovidevaluablesuggestionsinthemulti-objectiveoptimaldesignofhoneycombs.
Afunctionallylayeredhoneycombmodelisproposedtocontrolthedynamicenergyabsorptionofferedbyuniformhoneycombs. Thein-planedynamicresponsesarecontrolledbythevariation ofthecellradius.Thenumericalresultsshowthatthroughtheproperchoiceofthegradientcoefficient, theinitialforcepeakcanbereducedsignificantly,andtheenergyabsorptioncanbecontrolled. Moreover,thevaluesforthetransmittedstressesintotheprotectedstructurescanbegreatlyreduced. Thesefindingscanprovidevaluablesuggestionsinthemulti-objectiveoptimaldesignofhoneycombs.
2011, 31(3): 232-236.
doi: 10.11883/1001-1455(2011)03-0232-05
Abstract:
AtechniquebasedonluminousfluxmethodwasappliedtomeasureshearstraininSHPSB (splitHopkinsonpressurebar)experiment.Theopticalsetupconsistedofthreemajorcomponents:a collimationlaser,aphotoelectricsensingapparatusandtwoopticalbaffles.Resultsfromavalidexperimentandanuncertaintyanalysisshowedthatitwaseffectiveandaccuratetogettheshearstrain ofthespecimen.Theshearstrainmeasuredbytheopticalapparatuswascomparedwiththetheoretic ones.Itwasfoundandanalyzedthatthemeasuredshearstrainwaslessthanthatofthetheoryinvalue
AtechniquebasedonluminousfluxmethodwasappliedtomeasureshearstraininSHPSB (splitHopkinsonpressurebar)experiment.Theopticalsetupconsistedofthreemajorcomponents:a collimationlaser,aphotoelectricsensingapparatusandtwoopticalbaffles.Resultsfromavalidexperimentandanuncertaintyanalysisshowedthatitwaseffectiveandaccuratetogettheshearstrain ofthespecimen.Theshearstrainmeasuredbytheopticalapparatuswascomparedwiththetheoretic ones.Itwasfoundandanalyzedthatthemeasuredshearstrainwaslessthanthatofthetheoryinvalue
2011, 31(3): 237-242.
doi: 10.11883/1001-1455(2011)03-0237-06
Abstract:
ARMAparameterscanbeusedasfeaturesfordiscriminationbetweennuclearexplosions andearthquakes.Currentmethodsforfeatureextractionarelinearandonlytakesadvantageofthe second-orderstatistic,sotheclassificationaccuracyofisnothigh.Tosolvethisproblem,amethod forextractingnonlinearfeaturesofnuclearexplosionsandearthquakeswasproposedbasedonthechaoticfeatureofseismicwaves. Firstly,thephasespaceofseismicwaveswasreconstructed.Secondly, theadaptivepredictionmodelbasedonVolterraserieswasestablishedinthephasespace.Finally,the modelparametersweretakenasthefeaturesofseismicsamples.Intheclassificationexperimentofof nuclearexplosionsandearthquakes,nonlinearfeaturesobtainedbetterperformancethanlinearfeatures. Investigatedresultsshowthatthecombinationoflinear,nonlinearandhigher-orderstatistical informationiscriticalfortheclassificationofnuclearexplosionsandearthquakes.
ARMAparameterscanbeusedasfeaturesfordiscriminationbetweennuclearexplosions andearthquakes.Currentmethodsforfeatureextractionarelinearandonlytakesadvantageofthe second-orderstatistic,sotheclassificationaccuracyofisnothigh.Tosolvethisproblem,amethod forextractingnonlinearfeaturesofnuclearexplosionsandearthquakeswasproposedbasedonthechaoticfeatureofseismicwaves. Firstly,thephasespaceofseismicwaveswasreconstructed.Secondly, theadaptivepredictionmodelbasedonVolterraserieswasestablishedinthephasespace.Finally,the modelparametersweretakenasthefeaturesofseismicsamples.Intheclassificationexperimentofof nuclearexplosionsandearthquakes,nonlinearfeaturesobtainedbetterperformancethanlinearfeatures. Investigatedresultsshowthatthecombinationoflinear,nonlinearandhigher-orderstatistical informationiscriticalfortheclassificationofnuclearexplosionsandearthquakes.
2011, 31(3): 243-249.
doi: 10.11883/1001-1455(2011)03-0243-07
Abstract:
Thecouplingofsmoothedparticlehydrodynamics(SPH)withthefiniteelementmethod (FEM)ispresentedtomakefulluseofthesuperiorityofSPHindealingwithlargedeformationand thehighaccuracyofFEM.ThecoupledSPH-FEMalgorithmemploysSPHparticlesinthehigherdistortionregionsandfiniteelementsinthelowerdistortionregions. Inthecoupledinterface,SPHparticlesareattachedtofiniteelements. BackgroundparticlesareassignedinthepositionofFEnodes, andFEnodesareaddedtoSPHneighborlist.TheboundaryeffectofSPHisavoided,andthecontinuityoftheinterfaceisguaranteed. Theperforationofacylindricalsteelprojectileimpactingaplate targetissimulatedin3DusingthecoupledSPH-FEMalgorithm.TheJohnson-Cookmaterialmodel withdamageeffectandGrneisenequationofstateareemployedforthetarget,andthecomputedresultsshowgoodagreementwiththeexperimentaldata.
Thecouplingofsmoothedparticlehydrodynamics(SPH)withthefiniteelementmethod (FEM)ispresentedtomakefulluseofthesuperiorityofSPHindealingwithlargedeformationand thehighaccuracyofFEM.ThecoupledSPH-FEMalgorithmemploysSPHparticlesinthehigherdistortionregionsandfiniteelementsinthelowerdistortionregions. Inthecoupledinterface,SPHparticlesareattachedtofiniteelements. BackgroundparticlesareassignedinthepositionofFEnodes, andFEnodesareaddedtoSPHneighborlist.TheboundaryeffectofSPHisavoided,andthecontinuityoftheinterfaceisguaranteed. Theperforationofacylindricalsteelprojectileimpactingaplate targetissimulatedin3DusingthecoupledSPH-FEMalgorithm.TheJohnson-Cookmaterialmodel withdamageeffectandGrneisenequationofstateareemployedforthetarget,andthecomputedresultsshowgoodagreementwiththeexperimentaldata.
2011, 31(3): 250-255.
doi: 10.11883/1001-1455(2011)03-0250-06
Abstract:
TheKelvinimpulseprinciplewasappliedtoanalyzethemajorinfluencefactorsintheformationofthewaterjetbytheinteractionbetweenanunderw terexplosionbubbleandawaterbottom boundary.Andaseriesofexperimentswereconductedinawatertanktoinvestigatethewaterjet phenomenainducedbytheinteractionbetweenbubblesandahorizontallyplacedsteelplate.Thedistancebetweentheexplosiveandthesteelplatewaschangedwiththedifferentexperimentalconditions. Theoscillationpicturesofthewaterjetswerecapturedbyahigh-speedcameraandthepulse pressuresofthebubbleswereobtainedbypressuresensorsatthepositionswiththedifferentdistances awayfromtheexplosionsource.Boththetheoreticalanalysisandtheexperimentalresultsshowthat theBjerknesforceincreasesmarkedlywiththedecreasingdistancebetweentheexplosiveandthesteel plate,andthecriticalcondition,fortheformationofthewaterjetbytheinteractionbetweenthebubbleandthehorizontallyplacedsteelplate, isthattheexplosiondistanceisshorterthanthemaximum bubbleradius.Andthewaterjethasadistinctorientationanditcanremarkablydamagethetarget.
TheKelvinimpulseprinciplewasappliedtoanalyzethemajorinfluencefactorsintheformationofthewaterjetbytheinteractionbetweenanunderw terexplosionbubbleandawaterbottom boundary.Andaseriesofexperimentswereconductedinawatertanktoinvestigatethewaterjet phenomenainducedbytheinteractionbetweenbubblesandahorizontallyplacedsteelplate.Thedistancebetweentheexplosiveandthesteelplatewaschangedwiththedifferentexperimentalconditions. Theoscillationpicturesofthewaterjetswerecapturedbyahigh-speedcameraandthepulse pressuresofthebubbleswereobtainedbypressuresensorsatthepositionswiththedifferentdistances awayfromtheexplosionsource.Boththetheoreticalanalysisandtheexperimentalresultsshowthat theBjerknesforceincreasesmarkedlywiththedecreasingdistancebetweentheexplosiveandthesteel plate,andthecriticalcondition,fortheformationofthewaterjetbytheinteractionbetweenthebubbleandthehorizontallyplacedsteelplate, isthattheexplosiondistanceisshorterthanthemaximum bubbleradius.Andthewaterjethasadistinctorientationanditcanremarkablydamagethetarget.
2011, 31(3): 256-262.
doi: 10.11883/1001-1455(2011)03-0256-07
Abstract:
Anewtechnologyfortestingdynamicpropertiesofmaterialswasproposedbydevelopingan experimentalsetupbasedonasplit-Hopkinsonpressurebarsystem.Theexperimentalsetupcanbe usedindynamicindentationexperimentstoobtaintheindentationdisplacementsofmaterialsandthe impactloadsufferedbythem.Tovalidatetheexperimentalsetup,theABAQUS/ExplicitFEcode wasusedtonumericallysimulatedynamicindentationexperiments.Dynamicindentationexperiments wereconductedonaluminumalloyLY12,puretitaniumandoxygen-freecopper.Thedynamicpropertiessuchasdynamichardnessandratesensitivitywereobtainedforthesethreekindsofmaterials. Thedynamicpropertiesobtainedbydynamicindentationexperimentsareconsistentwiththoseby otherexperimentalmethods.
Anewtechnologyfortestingdynamicpropertiesofmaterialswasproposedbydevelopingan experimentalsetupbasedonasplit-Hopkinsonpressurebarsystem.Theexperimentalsetupcanbe usedindynamicindentationexperimentstoobtaintheindentationdisplacementsofmaterialsandthe impactloadsufferedbythem.Tovalidatetheexperimentalsetup,theABAQUS/ExplicitFEcode wasusedtonumericallysimulatedynamicindentationexperiments.Dynamicindentationexperiments wereconductedonaluminumalloyLY12,puretitaniumandoxygen-freecopper.Thedynamicpropertiessuchasdynamichardnessandratesensitivitywereobtainedforthesethreekindsofmaterials. Thedynamicpropertiesobtainedbydynamicindentationexperimentsareconsistentwiththoseby otherexperimentalmethods.
2011, 31(3): 263-267.
doi: 10.11883/1001-1455(2011)03-0263-05
Abstract:
UnderwaterexplosionexperimentswerecarriedoutforPETNcylindersinawatertankand elementarydataaboutbubblemotionsunderfree-fieldconditionswereobtainedbyusingthehighspeedphotographytechnology. Resultsshowthatthebubbledynamicsofcylindricalchargesdiffers fromthoseofsphericalones,andchargemountingmodesaffectmarkedlybubblebehaviors.Fora horizontallymountedcylindricalcharge,asymmetriccollapseisachievedduetotheasymmetricmotionofthebubbleinterface. Asaresult,anasymmetricjetisformedandthewidthofthejetvaries withthelength-diameterratioofthecharge.Ontheotherhand,foraverticallymountedcylindrical charge,asymmetricjetisgeneratedduetotheaxialsymmetricmotionofthebubbleinterface.Inthe caseofequal-weightcharges,thevelocityofthejetgeneratedbytheverticallymountedcylindrical chargeishigherthanthatgeneratedbythehorizontally-mountedone.
UnderwaterexplosionexperimentswerecarriedoutforPETNcylindersinawatertankand elementarydataaboutbubblemotionsunderfree-fieldconditionswereobtainedbyusingthehighspeedphotographytechnology. Resultsshowthatthebubbledynamicsofcylindricalchargesdiffers fromthoseofsphericalones,andchargemountingmodesaffectmarkedlybubblebehaviors.Fora horizontallymountedcylindricalcharge,asymmetriccollapseisachievedduetotheasymmetricmotionofthebubbleinterface. Asaresult,anasymmetricjetisformedandthewidthofthejetvaries withthelength-diameterratioofthecharge.Ontheotherhand,foraverticallymountedcylindrical charge,asymmetricjetisgeneratedduetotheaxialsymmetricmotionofthebubbleinterface.Inthe caseofequal-weightcharges,thevelocityofthejetgeneratedbytheverticallymountedcylindrical chargeishigherthanthatgeneratedbythehorizontally-mountedone.
2011, 31(3): 268-273.
doi: 10.11883/1001-1455(2011)03-0268-06
Abstract:
Basedona50-mm-diametersplitHopkinsonpressurebar(SHPB)systemandaself-developedconcrete- likematerialrapidheatingdevice,impactcompressiveexperimentswerecarriedout. Thestress-straincurvesatdifferenttemperatureandthreekindsofimpactvelocitieswereobtained. BasedontheZWTvisco-elasticconstitutivemodelanddamageevolutionofcementmortarfollowing Weibulldistribution,thedamagethermo-viscoelasticconstitutiveequationathighstrainrateswas proposed.Throughthenumericalfitting,theparametersoftheconstitutiveequationwereobtained. Comparisonsshowthatthemodelpredictionsagreewellwiththeexperimentresults.
Basedona50-mm-diametersplitHopkinsonpressurebar(SHPB)systemandaself-developedconcrete- likematerialrapidheatingdevice,impactcompressiveexperimentswerecarriedout. Thestress-straincurvesatdifferenttemperatureandthreekindsofimpactvelocitieswereobtained. BasedontheZWTvisco-elasticconstitutivemodelanddamageevolutionofcementmortarfollowing Weibulldistribution,thedamagethermo-viscoelasticconstitutiveequationathighstrainrateswas proposed.Throughthenumericalfitting,theparametersoftheconstitutiveequationwereobtained. Comparisonsshowthatthemodelpredictionsagreewellwiththeexperimentresults.
2011, 31(3): 274-278.
doi: 10.11883/1001-1455(2011)03-0274-05
Abstract:
Aimedatquasi-isentropiccompressionexperiments,abackwardintegrationmodelwasproposedbyconsi- deringlinearelastic-plasticeffects.Thequasi-isentropiccompressionexperimentdata ofRDX(210)crystalfromtheZmachineofSandiaNationalLaboratorywerenumericallyanalyzed. ComparisonbetweenthenumericalresultsandthedatabyBaerM R,etaldisplaysthattheproposed backwardintegration modelcanbeusedtodescribethequasi-isentropiccompressionofRDX(210) crystal.AndthisintegrationmethodwasusedtocalculatetheinformationatanypositionintheRDX (210)sample,especiallyattheloadingsurface,stress-straincurvesandLagrangiansoundvelocities. Thequasi-isentropewasachievedbasedonthemathe-maticsearchprocessofparameters.
Aimedatquasi-isentropiccompressionexperiments,abackwardintegrationmodelwasproposedbyconsi- deringlinearelastic-plasticeffects.Thequasi-isentropiccompressionexperimentdata ofRDX(210)crystalfromtheZmachineofSandiaNationalLaboratorywerenumericallyanalyzed. ComparisonbetweenthenumericalresultsandthedatabyBaerM R,etaldisplaysthattheproposed backwardintegration modelcanbeusedtodescribethequasi-isentropiccompressionofRDX(210) crystal.AndthisintegrationmethodwasusedtocalculatetheinformationatanypositionintheRDX (210)sample,especiallyattheloadingsurface,stress-straincurvesandLagrangiansoundvelocities. Thequasi-isentropewasachievedbasedonthemathe-maticsearchprocessofparameters.
2011, 31(3): 279-284.
doi: 10.11883/1001-1455(2011)03-0279-06
Abstract:
Theengineeringstress-engineeringstrainrelationsofN-1steelweremeasuredusingSHTB atdifferentstrainratesfrom10-3to103s-1.Theresultswereanalyzed,andtherate-hardeninglawof N-1steelwasdetermined.Thetruestressatthecenterofthefracturedcross-sectionwascalculated. Therelationbetweentruestrainandspecimensvaryingthicknesswithinthesmallestcross-section wasexplored,andthetruestrainatthecenterofthefracturedcross-sectionwasidentifiedwitha modifiedapproach.ThusthemodifiedJohnson-Cook (MJC)constitutivemodelparametersofN-1 steelwereidentified.Thebar-barimpacttensileexperimentswithrectangularcross-sectionspecimens werenumericallysimulatedtoverifytheproposedconstitutivemodelparameteridentificationmethod andsimulationmethod.Thesimulatedresultsaresatisfying.
Theengineeringstress-engineeringstrainrelationsofN-1steelweremeasuredusingSHTB atdifferentstrainratesfrom10-3to103s-1.Theresultswereanalyzed,andtherate-hardeninglawof N-1steelwasdetermined.Thetruestressatthecenterofthefracturedcross-sectionwascalculated. Therelationbetweentruestrainandspecimensvaryingthicknesswithinthesmallestcross-section wasexplored,andthetruestrainatthecenterofthefracturedcross-sectionwasidentifiedwitha modifiedapproach.ThusthemodifiedJohnson-Cook (MJC)constitutivemodelparametersofN-1 steelwereidentified.Thebar-barimpacttensileexperimentswithrectangularcross-sectionspecimens werenumericallysimulatedtoverifytheproposedconstitutivemodelparameteridentificationmethod andsimulationmethod.Thesimulatedresultsaresatisfying.
2011, 31(3): 285-289.
doi: 10.11883/1001-1455(2011)03-0285-05
Abstract:
Inordertoinvestigateignitioncharacteristicofenergeticmaterialsradiatedbylaser,agasphasereactionmodelwasestablishedusingdetailedchemicalkinetics. Inthemodel,45speciesand 232reactionstepswasusedtodescribegasphasemechanism.Thenthemodelwasusedformodeling theprocessoflaser-inducedignitionofRDX.Temperaturedistributionsinbothcondensedandgas phasewereobtainedtoanalysetheprocessofignitionofRDX.MoleFractionsofmainspecieswere presentedtoshowthechemicalreactionprocessinthegasphase.Thecalculatedignitiondelaytimes areconsistentwiththeresultsinliteratures.
Inordertoinvestigateignitioncharacteristicofenergeticmaterialsradiatedbylaser,agasphasereactionmodelwasestablishedusingdetailedchemicalkinetics. Inthemodel,45speciesand 232reactionstepswasusedtodescribegasphasemechanism.Thenthemodelwasusedformodeling theprocessoflaser-inducedignitionofRDX.Temperaturedistributionsinbothcondensedandgas phasewereobtainedtoanalysetheprocessofignitionofRDX.MoleFractionsofmainspecieswere presentedtoshowthechemicalreactionprocessinthegasphase.Thecalculatedignitiondelaytimes areconsistentwiththeresultsinliteratures.
2011, 31(3): 290-294.
doi: 10.11883/1001-1455(2011)03-0290-05
Abstract:
Throughthefieldtests,thepropagationregularityofthedirectgroundshockproducedby theexplosionofconventionalchargeatdifferentburieddepthsinfreefieldoflimestonewasexplored. Thedirectgroundshockeffectofexplosionatdifferentburieddepthswasdescribedbytheprocessing engineeringmethodcalledtheburieddepthcoefficientofequivalentenergy.Theburieddepthcoefficientofequivalentenergyofstressandparticleaccelerationofexplosionatdifferentburieddepthsin limestonewereformulated,whichcouldbethepredictionformulaofthegroundshockparametersof explosionatdifferentburieddepthsinlimestonemediaaccordingtothescaleddistancechange.
Throughthefieldtests,thepropagationregularityofthedirectgroundshockproducedby theexplosionofconventionalchargeatdifferentburieddepthsinfreefieldoflimestonewasexplored. Thedirectgroundshockeffectofexplosionatdifferentburieddepthswasdescribedbytheprocessing engineeringmethodcalledtheburieddepthcoefficientofequivalentenergy.Theburieddepthcoefficientofequivalentenergyofstressandparticleaccelerationofexplosionatdifferentburieddepthsin limestonewereformulated,whichcouldbethepredictionformulaofthegroundshockparametersof explosionatdifferentburieddepthsinlimestonemediaaccordingtothescaleddistancechange.
2011, 31(3): 295-299.
doi: 10.11883/1001-1455(2011)03-0295-05
Abstract:
Theunderwaterexplosionmechanismoffluid-structureinteractionwasexploredbasedon thespectralelement.Afieldseparationtechniquewasproposedtoavoidthedistortionphenomenonof thetotalfieldmodelproducedbythepropagationofincidentwaveinthefluidmesh.Andascatteredfieldnumericalmodelforunderwaterexplosionfluid- structurecouplingproblemswasestablishedby theoreticalderivation.Calculationresultsbyaself-developedcodeshowthatthescattered-fieldnumericalmodelisaneffectivesolutiontotheincident- wavedistortion,ithasahighercalculationaccuracythanthetotalfieldmodel, anditcanbeappliedtosolvefluid-solidcouplingproblemsduringunderwaterexplosion.
Theunderwaterexplosionmechanismoffluid-structureinteractionwasexploredbasedon thespectralelement.Afieldseparationtechniquewasproposedtoavoidthedistortionphenomenonof thetotalfieldmodelproducedbythepropagationofincidentwaveinthefluidmesh.Andascatteredfieldnumericalmodelforunderwaterexplosionfluid- structurecouplingproblemswasestablishedby theoreticalderivation.Calculationresultsbyaself-developedcodeshowthatthescattered-fieldnumericalmodelisaneffectivesolutiontotheincident- wavedistortion,ithasahighercalculationaccuracythanthetotalfieldmodel, anditcanbeappliedtosolvefluid-solidcouplingproblemsduringunderwaterexplosion.
2011, 31(3): 300-305.
doi: 10.11883/1001-1455(2011)03-0300-06
Abstract:
Inordertoinvestigatetheexpansioncharacteristicsofthehighpressurecombustiblegasjet inabulk-loadedliquidandtoexplorethecontrolmethodsforimproveingthejetstability,acylindrical four-stagestepped-wallchamberwasdesigned.Usingahigh-speedkinescopesystem,theexpansion andmixingprocessofthegasjetintheliquidwasobserved.Aseriesofphotosdescribingjetexpansionform wereobtained,theexpansionvelocityoftheTaylorcavitywasmeasuredandtheeffectsof thechamberwallshapeonthejetexpansionwerecompared.A2-Daxisymmetricgas-liquidtwo-phase turbulentflow modelwasdevelopedtosimulatethejetexpansionprocess.ThecalculatedjetexpansionshapeandexpansionvelocityoftheTaylorcavitywereconsistentwithexperimentalresults. Obtainedresultsshowthatvortexemergesatthechambersteps, whichinducesthejettoexpandradially thenrestrainsKelvin-Helmholtzinstability.Thestepped-wallchamberboundarycanimprovethejet stability.
Inordertoinvestigatetheexpansioncharacteristicsofthehighpressurecombustiblegasjet inabulk-loadedliquidandtoexplorethecontrolmethodsforimproveingthejetstability,acylindrical four-stagestepped-wallchamberwasdesigned.Usingahigh-speedkinescopesystem,theexpansion andmixingprocessofthegasjetintheliquidwasobserved.Aseriesofphotosdescribingjetexpansionform wereobtained,theexpansionvelocityoftheTaylorcavitywasmeasuredandtheeffectsof thechamberwallshapeonthejetexpansionwerecompared.A2-Daxisymmetricgas-liquidtwo-phase turbulentflow modelwasdevelopedtosimulatethejetexpansionprocess.ThecalculatedjetexpansionshapeandexpansionvelocityoftheTaylorcavitywereconsistentwithexperimentalresults. Obtainedresultsshowthatvortexemergesatthechambersteps, whichinducesthejettoexpandradially thenrestrainsKelvin-Helmholtzinstability.Thestepped-wallchamberboundarycanimprovethejet stability.
2011, 31(3): 306-310.
doi: 10.11883/1001-1455(2011)03-0306-05
Abstract:
Basedonthefactthatinanexperimentaldevicefilledwithexplosiveandfluoride,theexplosionofthecentralexplosivecoulddispersethefluorideoutofthedevice, thenthefluoridewouldintenselyreactwiththeliquidintheconfinedcontainerandreleaseplentifulenergy, threeexperiments withdifferentexplosiondepthswerecarriedoutinsmall-scaleconfinedcontainerstoevaluatethedamagepowerofthisdeviceaccordingtotheoverpressure- impulsecriterion.AndtheTNTequivalent massofthisdevicewascalculated.Theexperimentwiththeexplosiondepthof1.2mwasnumerically simulatedbyusingtheexperimentaldata.Themaximumdispersalvelocityofthetopcoverobtained bysimulationisclosetotheexperimentalresult.Itdisplaysthatthegivenevaluationmethodisfeasible.
Basedonthefactthatinanexperimentaldevicefilledwithexplosiveandfluoride,theexplosionofthecentralexplosivecoulddispersethefluorideoutofthedevice, thenthefluoridewouldintenselyreactwiththeliquidintheconfinedcontainerandreleaseplentifulenergy, threeexperiments withdifferentexplosiondepthswerecarriedoutinsmall-scaleconfinedcontainerstoevaluatethedamagepowerofthisdeviceaccordingtotheoverpressure- impulsecriterion.AndtheTNTequivalent massofthisdevicewascalculated.Theexperimentwiththeexplosiondepthof1.2mwasnumerically simulatedbyusingtheexperimentaldata.Themaximumdispersalvelocityofthetopcoverobtained bysimulationisclosetotheexperimentalresult.Itdisplaysthatthegivenevaluationmethodisfeasible.
2011, 31(3): 311-316.
doi: 10.11883/1001-1455(2011)03-0311-06
Abstract:
Toexploretheinfluenceofthechamberboundaryshapeonthecombustioncontrolina bulk-loadedliquid-mediumelectrothermal-chemicalgun,theplasmajetpropagationintheliquidmediumwasexperimentallyinvestigatedbyusingahigh- speeddigitalcamera.Specialattentionwaspaidto theplasmajet-liquidmediuminteractionundertheconditionsofdifferentdischargevoltages,different nozzlediametersanddifferentdivergentboundaries.Thetime-sequencephotosoftheplasmajetpropagationintheliquidmedium wereobtained,fromthephotostheaxialdisplacementhistoriesofthe Taylorcavitywereachievedunderthedifferentconditions,andthecorrespondingpropagationvelocitiesoftheTaylorcavitywerecalculated. Sequentially,theinteractionmechanismbetweentheplasma jetandtheliquidmediumwasanalyzed.TheresultsindicatethatthoughtheaxialvelocityoftheTaylorcavityisfluctuant, asawholeitisdecrescent;andthatatthewallsteps,theradialturbulenceof theplasmajetisenhanced,whichcanstrengthentheentrainmenteffectofreflux.
Toexploretheinfluenceofthechamberboundaryshapeonthecombustioncontrolina bulk-loadedliquid-mediumelectrothermal-chemicalgun,theplasmajetpropagationintheliquidmediumwasexperimentallyinvestigatedbyusingahigh- speeddigitalcamera.Specialattentionwaspaidto theplasmajet-liquidmediuminteractionundertheconditionsofdifferentdischargevoltages,different nozzlediametersanddifferentdivergentboundaries.Thetime-sequencephotosoftheplasmajetpropagationintheliquidmedium wereobtained,fromthephotostheaxialdisplacementhistoriesofthe Taylorcavitywereachievedunderthedifferentconditions,andthecorrespondingpropagationvelocitiesoftheTaylorcavitywerecalculated. Sequentially,theinteractionmechanismbetweentheplasma jetandtheliquidmediumwasanalyzed.TheresultsindicatethatthoughtheaxialvelocityoftheTaylorcavityisfluctuant, asawholeitisdecrescent;andthatatthewallsteps,theradialturbulenceof theplasmajetisenhanced,whichcanstrengthentheentrainmenteffectofreflux.
2011, 31(3): 317-321.
doi: 10.11883/1001-1455(2011)03-0317-05
Abstract:
Abstract:Bytakingthepulsedischargeswithdifferentcapacitancesastheinputenergy,semiconductorbridges( SCB)withandwithoutleadtrinitroresorcinate(LTNR)wereexperimentallyinvestigated, respectively.Experimentalresultsshowthatthereexistdifferencesinignitionenergy,plasma secondpeakappearancetimeanditsdurationtimeaswellasitspeakvoltagebetweenthetwokindsof SCBs.TheintegralenergyofthebareSCBishigherthanthatoftheSCBwithLTNRatthesamecapacitanceanditchangeslinearlywithcapacitance, buttheintegralenergyoftheSCBwithLTNRis nearlychangeless.ThereasonliesinthefactthattheplasmaofthebareSCBisgeneratedintheair, butforthechargedSCBtheplasmageneratedisusedtoheatLTNRandthenthedecompositionheat ofLTNRcanmaintainthefollowingreaction.Furthermore,theplasmasecondpeakappearanceofthe bareSCBislater,thesecondpeakdurationtimeislonger,andthepeakvoltageofthesecondpeakis lowerthanthoseofthechargedSCBatthesamecapacitance.
Abstract:Bytakingthepulsedischargeswithdifferentcapacitancesastheinputenergy,semiconductorbridges( SCB)withandwithoutleadtrinitroresorcinate(LTNR)wereexperimentallyinvestigated, respectively.Experimentalresultsshowthatthereexistdifferencesinignitionenergy,plasma secondpeakappearancetimeanditsdurationtimeaswellasitspeakvoltagebetweenthetwokindsof SCBs.TheintegralenergyofthebareSCBishigherthanthatoftheSCBwithLTNRatthesamecapacitanceanditchangeslinearlywithcapacitance, buttheintegralenergyoftheSCBwithLTNRis nearlychangeless.ThereasonliesinthefactthattheplasmaofthebareSCBisgeneratedintheair, butforthechargedSCBtheplasmageneratedisusedtoheatLTNRandthenthedecompositionheat ofLTNRcanmaintainthefollowingreaction.Furthermore,theplasmasecondpeakappearanceofthe bareSCBislater,thesecondpeakdurationtimeislonger,andthepeakvoltageofthesecondpeakis lowerthanthoseofthechargedSCBatthesamecapacitance.
2011, 31(3): 322-325.
doi: 10.11883/1001-1455(2011)03-0322-04
Abstract:
Aslideline/erodingalgorithm,whichwasimplementedintothe2DLagrangianelasticityplasticityhydrodynamiccodeLTZ- 2D,wasimproved.Thecellerodingcriterionwaschangedfromthe accumulativeplasticstraintoanintegratedcriterionmadeoftheaccumulativeplasticstrain,thedimensionlessstiffnessfactorandtheangleoppositetheslideline. Andthepenetrationproblemswere numericallysimulatedbytheimprovedalgorithm.Calculatedresultsdisplaythattheimprovedalgorithmcanresolvetheinterfacebetweenthetwoimpactingbodiesandsmoothoutthecurvatureofth slideline.
Aslideline/erodingalgorithm,whichwasimplementedintothe2DLagrangianelasticityplasticityhydrodynamiccodeLTZ- 2D,wasimproved.Thecellerodingcriterionwaschangedfromthe accumulativeplasticstraintoanintegratedcriterionmadeoftheaccumulativeplasticstrain,thedimensionlessstiffnessfactorandtheangleoppositetheslideline. Andthepenetrationproblemswere numericallysimulatedbytheimprovedalgorithm.Calculatedresultsdisplaythattheimprovedalgorithmcanresolvetheinterfacebetweenthetwoimpactingbodiesandsmoothoutthecurvatureofth slideline.
Time-frequencyrepresentationanalysisinunderwaterexplosiveshockwave
signalsbasedonanimprovedHHTmethod
2011, 31(3): 326-331.
doi: 10.11883/1001-1455(2011)03-0326-06
Abstract:
Basedonthecharactersofunderwaterexplosionshockwaves,animprovedHilbert-Huang transform (HHT)methodwasproposedbytakingtheadvantageofHHTinprocessingnon-stationarysignalsandcombiningwaveletdecompositionandcorrelationcoefficientfiltering. Intheimproved HHT method,firstsignalsaredividedintohigh-frequencysignalsandlow-frequencysignalsbywaveletdecomposition, andthenintrinsicmodefunction(IMF)componentsarefilteredbycorrelationcoefficients. Resultsshowthattheimproved HHT methodcanbeappliedtoeffectivelyanalyzethe time-frequencyinformationofunderwaterexplosionshockwavesignals.
Basedonthecharactersofunderwaterexplosionshockwaves,animprovedHilbert-Huang transform (HHT)methodwasproposedbytakingtheadvantageofHHTinprocessingnon-stationarysignalsandcombiningwaveletdecompositionandcorrelationcoefficientfiltering. Intheimproved HHT method,firstsignalsaredividedintohigh-frequencysignalsandlow-frequencysignalsbywaveletdecomposition, andthenintrinsicmodefunction(IMF)componentsarefilteredbycorrelationcoefficients. Resultsshowthattheimproved HHT methodcanbeappliedtoeffectivelyanalyzethe time-frequencyinformationofunderwaterexplosionshockwavesignals.
2011, 31(3): 332-336.
doi: 10.11883/1001-1455(2011)03-0332-05
Abstract:
TheW-Cualloypowderswerepreparedbyhigh-energyball-milling.TheW-Cualloyaslinermaterialswasfabricatedbyexplosiveconsolidation. Theconsolidatedsamplehadatheoreticaldensityof99.6%. ThesamplewasdeterminedbyEPMA,andtheresultsshowedthatthecomposition anddistributionoftheelementswereuniform.ThesamplewasanalyzedbyXRDandtheWcrystallinesizesweremeasuredas26nm. ThesamplewasmachinedintoW-Cualloyliners,showinggood formingproperties.Quietarmor-piercingexperimentoftheW-Cualloylinerofshapedchargewithout aninsulatingboardindicatesthatthearmor-piercingcapabilityincreasesby31.8percentincomparisonwiththecopperliner.
TheW-Cualloypowderswerepreparedbyhigh-energyball-milling.TheW-Cualloyaslinermaterialswasfabricatedbyexplosiveconsolidation. Theconsolidatedsamplehadatheoreticaldensityof99.6%. ThesamplewasdeterminedbyEPMA,andtheresultsshowedthatthecomposition anddistributionoftheelementswereuniform.ThesamplewasanalyzedbyXRDandtheWcrystallinesizesweremeasuredas26nm. ThesamplewasmachinedintoW-Cualloyliners,showinggood formingproperties.Quietarmor-piercingexperimentoftheW-Cualloylinerofshapedchargewithout aninsulatingboardindicatesthatthearmor-piercingcapabilityincreasesby31.8percentincomparisonwiththecopperliner.
