2012 Vol. 32, No. 5
Display Method:
2012, 32(5): 449-456.
doi: 10.11883/1001-1455(2012)05-0449-08
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Abstract:
Withfluid-solidcouplingalgorithmbasedonthepenaltyfunctionofnon-lineardynamicfiniteelementprogram ANSYS/LS-DYNA,thedynamicresponseprocessofthethick-walledcylinder subjectedtointernalcylindricalchargeexplosionwasnumericallysimulated.Theevolutionoftheunsteadyblastflowfieldinthecylinderandthedynamicresponseofthecylinderwereanalyzed. Pressurecontourofblastflowfield, thedistributionofblastpressureandimpulseoninnerwallofthecylinder, von-Misesstresscontour,thedistributionofvon-Misesstressweregiven.Simulationresults ofblastpressureandhoopstrainwereingoodagreementwithexperimentalresults,andcalculation resultsofdynamicresponsewerecomparedwiththetheoreticalsolution.Itwasprovedthatthetheoreticalsolutionbasedonplane- strainassumptionmaygiveaconservativeestimateforthisproblem. Theresultsshowthatthethick-walledcylindersubjectedtointernalcylindricalchargeexplosionwas inelasticstate,andthedesignoftheblastchamberissafeincarryingcapacity.Theanalysesarehelpfultosimilardesignandsafeuseofblastchambers.
Withfluid-solidcouplingalgorithmbasedonthepenaltyfunctionofnon-lineardynamicfiniteelementprogram ANSYS/LS-DYNA,thedynamicresponseprocessofthethick-walledcylinder subjectedtointernalcylindricalchargeexplosionwasnumericallysimulated.Theevolutionoftheunsteadyblastflowfieldinthecylinderandthedynamicresponseofthecylinderwereanalyzed. Pressurecontourofblastflowfield, thedistributionofblastpressureandimpulseoninnerwallofthecylinder, von-Misesstresscontour,thedistributionofvon-Misesstressweregiven.Simulationresults ofblastpressureandhoopstrainwereingoodagreementwithexperimentalresults,andcalculation resultsofdynamicresponsewerecomparedwiththetheoreticalsolution.Itwasprovedthatthetheoreticalsolutionbasedonplane- strainassumptionmaygiveaconservativeestimateforthisproblem. Theresultsshowthatthethick-walledcylindersubjectedtointernalcylindricalchargeexplosionwas inelasticstate,andthedesignoftheblastchamberissafeincarryingcapacity.Theanalysesarehelpfultosimilardesignandsafeuseofblastchambers.
2012, 32(5): 457-462.
doi: 10.11883/1001-1455(2012)05-0457-06
Abstract:
Polypropylene(PP)plasticwasreprocessedbylaserfacilitytodecreasethelocalstrengtharoundthescoredline. Theweakenstrengthisnecessarytoevaluatetomeetengineeringrequirement. Inthepresentresearch,thecommercialfiniteelementsoftwareLS-DYNA wasappliedtoanalyze PPsfailurestrengthunderimpact.IntheFE model,theequivalentsectionmethodwasappliedto approximatethetinyorificesformedbylaser.Meanwhile,accountforrate-dependentofPPmaterial, sixstress-straincurveswithdifferentstrainrateweregiventodescribethematerial.Thefailurestrain wasdeterminedthroughparameteridentificationapproach.Comparedwithaseriesofexperiments, thenumericalresultswereconfirmed.Byrangeanalysisofnumericalresults,itwasfoundthatthe failurestrengthincreasedwiththeincreaseofthediameterofseamlessline,anditdecreasedwiththe increaseoftheimpactingvelocity.
Polypropylene(PP)plasticwasreprocessedbylaserfacilitytodecreasethelocalstrengtharoundthescoredline. Theweakenstrengthisnecessarytoevaluatetomeetengineeringrequirement. Inthepresentresearch,thecommercialfiniteelementsoftwareLS-DYNA wasappliedtoanalyze PPsfailurestrengthunderimpact.IntheFE model,theequivalentsectionmethodwasappliedto approximatethetinyorificesformedbylaser.Meanwhile,accountforrate-dependentofPPmaterial, sixstress-straincurveswithdifferentstrainrateweregiventodescribethematerial.Thefailurestrain wasdeterminedthroughparameteridentificationapproach.Comparedwithaseriesofexperiments, thenumericalresultswereconfirmed.Byrangeanalysisofnumericalresults,itwasfoundthatthe failurestrengthincreasedwiththeincreaseofthediameterofseamlessline,anditdecreasedwiththe increaseoftheimpactingvelocity.
2012, 32(5): 463-469.
doi: 10.11883/1001-1455(2012)05-0463-07
Abstract:
BasedonthecomplexvariablefunctionmethodandtheGreensfunctionmethod,thescatteringofSH- wavebyabi-materialinterfacecrackandacircularliningnearabi-materialinterfacein half-spacewasexploredandthecorrespondingdynamicstressconcentrationatthecircularlininginterfacewasinvestigated. Firstly,theexpressionofthescatteringwavewasproposedwhichsatisfiedthe freeboundaryconditions,andthentheGreensfunctionwasconstructed.Secondly,thecrackwas madeoutbythecrack-divisiontechnique,andaseriesofalgebraicequationsfordeterminingtheunknownforcesweredevelopedfromthecontinuityconditions. Finally,someexamplesforthedynamic stressconcentrationfactorsofthecircularelasticliningweregiven,andtheeffectsoftheinterface crack,theincidentwaveandthefreeboundaryonthedynamicstressconcentrationfactorsattheedge ofthecircularelasticinclusionwereanalyzed.Thecalculatedresultsshowthattheexistenceoftheinterfacecrackhasgreateffectsonthedynamicstressconcentrationfactorsatthecircularl ninginterface.
BasedonthecomplexvariablefunctionmethodandtheGreensfunctionmethod,thescatteringofSH- wavebyabi-materialinterfacecrackandacircularliningnearabi-materialinterfacein half-spacewasexploredandthecorrespondingdynamicstressconcentrationatthecircularlininginterfacewasinvestigated. Firstly,theexpressionofthescatteringwavewasproposedwhichsatisfiedthe freeboundaryconditions,andthentheGreensfunctionwasconstructed.Secondly,thecrackwas madeoutbythecrack-divisiontechnique,andaseriesofalgebraicequationsfordeterminingtheunknownforcesweredevelopedfromthecontinuityconditions. Finally,someexamplesforthedynamic stressconcentrationfactorsofthecircularelasticliningweregiven,andtheeffectsoftheinterface crack,theincidentwaveandthefreeboundaryonthedynamicstressconcentrationfactorsattheedge ofthecircularelasticinclusionwereanalyzed.Thecalculatedresultsshowthattheexistenceoftheinterfacecrackhasgreateffectsonthedynamicstressconcentrationfactorsatthecircularl ninginterface.
2012, 32(5): 470-474.
doi: 10.11883/1001-1455(2012)05-0470-05
Abstract:
ByusingthenumericalsimulationsoftwareLS-DYNA,shockdamageprocessesofLY12aluminumalloyplateissimulatedforthefailurecriterionresearch. Theinfluencingfactorssuchasthe peakoverpressure,positivephaseduration,yieldstrengthofmaterial,andnaturalvibrationfrequencyofthestructureareanalyzed. Afailurecriterionbasedontheseparametersispreposedanditagrees withtheexperimentalresults.
ByusingthenumericalsimulationsoftwareLS-DYNA,shockdamageprocessesofLY12aluminumalloyplateissimulatedforthefailurecriterionresearch. Theinfluencingfactorssuchasthe peakoverpressure,positivephaseduration,yieldstrengthofmaterial,andnaturalvibrationfrequencyofthestructureareanalyzed. Afailurecriterionbasedontheseparametersispreposedanditagrees withtheexperimentalresults.
2012, 32(5): 475-482.
doi: 10.11883/1001-1455(2012)05-0475-08
Abstract:
BasedonexplicitdynamicfiniteelementsimulationbyANSYS/LS-DYNA,thein-planedynamiccrushingofhoneycombswithnegativePoissonsratioeffectswasnumericallyinvestigated. Undertheassumptionthattheedgelengthandthicknesswerethesame,thehexagonalhoneycomb modelsfilledwithconcavecellsbythevariationofexpandingangleswereestablished.Theeffectsof expandingangleandimpactvelocityonthein-planecrushingdeformationandenergyabsorptioncapacitiesofhoneycombswerediscussedindetail. Resultsshowthatthein-planedynamiccrushingof re-entranthoneycombsreliesontheexpandingangle.Thelargeristheabsolutevalueoftheexpandingangle, thehigherisplateaustressattheproximalend.Thespecimensdisplayhigherenergyabsorptioncapacitieswiththeincreaseoftheimpactvelocity
BasedonexplicitdynamicfiniteelementsimulationbyANSYS/LS-DYNA,thein-planedynamiccrushingofhoneycombswithnegativePoissonsratioeffectswasnumericallyinvestigated. Undertheassumptionthattheedgelengthandthicknesswerethesame,thehexagonalhoneycomb modelsfilledwithconcavecellsbythevariationofexpandingangleswereestablished.Theeffectsof expandingangleandimpactvelocityonthein-planecrushingdeformationandenergyabsorptioncapacitiesofhoneycombswerediscussedindetail. Resultsshowthatthein-planedynamiccrushingof re-entranthoneycombsreliesontheexpandingangle.Thelargeristheabsolutevalueoftheexpandingangle, thehigherisplateaustressattheproximalend.Thespecimensdisplayhigherenergyabsorptioncapacitieswiththeincreaseoftheimpactvelocity
2012, 32(5): 483-489.
doi: 10.11883/1001-1455(2012)05-0483-07
Abstract:
Thebackgroundofdevelopingthree-stagegasguntechniquedrivenbycompressed-nitrogen forlaunching8km/sprojectileswaspresented.Theeffectsofsubstitutingatwo-stagecompressedgasgun withathree-stagecompressed-gasgunonelevatingprojectilesvelocity werebrieflydescribled. Therelationshipbetweenthedrivingpressure,theinitialpressureofpumptubeandtheload ofthepressurechamberweredissussedforthe57-37-10three-stagegasgun.Someprogressondevelopingthe57- 37-10three-stagegasgunwasshown.
Thebackgroundofdevelopingthree-stagegasguntechniquedrivenbycompressed-nitrogen forlaunching8km/sprojectileswaspresented.Theeffectsofsubstitutingatwo-stagecompressedgasgun withathree-stagecompressed-gasgunonelevatingprojectilesvelocity werebrieflydescribled. Therelationshipbetweenthedrivingpressure,theinitialpressureofpumptubeandtheload ofthepressurechamberweredissussedforthe57-37-10three-stagegasgun.Someprogressondevelopingthe57- 37-10three-stagegasgunwasshown.
2012, 32(5): 490-494.
doi: 10.11883/1001-1455(2012)05-0490-05
Abstract:
Byusingthephotoelectric method,thesteady-statedetonationvelocitiesandthecorrespondingwaveshapesweremeasuredfortheJBO- 9021ratestickswiththediametersof10,15and 30mm,respectively,andintheJBO-9021ratesticksthemassfractionsofTATB,HMXandF2314 were80%,15%and5%,respectively,atroomtemperature.Ananalyticexpressionwasfittedtothe wavefrontdata.Andbasedontheanalyticexpression,therelationwasobtainedbetweenthenormal velocityofthewavefrontanditslocalcurvature.Theinvestigatedresultdisplaysthatthesteady-state detonationvelocityoftheJBO-9021explosiveincreaseswiththeincreaseofthediameteroftheJBO- 9021ratestick.ThedetonationwaveoftheJBO-9021explosiveisfatterthanthatoftheJB-9014explosiveinwhichthemassfractionsofTATBandF2314are95% and5%,respectively.Consequently, thenonidealspreadcharacteristicsofthedetonationwavesweaken.
Byusingthephotoelectric method,thesteady-statedetonationvelocitiesandthecorrespondingwaveshapesweremeasuredfortheJBO- 9021ratestickswiththediametersof10,15and 30mm,respectively,andintheJBO-9021ratesticksthemassfractionsofTATB,HMXandF2314 were80%,15%and5%,respectively,atroomtemperature.Ananalyticexpressionwasfittedtothe wavefrontdata.Andbasedontheanalyticexpression,therelationwasobtainedbetweenthenormal velocityofthewavefrontanditslocalcurvature.Theinvestigatedresultdisplaysthatthesteady-state detonationvelocityoftheJBO-9021explosiveincreaseswiththeincreaseofthediameteroftheJBO- 9021ratestick.ThedetonationwaveoftheJBO-9021explosiveisfatterthanthatoftheJB-9014explosiveinwhichthemassfractionsofTATBandF2314are95% and5%,respectively.Consequently, thenonidealspreadcharacteristicsofthedetonationwavesweaken.
2012, 32(5): 495-500.
doi: 10.11883/1001-1455(2012)05-0495-06
Abstract:
Itisnecessarytodeterminethequantitativerelationbetweenthelocalnormaldetonation wavespeedDnandthetotalcurvaturewhendetonationshockdynamics(DSD)isusedtostudynonidealdetonation. WeextendedourworkontheDn()relationofHMX/TNTratesticksfromthe RDX/TNTratesticks.TheDn()relationofHMX/TNTratesticksinthedifferentmixingratios wasanalyzed,andtheDn ()relation wascomparedbetweentheRDX/TNTexplosivesandthe HMX/TNTexplosives.ResultsshowthattheDn()curvesofRDX/TNTexplosivesweresubjacent ontheDn()curvesofHMX/TNTexplosivesatthesameratio.AstheTNTpercentageadded,the Dn()curvesofRDX/TNTandHMX/TNTexplosivesweremoveddown.TheDn(,Rt)lawwasinducedfromtherelationofDn( )byintroducingintothevariableRt.TheDn(,Rt)lawcouldnotonly reducethenumberofexperimentalcalibration,butalsomeetthesimulationprecisionofDSDmethod.
Itisnecessarytodeterminethequantitativerelationbetweenthelocalnormaldetonation wavespeedDnandthetotalcurvaturewhendetonationshockdynamics(DSD)isusedtostudynonidealdetonation. WeextendedourworkontheDn()relationofHMX/TNTratesticksfromthe RDX/TNTratesticks.TheDn()relationofHMX/TNTratesticksinthedifferentmixingratios wasanalyzed,andtheDn ()relation wascomparedbetweentheRDX/TNTexplosivesandthe HMX/TNTexplosives.ResultsshowthattheDn()curvesofRDX/TNTexplosivesweresubjacent ontheDn()curvesofHMX/TNTexplosivesatthesameratio.AstheTNTpercentageadded,the Dn()curvesofRDX/TNTandHMX/TNTexplosivesweremoveddown.TheDn(,Rt)lawwasinducedfromtherelationofDn( )byintroducingintothevariableRt.TheDn(,Rt)lawcouldnotonly reducethenumberofexperimentalcalibration,butalsomeetthesimulationprecisionofDSDmethod.
2012, 32(5): 501-507.
doi: 10.11883/1001-1455(2012)05-0501-07
Abstract:
StrainrateeffectofconcretedamwastakenintoconsiderationintheestablishmentofgravitydamfullycoupledmodelbyusingsoftwareLS- DYNA.Numericalsimulationmethodwasusedto studythedynamicresponseofthedamsubjectedtostrongunderwaterexplosionshockloading.The possiblefailuremodeandcorrespondingfailuremechanismofconcretegravitydamwerediscussed.It isfoundthatthefailuremodesofdamunderblastloadingdependnotonlyonitsowndynamiccharacteristics, butalsoontheunderwaterdepth,theblastcenterdistanceandthebombdosage.Thehead ofagravitydamisoneofweakpartsforantiknockperformance.Possiblefailuremodesofadamincludeexplosiontopitsatupstreamfaceconcretezoneswhichmeetexplosive, explosion-inducedcollapseatcrestanddownstream, brittlepunchingatjointoftheheadandupstreamplanesandnearthe downstreamslopewithpenetratingcracks.
StrainrateeffectofconcretedamwastakenintoconsiderationintheestablishmentofgravitydamfullycoupledmodelbyusingsoftwareLS- DYNA.Numericalsimulationmethodwasusedto studythedynamicresponseofthedamsubjectedtostrongunderwaterexplosionshockloading.The possiblefailuremodeandcorrespondingfailuremechanismofconcretegravitydamwerediscussed.It isfoundthatthefailuremodesofdamunderblastloadingdependnotonlyonitsowndynamiccharacteristics, butalsoontheunderwaterdepth,theblastcenterdistanceandthebombdosage.Thehead ofagravitydamisoneofweakpartsforantiknockperformance.Possiblefailuremodesofadamincludeexplosiontopitsatupstreamfaceconcretezoneswhichmeetexplosive, explosion-inducedcollapseatcrestanddownstream, brittlepunchingatjointoftheheadandupstreamplanesandnearthe downstreamslopewithpenetratingcracks.
2012, 32(5): 508-514.
doi: 10.11883/1001-1455(2012)05-0508-07
Abstract:
Basedonthethree-dimensionalSPH method,thevariablesmoothinglengthmodificationis appliedtothetraditionallinked-listsearchalgorithm,andthestableapproachofdealingwithmultiphasematerialinterfaceisputforward. Throughsimulatingunderwaterexplosionoffreefield,the feasibilityandeffectivenessofthe modified methodareverified.Thethree-dimensionalnumerical modelisestablished,andtheprocessofunderwaterexplosionnearfreesurfaceisreproduced.Characteristicsofshockwavepropagation, pressurefieldandenergyfieldaresummedup.Theeffectofdifferentexplosiondepthontheinitialwatercolumnformationisstudied. Resultsshowthatfreesurface canattenuatethepeakpressureandimpulsetoonethirdandoneseventhoftheoriginalvalues,respectively. Withtheincreaseofdetonationdepth,curvatureoftheequivalentcylinderofpeakpressureratioandimpulseratiodecrease, andtheproducedwatercolumngraduallytransitsfrombroken andspraycolumntohighandnarrow mound.
Basedonthethree-dimensionalSPH method,thevariablesmoothinglengthmodificationis appliedtothetraditionallinked-listsearchalgorithm,andthestableapproachofdealingwithmultiphasematerialinterfaceisputforward. Throughsimulatingunderwaterexplosionoffreefield,the feasibilityandeffectivenessofthe modified methodareverified.Thethree-dimensionalnumerical modelisestablished,andtheprocessofunderwaterexplosionnearfreesurfaceisreproduced.Characteristicsofshockwavepropagation, pressurefieldandenergyfieldaresummedup.Theeffectofdifferentexplosiondepthontheinitialwatercolumnformationisstudied. Resultsshowthatfreesurface canattenuatethepeakpressureandimpulsetoonethirdandoneseventhoftheoriginalvalues,respectively. Withtheincreaseofdetonationdepth,curvatureoftheequivalentcylinderofpeakpressureratioandimpulseratiodecrease, andtheproducedwatercolumngraduallytransitsfrombroken andspraycolumntohighandnarrow mound.
2012, 32(5): 515-522.
doi: 10.11883/1001-1455(2012)05-0515-08
Abstract:
Inordertoenhancethestructuralstabilityofearthpenetrationwarhead (EPW)inhighspeedpenetration, theadvancedEPW wasdesigned.Theperformanceofthereduced-scaleadvanced EPW wasexperimentallystudiedduringthestrikingvelocitybetween1130~1650m/s.Theresidual projectileswerestudiedbymetallography.Itisfoundthattheheataffectedzone(HAZ)isdistributed aroundtheprojectilesurfacewheretheprojectileandtargetcontact,includingtheprojectilenoseand shank.ThereisnosignificantHAZintheareawheretheprojectileandtargetoffcontact.ItisconcludedthattheinteractionbetweentargetandprojectilebringsHAZin. Ontheotherhand,thereare severaladiabaticshearingbands(ASBs)distributedattheprojectilenosetip.AlthoughASBhaspositivecontributiontotheprojectilemassloss, theinfluencecanbeneglectedduringtheexperimental strikingvelocityrangeduetotherarenumberofASBandthelimiteddistributionarea.However, ASBmayleadtothenonsymmetricalabrasionofpenetratorandthendecreasetheperformanceofprojectileathigherpenetrationvelocity.
Inordertoenhancethestructuralstabilityofearthpenetrationwarhead (EPW)inhighspeedpenetration, theadvancedEPW wasdesigned.Theperformanceofthereduced-scaleadvanced EPW wasexperimentallystudiedduringthestrikingvelocitybetween1130~1650m/s.Theresidual projectileswerestudiedbymetallography.Itisfoundthattheheataffectedzone(HAZ)isdistributed aroundtheprojectilesurfacewheretheprojectileandtargetcontact,includingtheprojectilenoseand shank.ThereisnosignificantHAZintheareawheretheprojectileandtargetoffcontact.ItisconcludedthattheinteractionbetweentargetandprojectilebringsHAZin. Ontheotherhand,thereare severaladiabaticshearingbands(ASBs)distributedattheprojectilenosetip.AlthoughASBhaspositivecontributiontotheprojectilemassloss, theinfluencecanbeneglectedduringtheexperimental strikingvelocityrangeduetotherarenumberofASBandthelimiteddistributionarea.However, ASBmayleadtothenonsymmetricalabrasionofpenetratorandthendecreasetheperformanceofprojectileathigherpenetrationvelocity.
2012, 32(5): 523-527.
doi: 10.11883/1001-1455(2012)05-0523-05
Abstract:
ThecharacteristicofdetonationreactionoftheemulsionexplosivescontainingFe,Mnand Znelementswasdiscussed.Thethermaldecompositioncharacteristicoftheexplosivesanddetonation products,theingredientsandmorphologyofdetonationproductswereallresearchedandcharacterized byDSCandTGexperimentsandXRDandTEMtest.Themostlikelystatusofthesolidproductsin detonationreactionprocesswasalsodiscussedandverifiedbynumericalmethods.Experimentalresultsindicatedthatammonium nitratewashelpfultoform uniform andstabledetonationreaction structurewhichwashelpfultopreparenano-Mn(Zn)ferritepowderswithsameingredientsrepeatably. Thelow-densityexplosiveswereincompletelydetonatedresultinginnano-Mn(Zn)ferritepowderscontaininglotsofimpurities. Thenumericalresultsindicatedthatthephasedistributiondiagram ofthedetonationproductscouldhelpusunderstandthemostlikelystatusofthesoliddetonation productsandMn(Zn)ferritepowdersformationmechanismindetonationreactionprocess.
ThecharacteristicofdetonationreactionoftheemulsionexplosivescontainingFe,Mnand Znelementswasdiscussed.Thethermaldecompositioncharacteristicoftheexplosivesanddetonation products,theingredientsandmorphologyofdetonationproductswereallresearchedandcharacterized byDSCandTGexperimentsandXRDandTEMtest.Themostlikelystatusofthesolidproductsin detonationreactionprocesswasalsodiscussedandverifiedbynumericalmethods.Experimentalresultsindicatedthatammonium nitratewashelpfultoform uniform andstabledetonationreaction structurewhichwashelpfultopreparenano-Mn(Zn)ferritepowderswithsameingredientsrepeatably. Thelow-densityexplosiveswereincompletelydetonatedresultinginnano-Mn(Zn)ferritepowderscontaininglotsofimpurities. Thenumericalresultsindicatedthatthephasedistributiondiagram ofthedetonationproductscouldhelpusunderstandthemostlikelystatusofthesoliddetonation productsandMn(Zn)ferritepowdersformationmechanismindetonationreactionprocess.
2012, 32(5): 528-534.
doi: 10.11883/1001-1455(2012)05-0528-07
Abstract:
The45steelcylindershellswereloadedbytheimprovedSHPBtoundergoexpandingfracture. Theexperimentalcylindershellssubjectedtodifferentdegreesofexpandingdeformationranging fromzerotofracturestrainwererecoveredwithoutsecondloading.Andtheradialstrain,strainrate andcircumferentialtensionstressofthecylindershellsatthefracturepositionwereobtainedbynumericalsimulationandexperiments. Thefracturetime,fracturestrain,fracturestrainrateandfracturestressofthecylindershellsatthefracturepositioncanbeaccuratelydeterminedbythestrainsignalsattheen softhecylindershells.Theimprovedexperimentaltechniquecanbeusedtoobserve theexpandingfractureofthemetalcylindershellsinthestrainraterangefrom102to104s-1.
The45steelcylindershellswereloadedbytheimprovedSHPBtoundergoexpandingfracture. Theexperimentalcylindershellssubjectedtodifferentdegreesofexpandingdeformationranging fromzerotofracturestrainwererecoveredwithoutsecondloading.Andtheradialstrain,strainrate andcircumferentialtensionstressofthecylindershellsatthefracturepositionwereobtainedbynumericalsimulationandexperiments. Thefracturetime,fracturestrain,fracturestrainrateandfracturestressofthecylindershellsatthefracturepositioncanbeaccuratelydeterminedbythestrainsignalsattheen softhecylindershells.Theimprovedexperimentaltechniquecanbeusedtoobserve theexpandingfractureofthemetalcylindershellsinthestrainraterangefrom102to104s-1.
2012, 32(5): 535-541.
doi: 10.11883/1001-1455(2012)05-0535-07
Abstract:
Theshort-timeFouriertransformcannotmeetthedifferentrequirementsofthehighand lowfrequencychangesofsignalandthewavelettransformcanbelimitedbythewaveletbaseweselect. Therefore,weuse HHTtoanalysetheblastingvibrationsignalthroughthetime-frequency powerspectrum.IntheEMD,weusethesymmetricextendingofextremepointtoeliminatethe effectofendpoint.WeusethepiecewisecubicHermiteinterpolatingtoeliminatethephenomenondue totheenvelope,andadoptthelocalcriterionofsiftingtermination.Fortheproblemofnegativepeak incalculatingtheinstantaneousfrequencyinthetraditionalHilberttransform,weadoptthenormalizedHilbertandthedirectquadraturemethodtosolve. InalltheHHTanalysis,weusetheLabView platformtoachievewhichcanimprovecomputingefficiencyandpracticality,andweprovethatHHT isusefulfortheanalysisoftheblastingvibrationsignal.
Theshort-timeFouriertransformcannotmeetthedifferentrequirementsofthehighand lowfrequencychangesofsignalandthewavelettransformcanbelimitedbythewaveletbaseweselect. Therefore,weuse HHTtoanalysetheblastingvibrationsignalthroughthetime-frequency powerspectrum.IntheEMD,weusethesymmetricextendingofextremepointtoeliminatethe effectofendpoint.WeusethepiecewisecubicHermiteinterpolatingtoeliminatethephenomenondue totheenvelope,andadoptthelocalcriterionofsiftingtermination.Fortheproblemofnegativepeak incalculatingtheinstantaneousfrequencyinthetraditionalHilberttransform,weadoptthenormalizedHilbertandthedirectquadraturemethodtosolve. InalltheHHTanalysis,weusetheLabView platformtoachievewhichcanimprovecomputingefficiencyandpracticality,andweprovethatHHT isusefulfortheanalysisoftheblastingvibrationsignal.
2012, 32(5): 542-546.
doi: 10.11883/1001-1455(2012)05-0542-05
Abstract:
Newequipmentwhichcoulddriveaplanarflyerviathenetworkdetonationtechniqueto generatelowimpactstressandlowimpactvelocitywasdesigned.Thevelocityandplanarityofthe flyerandtheotherequipmentparameterswereanalyzedbyusingexperimentalmeasurementandnumericalsimulation. Resultsindicatethattheequipmentcoulddrivethehigh-purityOFHCflyerwith 100-mmdiameterand3-mmthicknessapproachingastablevelocityafterabout2mmflight.Thevelocityoftheflyeriscontinuouslyadjustablefromabout200to350m/ swithgoodplanarityanduniformity. Thenetworkdetonation-loadingmethodcanbeusedtolaunchaflyerplateatlowvelocity.
Newequipmentwhichcoulddriveaplanarflyerviathenetworkdetonationtechniqueto generatelowimpactstressandlowimpactvelocitywasdesigned.Thevelocityandplanarityofthe flyerandtheotherequipmentparameterswereanalyzedbyusingexperimentalmeasurementandnumericalsimulation. Resultsindicatethattheequipmentcoulddrivethehigh-purityOFHCflyerwith 100-mmdiameterand3-mmthicknessapproachingastablevelocityafterabout2mmflight.Thevelocityoftheflyeriscontinuouslyadjustablefromabout200to350m/ swithgoodplanarityanduniformity. Thenetworkdetonation-loadingmethodcanbeusedtolaunchaflyerplateatlowvelocity.
2012, 32(5): 547-550.
doi: 10.11883/1001-1455(2012)05-0547-04
Abstract:
Technologyofmagneticallydrivenflyertohighvelocityhasbeendevelopedquicklyinrecent years,especiallyatSandialaboratory.Thedesignoftheflyersizeispresentedtheoreticallyandnumerically. Theminimum widthoftheflyerisgivenbyanequationconsideringtheinfluenceofrarefactionwavefromflyerside. Theflyerlengthismainlylimitedbytheconductance.Theflyerthicknessisdecidedbythemagneticfielddiffusionandthemagnitudeofdrivencurrent
Technologyofmagneticallydrivenflyertohighvelocityhasbeendevelopedquicklyinrecent years,especiallyatSandialaboratory.Thedesignoftheflyersizeispresentedtheoreticallyandnumerically. Theminimum widthoftheflyerisgivenbyanequationconsideringtheinfluenceofrarefactionwavefromflyerside. Theflyerlengthismainlylimitedbytheconductance.Theflyerthicknessisdecidedbythemagneticfielddiffusionandthemagnitudeofdrivencurrent
2012, 32(5): 551-556.
doi: 10.11883/1001-1455(2012)05-0551-06
Abstract:
Afullycouplednumericalanalysistechnologyisusedtosimulatetheresponseofalargescaleboxculvertunderblastload, inwhichSPH methodisadoptedtomodelthenearfieldmedium, whileFEMisusedtomodelthefarfieldsoilandreinforcedconcreteboxculvert.Theresultsshow thatthedamagepositionanddegreearecloselyrelatedtochargerelativepositiontoboxculvert. Thereisanobviousdifferenceamongstressanddeformationofboxculvertunderdifferentdetonation. Especiallyatthecenterpositionofthewall,thereisanobviouseffectofsoilflowonreloadand changeofstressunderdifferentdetonation.ThefinalconclusionshowthatthecoupledSPH-FEanalysistechnologycansatisfycalculationefficiencyandengineeringrequirements.
Afullycouplednumericalanalysistechnologyisusedtosimulatetheresponseofalargescaleboxculvertunderblastload, inwhichSPH methodisadoptedtomodelthenearfieldmedium, whileFEMisusedtomodelthefarfieldsoilandreinforcedconcreteboxculvert.Theresultsshow thatthedamagepositionanddegreearecloselyrelatedtochargerelativepositiontoboxculvert. Thereisanobviousdifferenceamongstressanddeformationofboxculvertunderdifferentdetonation. Especiallyatthecenterpositionofthewall,thereisanobviouseffectofsoilflowonreloadand changeofstressunderdifferentdetonation.ThefinalconclusionshowthatthecoupledSPH-FEanalysistechnologycansatisfycalculationefficiencyandengineeringrequirements.
2012, 32(5): 557-560.
doi: 10.11883/1001-1455(2012)05-0557-04
Abstract:
Accordingtothestresswavetheory,thebufferandshockabsorptionstructureofadatarecorderwasdesignedbyconsideringthereasonableallocationofthegeneralizedimpedancerat o.The compositestructureforshockabsorptionwasdesignedtosolvetheproblemofnarrowspaceimpact protection.AndtheoptimizationwascarriedoutbycombiningIsightandLs-dynatoreducethedynamicstressoftheprotectedcomponentratherthantheimpactacceleration. Asaresult,thedynamic stressoftheprotectedcomponentdecreasesbyabout70.9%andthemassofthedatarecorderreduces 300gram.Intheend,thebombardmenttestwasperformedandthedatawererecoveredsuccessfully.
Accordingtothestresswavetheory,thebufferandshockabsorptionstructureofadatarecorderwasdesignedbyconsideringthereasonableallocationofthegeneralizedimpedancerat o.The compositestructureforshockabsorptionwasdesignedtosolvetheproblemofnarrowspaceimpact protection.AndtheoptimizationwascarriedoutbycombiningIsightandLs-dynatoreducethedynamicstressoftheprotectedcomponentratherthantheimpactacceleration. Asaresult,thedynamic stressoftheprotectedcomponentdecreasesbyabout70.9%andthemassofthedatarecorderreduces 300gram.Intheend,thebombardmenttestwasperformedandthedatawererecoveredsuccessfully.
