2010 Vol. 30, No. 5
Display Method:
2010, 30(5): 449-455.
doi: 10.11883/1001-1455(2010)05-0449-07
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Abstract:
Thetensilestress-straincurvesofporcineham musclealongthelongitudinalandtransverse directionsofthemusclefibrewereobtainedoverawiderangeofstrainrates(0.02~2100s-1).The experimentswereperformedbyusingthebiomechanicaltestingsystemandthepolymericsplitHopkinsontensilebar( SHTB)inthetubes.Aprogram wascompiledtomodifytheeffectofdispersion andattenuationofwavesintheviscoelasticpolymericbarusedasthetransmissionbarinthedynamic experiments.Statisticalanalysesweredonebyusingone-wayANOVA (p0.05).Theresultsshow thattheflowstressoftheporcineham muscleatthehighstrainrateof2100s-1isbothapparently higherthanthatatthelowstrainrateof0.02s-1alongthetwoloadingdirections,illustratingthe strainratesensitivitiesoftheporcineham muscle.Atthelowstrainrates,theultimatestrengthsalongthelongitudinaldirectionarehigherthanthosealongthetransversedirection, whereasthereare nosignificantdifferencesbetweentheirfailurestrainvalues.Thequasi-staticstress-straincurvesbehaveastheothersofttissues, exhibitinganinitialnon-lineartoeregion,followedbyalinearregion andsubsequentlyanonlinearregionpriortothegradualfailure.Atthehighstrainrates,thetoeregionvanishesbecauseithasnoenoughtimetopermitthestraighteningofthehelicalstructure. The initialmodulusinthetransversedirectionismuchhigherthanthatinthelongitudinaldirection.However, whenthestrainincreases,theflowstressesinthetwodirectionshavenosignificantdifference andtheflowstressinthelongitudinaldirectiongraduallyinclinestohigherthanthatinthetransverse direction.
Thetensilestress-straincurvesofporcineham musclealongthelongitudinalandtransverse directionsofthemusclefibrewereobtainedoverawiderangeofstrainrates(0.02~2100s-1).The experimentswereperformedbyusingthebiomechanicaltestingsystemandthepolymericsplitHopkinsontensilebar( SHTB)inthetubes.Aprogram wascompiledtomodifytheeffectofdispersion andattenuationofwavesintheviscoelasticpolymericbarusedasthetransmissionbarinthedynamic experiments.Statisticalanalysesweredonebyusingone-wayANOVA (p0.05).Theresultsshow thattheflowstressoftheporcineham muscleatthehighstrainrateof2100s-1isbothapparently higherthanthatatthelowstrainrateof0.02s-1alongthetwoloadingdirections,illustratingthe strainratesensitivitiesoftheporcineham muscle.Atthelowstrainrates,theultimatestrengthsalongthelongitudinaldirectionarehigherthanthosealongthetransversedirection, whereasthereare nosignificantdifferencesbetweentheirfailurestrainvalues.Thequasi-staticstress-straincurvesbehaveastheothersofttissues, exhibitinganinitialnon-lineartoeregion,followedbyalinearregion andsubsequentlyanonlinearregionpriortothegradualfailure.Atthehighstrainrates,thetoeregionvanishesbecauseithasnoenoughtimetopermitthestraighteningofthehelicalstructure. The initialmodulusinthetransversedirectionismuchhigherthanthatinthelongitudinaldirection.However, whenthestrainincreases,theflowstressesinthetwodirectionshavenosignificantdifference andtheflowstressinthelongitudinaldirectiongraduallyinclinestohigherthanthatinthetransverse direction.
2010, 30(5): 456-462.
doi: 10.11883/1001-1455(2010)05-0456-07
Abstract:
Basedonanactualtunnelexcavationproject,thethree-dimensionalfiniteelementmodelof tunnelexcavationwassetup,andtheparticlevibrationandstressdistributionwereanalyzedatthe existingadjacenttunnelconcretelining.Thecalculationresultshowsthatinthewholerangeofinvestigation, theverticalpeakparticlevibrationisbiggerthanthoseintheothertwodirections,butthe maintensilestressinthetunnelvaultcrownandbottomisinthehorizontaldirection,whichproves thattheverticalpeakparticlevibrationcannottotallyrepresentthestressstateofrock.Inactualprojects, theblastingpeakparticlevibrationshouldbecontrolled,andthestressstateofrockshouldbe analyzedaswell.Themaximumpeakparticlevibrationcalculatedis4.94cm/s,whichissmallerthan 5.00cm/srequiredinprojects;themaximumtensilestressinthetunnelvaultcrownis0.54MPa,so thetunnelconcretelineisnotaffected.
Basedonanactualtunnelexcavationproject,thethree-dimensionalfiniteelementmodelof tunnelexcavationwassetup,andtheparticlevibrationandstressdistributionwereanalyzedatthe existingadjacenttunnelconcretelining.Thecalculationresultshowsthatinthewholerangeofinvestigation, theverticalpeakparticlevibrationisbiggerthanthoseintheothertwodirections,butthe maintensilestressinthetunnelvaultcrownandbottomisinthehorizontaldirection,whichproves thattheverticalpeakparticlevibrationcannottotallyrepresentthestressstateofrock.Inactualprojects, theblastingpeakparticlevibrationshouldbecontrolled,andthestressstateofrockshouldbe analyzedaswell.Themaximumpeakparticlevibrationcalculatedis4.94cm/s,whichissmallerthan 5.00cm/srequiredinprojects;themaximumtensilestressinthetunnelvaultcrownis0.54MPa,so thetunnelconcretelineisnotaffected.
2010, 30(5): 463-471.
doi: 10.11883/1001-1455(2010)05-0463-09
Abstract:
ParametersoftheJohnson-Holmquistconstitutivemodel(JH-2)weredeterminedforAl2O3 ceramicfromtheexistingliteraturedatabyusingacombinationmethodofexperimentalandnumerical techniques.BasedonthisJH-2modelcontainingdamage,anexplicitfiniteelementanalysiscodeLSDYNA wasappliedtosimulatethedamagemechanismandfragmentationprocessoftheAl2O3ceramicsubjectedtolow- velocityimpactinaSHPBsystem.Theresultsofthisworkmaybesummarizedas follows:Underdynamiccompression,Al2O3ceramicmainlytakesonaxialsplitdamage;Theshorter theloadingtimeoftheincidentcompressionwave,themoreseriouslythespecimensarefragmented; ThespecimenfragmentationmodessimulatedbytheJH-2modelareinagreementwiththoseofthe recoveredspecimensinSHPBtest.
ParametersoftheJohnson-Holmquistconstitutivemodel(JH-2)weredeterminedforAl2O3 ceramicfromtheexistingliteraturedatabyusingacombinationmethodofexperimentalandnumerical techniques.BasedonthisJH-2modelcontainingdamage,anexplicitfiniteelementanalysiscodeLSDYNA wasappliedtosimulatethedamagemechanismandfragmentationprocessoftheAl2O3ceramicsubjectedtolow- velocityimpactinaSHPBsystem.Theresultsofthisworkmaybesummarizedas follows:Underdynamiccompression,Al2O3ceramicmainlytakesonaxialsplitdamage;Theshorter theloadingtimeoftheincidentcompressionwave,themoreseriouslythespecimensarefragmented; ThespecimenfragmentationmodessimulatedbytheJH-2modelareinagreementwiththoseofthe recoveredspecimensinSHPBtest.
2010, 30(5): 472-478.
doi: 10.11883/1001-1455(2010)05-0472-07
Abstract:
Toachievethatadynamitesourceshouldprovidehighseismicenergywithoutdestroyingthe oilwellinthereversedverticalseismicprofile(RVSP)prospectingofpetroleum,theoreticalanalysis wascarriedoutfortheenergytransferofthedynamitesourceandfiniteelementmodelsweredevelopedforthedynamitesourceanditssurroundingme iaintheoilwell.Numericalsimulationswere conductedbyapplyingtheAUTODYN-2Dsoftwaretoexploretheinteractionbetweentheoilwelland thedynamitesource.Thevibrationvelocityandpressurecurveswereobtainedfortheparticlelocated 10mawayfromtheseismicsourcetoinvestigatetheinfluencesofthemediaintheoilwellontheenergytransferofthedynamitesource. Effectsofthechargediametersonthedeformationoftheoil wellpipewereanalyzed.Andsomediscussionwasmadeontheeffectsofthechargelengthontheenergytransferofthedynamitesourceandthedeformationoftheoilwellpipe. Thecorrespondingexperimentwasimplementedtocomparewiththenumericalresults. Thenumericalresultsareconsistentwiththeexperimentalobservations. Theresearchcanprovidehelpfortheengineeringapplication oftheRVSPprospecting.
Toachievethatadynamitesourceshouldprovidehighseismicenergywithoutdestroyingthe oilwellinthereversedverticalseismicprofile(RVSP)prospectingofpetroleum,theoreticalanalysis wascarriedoutfortheenergytransferofthedynamitesourceandfiniteelementmodelsweredevelopedforthedynamitesourceanditssurroundingme iaintheoilwell.Numericalsimulationswere conductedbyapplyingtheAUTODYN-2Dsoftwaretoexploretheinteractionbetweentheoilwelland thedynamitesource.Thevibrationvelocityandpressurecurveswereobtainedfortheparticlelocated 10mawayfromtheseismicsourcetoinvestigatetheinfluencesofthemediaintheoilwellontheenergytransferofthedynamitesource. Effectsofthechargediametersonthedeformationoftheoil wellpipewereanalyzed.Andsomediscussionwasmadeontheeffectsofthechargelengthontheenergytransferofthedynamitesourceandthedeformationoftheoilwellpipe. Thecorrespondingexperimentwasimplementedtocomparewiththenumericalresults. Thenumericalresultsareconsistentwiththeexperimentalobservations. Theresearchcanprovidehelpfortheengineeringapplication oftheRVSPprospecting.
2010, 30(5): 479-486.
doi: 10.11883/1001-1455(2010)05-0479-08
Abstract:
Thedouble-sidedstructureofaverylargecrudecarrier(VLCC)cargoholdwaschosenas theresearchobject.Thenonlinearfiniteelementcode,MSC.Dytranwasappliedtoinvestigatenumericallythecollisiondamagemechanismandcrashworthinessofthisstructureunderfullloadand ballastconditions.Andthecorrespondingparameters,includingfluid-structureinteractionpressure, collisionforce,deformationandenergyabsorbing,werecomputedandcomparedwiththeresultsunderlightloadconditions. Theresultsshowthattheliquidcargoaffectstoacertainextentthestructuraldamagedeformationandcollisionforceinthelaterstageofcollisi nbutinfluencesweaklythe wholecrashworthinessofthisstructure.Ballastwaterhasremarkableeffectondamagemechanism, crashworthinessperformanceanddeformationpatterns.Thefluid-structureinteractionforcecancause significantchangesindeformationpatterns,remarkableincreaseinimpactforceandenergyabsorption, evidentimproveincrashworthiness.
Thedouble-sidedstructureofaverylargecrudecarrier(VLCC)cargoholdwaschosenas theresearchobject.Thenonlinearfiniteelementcode,MSC.Dytranwasappliedtoinvestigatenumericallythecollisiondamagemechanismandcrashworthinessofthisstructureunderfullloadand ballastconditions.Andthecorrespondingparameters,includingfluid-structureinteractionpressure, collisionforce,deformationandenergyabsorbing,werecomputedandcomparedwiththeresultsunderlightloadconditions. Theresultsshowthattheliquidcargoaffectstoacertainextentthestructuraldamagedeformationandcollisionforceinthelaterstageofcollisi nbutinfluencesweaklythe wholecrashworthinessofthisstructure.Ballastwaterhasremarkableeffectondamagemechanism, crashworthinessperformanceanddeformationpatterns.Thefluid-structureinteractionforcecancause significantchangesindeformationpatterns,remarkableincreaseinimpactforceandenergyabsorption, evidentimproveincrashworthiness.
2010, 30(5): 487-492.
doi: 10.11883/1001-1455(2010)05-0487-06
Abstract:
Anexperimentaldevicewasdesignedtoinvestigatetheprocesscharactersofliquidexplosion dispersion.Theliquiddispersionprocesswasrecordedbyusingahigh-speedcamera.Theseveralcasesweretakenintoaccount, whichincludeddifferentexplosivequantitiesanddifferentviscosityliquids. Itisfoundthatassoonasthecontainerisbroken,theliquiddispersesthroughthesplits.Inthe caseofsmallexplosivequantity,theliquiddispersionpatternlookslikeanintercrosstree,then breaksintosmalldroplets.Inthecaseoflargerexplosivequantity,theliquiddispersionpatternlooks likeanannulus.Theliquidannulusconsistsofsmalldroplets,vaporizedliquid,atomizedliquid,or liquidsheet,ligamentsandbigdroplets,dependingontheviscosityoftheliquid.Thewidthofthe liquidannulusincreasesinthedispersionprocess,andtheliquidsheet,ligamentsandbigdropletscan breakintosmalldroplets.
Anexperimentaldevicewasdesignedtoinvestigatetheprocesscharactersofliquidexplosion dispersion.Theliquiddispersionprocesswasrecordedbyusingahigh-speedcamera.Theseveralcasesweretakenintoaccount, whichincludeddifferentexplosivequantitiesanddifferentviscosityliquids. Itisfoundthatassoonasthecontainerisbroken,theliquiddispersesthroughthesplits.Inthe caseofsmallexplosivequantity,theliquiddispersionpatternlookslikeanintercrosstree,then breaksintosmalldroplets.Inthecaseoflargerexplosivequantity,theliquiddispersionpatternlooks likeanannulus.Theliquidannulusconsistsofsmalldroplets,vaporizedliquid,atomizedliquid,or liquidsheet,ligamentsandbigdroplets,dependingontheviscosityoftheliquid.Thewidthofthe liquidannulusincreasesinthedispersionprocess,andtheliquidsheet,ligamentsandbigdropletscan breakintosmalldroplets.
2010, 30(5): 493-498.
doi: 10.11883/1001-1455(2010)05-0493-06
Abstract:
BychoosingthePb3O4,ZrO2andTiO2powdersastheraw material,singleperovskitePb (Zr0.95Ti0.05)O3(PZT95/5)powdersweresynthesizedwithacylindricalshockwaveloadingadvice. Thephase,elementaryvalencestates,molecularstructureandcompositionofPZT95/5werecharacterizedbyX- raydiffraction (XRD)andX-rayphotoelectronspectroscopy (XPS).TheXPSresults showthattherearethecrystallatticesPb,ZrandOofPZTinthepowdersandceramicspreparedby shockwave,withtheexceptionofadsorbedoxygenonthesamplesurface.Andthechemicalcompositionoftheceramicsamplesisneartheidealstoichiometricratio. Inaddition,thebondlengthsof Zr O , Pb O becomeshortundershockcompression,whichenlargesthebindingenergyof Pb4fandZr3dintheshock-synthesizedpowders.TheZr3dspectraoftheceramicspreparedwithsolid- state-synthesizedpowdershavetwopeaksmorethanthoseoftheceramicspreparedwithshocksynthesizedpowdersdo, whichattributestothelowervalencezirconiumionfromthereducedZrO2.
BychoosingthePb3O4,ZrO2andTiO2powdersastheraw material,singleperovskitePb (Zr0.95Ti0.05)O3(PZT95/5)powdersweresynthesizedwithacylindricalshockwaveloadingadvice. Thephase,elementaryvalencestates,molecularstructureandcompositionofPZT95/5werecharacterizedbyX- raydiffraction (XRD)andX-rayphotoelectronspectroscopy (XPS).TheXPSresults showthattherearethecrystallatticesPb,ZrandOofPZTinthepowdersandceramicspreparedby shockwave,withtheexceptionofadsorbedoxygenonthesamplesurface.Andthechemicalcompositionoftheceramicsamplesisneartheidealstoichiometricratio. Inaddition,thebondlengthsof Zr O , Pb O becomeshortundershockcompression,whichenlargesthebindingenergyof Pb4fandZr3dintheshock-synthesizedpowders.TheZr3dspectraoftheceramicspreparedwithsolid- state-synthesizedpowdershavetwopeaksmorethanthoseoftheceramicspreparedwithshocksynthesizedpowdersdo, whichattributestothelowervalencezirconiumionfromthereducedZrO2.
2010, 30(5): 499-504.
doi: 10.11883/1001-1455(2010)05-0499-06
Abstract:
AnimprovedLagrangefiniteelementmethodwasproposedforimpactfractureanaylysis,in whichthenodeseparationtechniquewasusedtoachievemeshseparationandthedistortionerosion methodwasappliedtodealwithseriouslydistortedelements.ByapplyingtheLS-dynasolver,a C++programwasdevelopedtoestablishthecomputationalmodelforthenodeseparationandimplementthedistortionerosion. TheC+ + program wascombinedwiththeLS-dynarestartanalysis functiontoachievefractureanalysis.Ahypervelocityimpactproblemwassimulatedbythenode-separationLagrangeFEMandSPH meshfreemethod,respectively.AndthesimulatedresultswerecomparedwiththeexistingexperimentalresultsandtheEulerEFMresults. Comparisonshowsthatthe node-separationLagrangeFEM takestheadvantagesoffastcalculation,goodstability,andclear boundary,anditcanbeusedtoaccuratelyandeffectivelysimulatehypervelocityimpactproblems.
AnimprovedLagrangefiniteelementmethodwasproposedforimpactfractureanaylysis,in whichthenodeseparationtechniquewasusedtoachievemeshseparationandthedistortionerosion methodwasappliedtodealwithseriouslydistortedelements.ByapplyingtheLS-dynasolver,a C++programwasdevelopedtoestablishthecomputationalmodelforthenodeseparationandimplementthedistortionerosion. TheC+ + program wascombinedwiththeLS-dynarestartanalysis functiontoachievefractureanalysis.Ahypervelocityimpactproblemwassimulatedbythenode-separationLagrangeFEMandSPH meshfreemethod,respectively.AndthesimulatedresultswerecomparedwiththeexistingexperimentalresultsandtheEulerEFMresults. Comparisonshowsthatthe node-separationLagrangeFEM takestheadvantagesoffastcalculation,goodstability,andclear boundary,anditcanbeusedtoaccuratelyandeffectivelysimulatehypervelocityimpactproblems.
2010, 30(5): 505-510.
doi: 10.11883/1001-1455(2010)05-0505-06
Abstract:
Abstract:Themovementofafreelyexpandingringwasanalyzedandtheradialvelocity-timecurveof theexpandingOFHCcopperringwasexperimentallyobtainedbythelaserinterferencetechnique. Thedifferentdatawindowswerechosenfromtheobtainedvelocity-timecurveandtheintercepteddata inthedifferentwindowswerefittedbydifferentmethods.Thentheaccelerationswereacquiredfrom thedifferentialequationsofthevelocities.Thestress-straincurvesweregainedbyprocessingthevelocitiesoftheringunderone- dimensionalstressassumption.Resultsshowthatthereasonableselectionofdatawindowsisthecorrectdata- processingfoundationforexpandingringtests.Whilethe ranksoffittingexpressionsarehigherthan2,theobtainedstress-strainrelationwilllapseformally fromphysicsrules.Butafterthedata,whicharesmoothedbyhigher-rankexpressions,areprocessed bythedirectdifferencemethod,theprocesseddatacanreflectbettertherelationshipbetweenthevelocityhistoryoftheexpandingringanditsinstantaneousstresses. Itexplainsthatthelapseoftheabovefittedstress- strainrelationfromphysicsrulesdoesnotresultfromthedataprocessingmethods butfromtheuncertaintyofthevelocitymeasurementatonepoint.
Abstract:Themovementofafreelyexpandingringwasanalyzedandtheradialvelocity-timecurveof theexpandingOFHCcopperringwasexperimentallyobtainedbythelaserinterferencetechnique. Thedifferentdatawindowswerechosenfromtheobtainedvelocity-timecurveandtheintercepteddata inthedifferentwindowswerefittedbydifferentmethods.Thentheaccelerationswereacquiredfrom thedifferentialequationsofthevelocities.Thestress-straincurvesweregainedbyprocessingthevelocitiesoftheringunderone- dimensionalstressassumption.Resultsshowthatthereasonableselectionofdatawindowsisthecorrectdata- processingfoundationforexpandingringtests.Whilethe ranksoffittingexpressionsarehigherthan2,theobtainedstress-strainrelationwilllapseformally fromphysicsrules.Butafterthedata,whicharesmoothedbyhigher-rankexpressions,areprocessed bythedirectdifferencemethod,theprocesseddatacanreflectbettertherelationshipbetweenthevelocityhistoryoftheexpandingringanditsinstantaneousstresses. Itexplainsthatthelapseoftheabovefittedstress- strainrelationfromphysicsrulesdoesnotresultfromthedataprocessingmethods butfromtheuncertaintyofthevelocitymeasurementatonepoint.
2010, 30(5): 511-516.
doi: 10.11883/1001-1455(2010)05-0511-06
Abstract:
Byapplyingtheprinciple,threedynamicresponsescalingrequirementswereproposedbetweenmodelsandprototypesforstiffenedplatessubjectedtounderwaterblast. Basedontheabove scalingrequirements,ascalingmethodwasputforwardtopredicatethedynamicresponsesofstiffenedplatessubjectedtounderwaterblast, inwhichtheprototypeswasmadeofshipsteelandthe modelswasmadeofmildsteel.Andthefluid-solidcouplingeffectandthestrain-rateeffectwereconsideredinthescalingmethod. Twosampleswerecalculatedtovalidatethescalingmethod.Thescalingmethodcanbeusedtoguidethedynamicresponsepredictionofrealshipstructuressubjectedto underwaterblastbyexperimentalmodelsmadeofmildsteel
Byapplyingtheprinciple,threedynamicresponsescalingrequirementswereproposedbetweenmodelsandprototypesforstiffenedplatessubjectedtounderwaterblast. Basedontheabove scalingrequirements,ascalingmethodwasputforwardtopredicatethedynamicresponsesofstiffenedplatessubjectedtounderwaterblast, inwhichtheprototypeswasmadeofshipsteelandthe modelswasmadeofmildsteel.Andthefluid-solidcouplingeffectandthestrain-rateeffectwereconsideredinthescalingmethod. Twosampleswerecalculatedtovalidatethescalingmethod.Thescalingmethodcanbeusedtoguidethedynamicresponsepredictionofrealshipstructuressubjectedto underwaterblastbyexperimentalmodelsmadeofmildsteel
2010, 30(5): 517-522.
doi: 10.11883/1001-1455(2010)05-0517-06
Abstract:
Basedonbriefanalysisofstatusquoandremovalmechanismofmachiningtechnologiesfor engineeringceramic,amachiningsystemofelectrodearcstrikingmicro-detonation(MDEAS)wasdesignedanddevelopedindependentlybyreferringtothebasictheoryofelectrodedischargeandthe technologyofhigh-efficiencyripplecontrol.Aspecialpulsepowersupply,whichwasthekeypartof thissystem,wasintroducedfromitsstructureandfunctionindetail.AndagreatmanymachiningexperimentsonSi3N4ceramicmaterialwereconductedbytheMDEAStechnologytodeterminetheappliedrangesofthemainm chiningparametersandthemachiningperformancesofthissystem were analyzed.ThentheMDEAStechnologywasbrieflycomparedwithothermachiningtechnologiessuch aslaser,electricaldischarge,plasmaarcandtraditionalgrinding.ResultsdisplaythattheMDEAS technologyisabrand-newandlow-costmachiningtechnology,andithaswideappliedfields.
Basedonbriefanalysisofstatusquoandremovalmechanismofmachiningtechnologiesfor engineeringceramic,amachiningsystemofelectrodearcstrikingmicro-detonation(MDEAS)wasdesignedanddevelopedindependentlybyreferringtothebasictheoryofelectrodedischargeandthe technologyofhigh-efficiencyripplecontrol.Aspecialpulsepowersupply,whichwasthekeypartof thissystem,wasintroducedfromitsstructureandfunctionindetail.AndagreatmanymachiningexperimentsonSi3N4ceramicmaterialwereconductedbytheMDEAStechnologytodeterminetheappliedrangesofthemainm chiningparametersandthemachiningperformancesofthissystem were analyzed.ThentheMDEAStechnologywasbrieflycomparedwithothermachiningtechnologiessuch aslaser,electricaldischarge,plasmaarcandtraditionalgrinding.ResultsdisplaythattheMDEAS technologyisabrand-newandlow-costmachiningtechnology,andithaswideappliedfields.
2010, 30(5): 523-528.
doi: 10.11883/1001-1455(2010)05-0523-06
Abstract:
A modifiedHartmanntubewasusedastheprincipalpartoftheexperimentalsetuptotest theflammablelimitsandcombustionpressureofnaturalgascontainingcarbondioxideatroomtemperatureandatmosphericpressure. Thetriangularflammabilitydiagramandthecombustionpressure distributionwereexperimentallyobtainedfornaturalgascontainingcarbondioxide.Investigatedresultsdisplaythatnaturalgascontainingcarbondioxidehasanarrowerflammabilityregionandlower explosionviolencethanpurenaturalgasdoes.Whenthevolumefractionofcarbondioxideexceeds 13.86%inthemixturegasformedbyleakednaturegasandair,themixturegascanloseflammability. Forthemethane-air-carbondioxidemixturegasintheflammabilityregion,thecombustionpressuredecreaseswiththevolumeratioincreaseofcarbondioxidetomethane.
A modifiedHartmanntubewasusedastheprincipalpartoftheexperimentalsetuptotest theflammablelimitsandcombustionpressureofnaturalgascontainingcarbondioxideatroomtemperatureandatmosphericpressure. Thetriangularflammabilitydiagramandthecombustionpressure distributionwereexperimentallyobtainedfornaturalgascontainingcarbondioxide.Investigatedresultsdisplaythatnaturalgascontainingcarbondioxidehasanarrowerflammabilityregionandlower explosionviolencethanpurenaturalgasdoes.Whenthevolumefractionofcarbondioxideexceeds 13.86%inthemixturegasformedbyleakednaturegasandair,themixturegascanloseflammability. Forthemethane-air-carbondioxidemixturegasintheflammabilityregion,thecombustionpressuredecreaseswiththevolumeratioincreaseofcarbondioxidetomethane.
2010, 30(5): 529-534.
doi: 10.11883/1001-1455(2010)05-0529-06
Abstract:
Physicalandmathematicalmodelsweredevelopedtodescribethekicking-upandexplosion processofdepositedcoaldustduetogasexplosion.Basedonthedevelopedmodels,theprocess,in whichthedepositedcoaldustwaskickedupandinvolvedingasexplosion,wasnumericallysimulated byusingthecommercialcomputationalfluiddynamics(CFD)code,FLUENT.Thesimulatedresults werecomparedwiththeexperimentalresults,andthevelocityandtemperaturefieldsintheexplosion processwereanalyzed.Analysesontheexplosionpressure,velocityandtemperaturefieldsdisplay thatthesimulatedresultscanexpresslyexhibitthekicking-upandexplosionprocessofdepositedcoal dust.
Physicalandmathematicalmodelsweredevelopedtodescribethekicking-upandexplosion processofdepositedcoaldustduetogasexplosion.Basedonthedevelopedmodels,theprocess,in whichthedepositedcoaldustwaskickedupandinvolvedingasexplosion,wasnumericallysimulated byusingthecommercialcomputationalfluiddynamics(CFD)code,FLUENT.Thesimulatedresults werecomparedwiththeexperimentalresults,andthevelocityandtemperaturefieldsintheexplosion processwereanalyzed.Analysesontheexplosionpressure,velocityandtemperaturefieldsdisplay thatthesimulatedresultscanexpresslyexhibitthekicking-upandexplosionprocessofdepositedcoal dust.
2010, 30(5): 535-540.
doi: 10.11883/1001-1455(2010)05-0535-06
Abstract:
TwoexplosioneventsrecordedbystationMDJonOctober9,2006andMay25,2009were investigated,respectively.Theenergyratioofthetwoexplosioneventswasestimatedbycomparing themaximumPphaseamplitudesandthepowerspectrumdensities.Relativityofthetwoexplosioneventsintimeandfrequencydomainswasdeterminedbyusingthecrosscorrelationandthecoherence function.Comparisonbetweenthe2009eventandthe2006eventdisplaysthatthemeanratioofthe maximumPphaseamplitudesinthreecomponentsisabout3.97,themeanratioofthepowerspectrumdensitiesisabout4.5. Itindicatesthattheenergyreleasedbythe2009explosioneventis4-5 timesasmuchasthatreleasedbythe2006explosionevent.ThemeancrosscorrelationofthetwoeventsrecordedinthethreecomponentsofMDJwasabout0.88in1- 4Hz,andthecoherencevalues ofthetwoeventsarearound0.8atthesamefrequencyband.
TwoexplosioneventsrecordedbystationMDJonOctober9,2006andMay25,2009were investigated,respectively.Theenergyratioofthetwoexplosioneventswasestimatedbycomparing themaximumPphaseamplitudesandthepowerspectrumdensities.Relativityofthetwoexplosioneventsintimeandfrequencydomainswasdeterminedbyusingthecrosscorrelationandthecoherence function.Comparisonbetweenthe2009eventandthe2006eventdisplaysthatthemeanratioofthe maximumPphaseamplitudesinthreecomponentsisabout3.97,themeanratioofthepowerspectrumdensitiesisabout4.5. Itindicatesthattheenergyreleasedbythe2009explosioneventis4-5 timesasmuchasthatreleasedbythe2006explosionevent.ThemeancrosscorrelationofthetwoeventsrecordedinthethreecomponentsofMDJwasabout0.88in1- 4Hz,andthecoherencevalues ofthetwoeventsarearound0.8atthesamefrequencyband.
2010, 30(5): 541-545.
doi: 10.11883/1001-1455(2010)05-0541-05
Abstract:
Byadoptingthedigitalhigh-speedphotographyanddynamicelectricalmeasurementtechnique, ascale-reducedmodelwasdesignedtoexperimentallyinvestigatethedynamicdamageprocess ofahorseshoe-shapedundergroundprotectivestructureunderimpactloading.Experimentalresults indicatethatthebottomistheweakestpartofthehorseshoe-shapedstructureandneedbeprotected excessively.Theshockresistanceofthiskindofstructurecanbeevidentlyimprovedbyaddingsteel platesorotherhigh-strengthprotectingmaterialsinitsinnerlayer.Thescale-reducedexperimentwas simulatednumericallybyusingtheLS-DYNAfiniteelementsoftware.Thenumericalresultsareinagreementwiththeexperimentalresults. ItdisplaysthattheLS-DYNAfiniteelementsoftwareisfeasibletobeusedtosimulatethedynamicdamageprocessofthescale- reducedmodelforhorseshoeshapedundergroundprotectivestructures.
Byadoptingthedigitalhigh-speedphotographyanddynamicelectricalmeasurementtechnique, ascale-reducedmodelwasdesignedtoexperimentallyinvestigatethedynamicdamageprocess ofahorseshoe-shapedundergroundprotectivestructureunderimpactloading.Experimentalresults indicatethatthebottomistheweakestpartofthehorseshoe-shapedstructureandneedbeprotected excessively.Theshockresistanceofthiskindofstructurecanbeevidentlyimprovedbyaddingsteel platesorotherhigh-strengthprotectingmaterialsinitsinnerlayer.Thescale-reducedexperimentwas simulatednumericallybyusingtheLS-DYNAfiniteelementsoftware.Thenumericalresultsareinagreementwiththeexperimentalresults. ItdisplaysthattheLS-DYNAfiniteelementsoftwareisfeasibletobeusedtosimulatethedynamicdamageprocessofthescale- reducedmodelforhorseshoeshapedundergroundprotectivestructures.
2010, 30(5): 546-550.
doi: 10.11883/1001-1455(2010)05-0546-05
Abstract:
Copperparticleimpactbehaviorsincoldsprayingwerenumericallysimulatedbyusingthe LS-DYNAprogram.Someimportantaspectsonthe3Dmodelingwereexamined.Effectsofthemeshingsizeonparticlecriticalvelocityandparticledeformationwerealsoinvestigated. Theresultsshow thatthecontoursofthedeformedparticleobtainedbythe3Dmodelaremorecomparabletotheexperimentalobservationthantheprevious2Dsimulate results.Thedistortionofthesolidelementatthe contactzoneinthe3Dmodelismuchweakerthanthesurfaceelementusedinthe2D model.Therefore, nosteepincreaseofeffectiveplasticstrainofelementscanbeobservedduringtheimpact process.Furthermore,themeshingsizealsotakesanimportantroleinthe3Dsimulatedresults.The criticalvelocity,flatteningratioandcompressionratioobtainedbyextrapolationmethodsareingood agreementwiththeexperimentalresults.
Copperparticleimpactbehaviorsincoldsprayingwerenumericallysimulatedbyusingthe LS-DYNAprogram.Someimportantaspectsonthe3Dmodelingwereexamined.Effectsofthemeshingsizeonparticlecriticalvelocityandparticledeformationwerealsoinvestigated. Theresultsshow thatthecontoursofthedeformedparticleobtainedbythe3Dmodelaremorecomparabletotheexperimentalobservationthantheprevious2Dsimulate results.Thedistortionofthesolidelementatthe contactzoneinthe3Dmodelismuchweakerthanthesurfaceelementusedinthe2D model.Therefore, nosteepincreaseofeffectiveplasticstrainofelementscanbeobservedduringtheimpact process.Furthermore,themeshingsizealsotakesanimportantroleinthe3Dsimulatedresults.The criticalvelocity,flatteningratioandcompressionratioobtainedbyextrapolationmethodsareingood agreementwiththeexperimentalresults.
2010, 30(5): 551-555.
doi: 10.11883/1001-1455(2010)05-00551-05
Abstract:
Thewaveletpackettransform,inwhichthewaveletDB8waschosenasthebasisfunction, wasappliedtoanalyzethevibrationsignalsofa25-kg-TNT-equivalentexplosionvessel.Andtheprincipleandcharacteristicsofwaveletpacketanalysiswereintroducedandtheexperimentalvibrationaccelerationsignalsoftheexpl sionvesselwerepresented.Thetime-frequencydistributionsoftheexperimentalsignalswerecalculatedbythewaveletpacketmethod. Theresultsshowthattheenergy distributionofvibrationoftheexplosionvesselhasaverywidefrequencyrangeandfluctuatesintensely, andthequakeprooftrenchattenuatesapproximately97% ofthevibrationenergy.
Thewaveletpackettransform,inwhichthewaveletDB8waschosenasthebasisfunction, wasappliedtoanalyzethevibrationsignalsofa25-kg-TNT-equivalentexplosionvessel.Andtheprincipleandcharacteristicsofwaveletpacketanalysiswereintroducedandtheexperimentalvibrationaccelerationsignalsoftheexpl sionvesselwerepresented.Thetime-frequencydistributionsoftheexperimentalsignalswerecalculatedbythewaveletpacketmethod. Theresultsshowthattheenergy distributionofvibrationoftheexplosionvesselhasaverywidefrequencyrangeandfluctuatesintensely, andthequakeprooftrenchattenuatesapproximately97% ofthevibrationenergy.
2010, 30(5): 556-560.
doi: 10.11883/1001-1455(2010)05-0556-05
Abstract:
Byusingthecatastrophetheory,anonlineardynamicmodelwasproposedtodescribethe rectangularrockpillarinstabilityinducedbyvicinalblasting.Andsufficientandnecessaryconditions wereworkedoutforthepillardynamicinstability.Theproposedcatastrophemodelswereusedtoanalyzetheinfluencesoftheverticalpress, theblastingdisturbingstrengthanditsfrequencyontheinstabilitymechanismoftherectangularrockpillars. Resultsshowasfollows.Itisfeasibletoanalyze theinstabilitymechanismoftherectangularrockpillarsinducedbyvicinalblastingbyusingthecatastrophetheory. Thehigherthevicinalblastingdisturbingstrength,themoreeasilytherockpillarinstabilityoccurs. Theblastingdisturbingstrengthrespondingtotheinstabilityconditionsofrockpillarswillbelesswiththeincreasingoftheverticalpress, andtheinstabilityofrockpillarsbecomes morepossible.Ifthedynamicinstabilityofrockpillarshappens,theblastingdisturbingfrequency mustmeetcertainconditions.
Byusingthecatastrophetheory,anonlineardynamicmodelwasproposedtodescribethe rectangularrockpillarinstabilityinducedbyvicinalblasting.Andsufficientandnecessaryconditions wereworkedoutforthepillardynamicinstability.Theproposedcatastrophemodelswereusedtoanalyzetheinfluencesoftheverticalpress, theblastingdisturbingstrengthanditsfrequencyontheinstabilitymechanismoftherectangularrockpillars. Resultsshowasfollows.Itisfeasibletoanalyze theinstabilitymechanismoftherectangularrockpillarsinducedbyvicinalblastingbyusingthecatastrophetheory. Thehigherthevicinalblastingdisturbingstrength,themoreeasilytherockpillarinstabilityoccurs. Theblastingdisturbingstrengthrespondingtotheinstabilityconditionsofrockpillarswillbelesswiththeincreasingoftheverticalpress, andtheinstabilityofrockpillarsbecomes morepossible.Ifthedynamicinstabilityofrockpillarshappens,theblastingdisturbingfrequency mustmeetcertainconditions.
