2012 Vol. 32, No. 2
Display Method:
2012, 32(2): 113-120.
doi: 10.11883/1001-1455(2012)02-0113-08
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Abstract:
ThedetonationcellsizefortheC2H4-O2 mixturewaspredictedbychemicalkineticsand Ngsmodel.AndtogetherwithLeessurfaceenergymodel,thecriticalenergywasestimatedforthe directinitiationofsphericaldetonationintheC2H4-O2 mixtureunderdifferentinitialpressuresandat differentequivalenceratios.Thedirectinitiationwasperformedviaahighvoltagecapacitorsparkdischargeandthecriticalenergywasaccuratelydeterminedfromthecurrent utputanalysis.Goodagreementwasfoundbetweenthetheoreticalpredictionandtheexperimentalmeasurement. Through steadyZNDanalysesbasedonacomprehensivekineticmechanismandbyusingtheimprovedsemiempiricalcorrelationbyNg, thefactorintherelationbetweenthecellsizeanditsZNDinductionzone length,i.e.,non-dimensionalparameterA,wasdeterminedatdifferentinitialpressuresandequivalenceratiosasfollowing: A=43.815(1+p/p0)-0.12371andA=8.531exp(/3.135)+28.644,respectively. Thecellsizecanbecalculatedultimatelyfromthesecorrelations,andtheexperimentally measuredcellsizesagreewellwiththetheoreticalpredictiondata.Thecellsizeisconsideredasaninputintermediatecharacteristicparameterandusedtoestimatethecriticalenergyfordirectinitiation basedonLeessurfaceenergymodel.Thecombinationofchemicalkineticsandtheoreticalmodels mayformaquantitativetheorytopredictthecriticalenergyfordirectinitiation.Thetheoreticalcurve fitoftheparametricrelationshipbetweenthecriticalinitiationenergyandtheinitialpressureaswell astheequivalenceratioisEc=0.332(p/p0)-2.017andEc=exp[3.951(-1.401)2-1.9],respectively.
ThedetonationcellsizefortheC2H4-O2 mixturewaspredictedbychemicalkineticsand Ngsmodel.AndtogetherwithLeessurfaceenergymodel,thecriticalenergywasestimatedforthe directinitiationofsphericaldetonationintheC2H4-O2 mixtureunderdifferentinitialpressuresandat differentequivalenceratios.Thedirectinitiationwasperformedviaahighvoltagecapacitorsparkdischargeandthecriticalenergywasaccuratelydeterminedfromthecurrent utputanalysis.Goodagreementwasfoundbetweenthetheoreticalpredictionandtheexperimentalmeasurement. Through steadyZNDanalysesbasedonacomprehensivekineticmechanismandbyusingtheimprovedsemiempiricalcorrelationbyNg, thefactorintherelationbetweenthecellsizeanditsZNDinductionzone length,i.e.,non-dimensionalparameterA,wasdeterminedatdifferentinitialpressuresandequivalenceratiosasfollowing: A=43.815(1+p/p0)-0.12371andA=8.531exp(/3.135)+28.644,respectively. Thecellsizecanbecalculatedultimatelyfromthesecorrelations,andtheexperimentally measuredcellsizesagreewellwiththetheoreticalpredictiondata.Thecellsizeisconsideredasaninputintermediatecharacteristicparameterandusedtoestimatethecriticalenergyfordirectinitiation basedonLeessurfaceenergymodel.Thecombinationofchemicalkineticsandtheoreticalmodels mayformaquantitativetheorytopredictthecriticalenergyfordirectinitiation.Thetheoreticalcurve fitoftheparametricrelationshipbetweenthecriticalinitiationenergyandtheinitialpressureaswell astheequivalenceratioisEc=0.332(p/p0)-2.017andEc=exp[3.951(-1.401)2-1.9],respectively.
2012, 32(2): 121-128.
doi: 10.11883/1001-1455(2012)02-0121-08
Abstract:
Thisreviewaimsatthemainprogressesofthemodelsdescribingshock-inducedignitionand detonationofsolidheterogeneousexplosivessince1980s.These modelscanbedividedintothree types:empiricalmodels,micromechanicalmodelsandmoleculardynamicsbasedmodels.Thecorrespondingtheoriestothesemodelsareanalyzedaswellastheexistentdifficultiesintheoreticalinvestigationandpracticalapplicat on,andtheapplicationpossibilitiesofthesemodelstocomplexengineeringproblemsareexplored. Investigatedresultsshowthatthemicromechanicalmodelstakeonunambiguousconceptsandcanpredicttheexperimentalresults, andtheyhavegoodapplicationprospectsin engineeringpractice.Atlast,someadvicesaboutthemicromechanicalmodelsaregiven.
Thisreviewaimsatthemainprogressesofthemodelsdescribingshock-inducedignitionand detonationofsolidheterogeneousexplosivessince1980s.These modelscanbedividedintothree types:empiricalmodels,micromechanicalmodelsandmoleculardynamicsbasedmodels.Thecorrespondingtheoriestothesemodelsareanalyzedaswellastheexistentdifficultiesintheoreticalinvestigationandpracticalapplicat on,andtheapplicationpossibilitiesofthesemodelstocomplexengineeringproblemsareexplored. Investigatedresultsshowthatthemicromechanicalmodelstakeonunambiguousconceptsandcanpredicttheexperimentalresults, andtheyhavegoodapplicationprospectsin engineeringpractice.Atlast,someadvicesaboutthemicromechanicalmodelsaregiven.
2012, 32(2): 129-135.
doi: 10.11883/1001-1455(2012)02-0129-07
Abstract:
AthermaltransfermodelforAl2O3ceramicsduringmicro-detonationofstrikingarcmachining( MDSAM)wasestablished.Basedonthefiniteelementtheory,thetemperaturefieldofAl2O3 ceramicsduringMDSAM wassimulatedwiththeaidoftheANSYSsoftware.Combinedwiththematerialproperties, thesimulatedcavitydimensionwascomparedwiththemachiningexperimentalresultandtheeffectsofthemachiningparametersonthetemperaturef eldwereanalyzed.ThesimulatedresultsshowthatthehighesttemperatureofAl2O3ceramicsduringMDSAMcanreach13435℃ withthegivenmachiningparameters.Theheat-affectedzoneisquitesmallandthemachiningtestis consistentwiththesimulatedresults.Withtheincreaseofthepulsewidthandtheworkingcurrent, thetemperatureoftheprocessingregionandtheradiusanddepthofthecavityincrease.Thetemperaturedecreaseswiththeincreaseofthenozzleradius, whereasthediameter-to-depthratioofthecavity increases.Thesimulatedresultscanprovideanimportantreferenceforthepredictionofthesurface topography,thedisclosureofthematerialremovalmechanism,andtheoptimizationofthemachining parametersforAl2O3ceramicsduringMDSAM.
AthermaltransfermodelforAl2O3ceramicsduringmicro-detonationofstrikingarcmachining( MDSAM)wasestablished.Basedonthefiniteelementtheory,thetemperaturefieldofAl2O3 ceramicsduringMDSAM wassimulatedwiththeaidoftheANSYSsoftware.Combinedwiththematerialproperties, thesimulatedcavitydimensionwascomparedwiththemachiningexperimentalresultandtheeffectsofthemachiningparametersonthetemperaturef eldwereanalyzed.ThesimulatedresultsshowthatthehighesttemperatureofAl2O3ceramicsduringMDSAMcanreach13435℃ withthegivenmachiningparameters.Theheat-affectedzoneisquitesmallandthemachiningtestis consistentwiththesimulatedresults.Withtheincreaseofthepulsewidthandtheworkingcurrent, thetemperatureoftheprocessingregionandtheradiusanddepthofthecavityincrease.Thetemperaturedecreaseswiththeincreaseofthenozzleradius, whereasthediameter-to-depthratioofthecavity increases.Thesimulatedresultscanprovideanimportantreferenceforthepredictionofthesurface topography,thedisclosureofthematerialremovalmechanism,andtheoptimizationofthemachining parametersforAl2O3ceramicsduringMDSAM.
2012, 32(2): 136-142.
doi: 10.11883/1001-1455(2012)02-0136-07
Abstract:
Destructiontestswereperformedonacylindricalexplosioncontainmentvessel(ECV)by applyingtheexplosiveloadswiththeincreasingchargemassesofTNT.Anadiabaticshearfailure modeforECVswaspresentedbasedonthefractureandthemicro-opticalobservationofthedestructedvessel. AdamageevolutionmodelforECVssubjectedtoadiabaticshearwasconstructed,where themechanicalconditionsincludingstrainrateandstrain werelinked withthedifferentevolution statesoftheadiabaticshearbands(ASBs).AndthesemechanicalconditionswereemployedinthenumericalcodeasthefailurecriteriatosimulatethetransientprocessoftheASBevolution. Thesimulatedfractureprofileshowsagoodagreementwiththeexperimentalresult. Thesimulatedresultindicatesthattherate- dependentcriticalstrain,aswellasexplosiveload,governstheadiabaticshearfailuremode. ThoughtheinitialmaterialimperfectionignitestheASBs,ithasaminorinfluenceonthe finalfractureprofile.FortheECVswiththeadiabaticshearfailuremode,thecrack (orASB)expandsfasterthanforthosewiththeplasticinstabilityfailuremode.
Destructiontestswereperformedonacylindricalexplosioncontainmentvessel(ECV)by applyingtheexplosiveloadswiththeincreasingchargemassesofTNT.Anadiabaticshearfailure modeforECVswaspresentedbasedonthefractureandthemicro-opticalobservationofthedestructedvessel. AdamageevolutionmodelforECVssubjectedtoadiabaticshearwasconstructed,where themechanicalconditionsincludingstrainrateandstrain werelinked withthedifferentevolution statesoftheadiabaticshearbands(ASBs).AndthesemechanicalconditionswereemployedinthenumericalcodeasthefailurecriteriatosimulatethetransientprocessoftheASBevolution. Thesimulatedfractureprofileshowsagoodagreementwiththeexperimentalresult. Thesimulatedresultindicatesthattherate- dependentcriticalstrain,aswellasexplosiveload,governstheadiabaticshearfailuremode. ThoughtheinitialmaterialimperfectionignitestheASBs,ithasaminorinfluenceonthe finalfractureprofile.FortheECVswiththeadiabaticshearfailuremode,thecrack (orASB)expandsfasterthanforthosewiththeplasticinstabilityfailuremode.
2012, 32(2): 143-149.
doi: 10.11883/1001-1455(2012)02-0143-07
Abstract:
Basedonthethermodynamicsandthethree-termequationofstate,theshocktemperature ofporousmetalwastheoreticallyanalyzedfortheHugoniotadiabat,stateparametersandisovolumic extrapolationofsolidmaterials.Bycombiningthecalculatedcoldenergy,thecalculatedcoldpressure andtheHugoniotequationsofsolidmetalandporousmetal,anewmethodwaspresentedtocalculate theshocktemperatureofporousmetal.Theporousironwaschosenasanexampletodiscusstheinfluencesoftheseveralphysicalparametersonthecalculatedresultbythepresentedmethod Thecalculationexampleshowsthatthecalculatedshocktemperaturefortheporousironisingoodagreement withtheexistentexperimentaldataandthecorrespondingerrorsarelessthan5percent.Andthe shocktemperatureofporousmetalcanbelittleinfluencedbytheGrneisenparameterandtheelectronicGrneisenparameter, butitcanbeinfluencedevidentlybymaterialcompactness,shockpressureandelectronicspecificheatcoefficient.
Basedonthethermodynamicsandthethree-termequationofstate,theshocktemperature ofporousmetalwastheoreticallyanalyzedfortheHugoniotadiabat,stateparametersandisovolumic extrapolationofsolidmaterials.Bycombiningthecalculatedcoldenergy,thecalculatedcoldpressure andtheHugoniotequationsofsolidmetalandporousmetal,anewmethodwaspresentedtocalculate theshocktemperatureofporousmetal.Theporousironwaschosenasanexampletodiscusstheinfluencesoftheseveralphysicalparametersonthecalculatedresultbythepresentedmethod Thecalculationexampleshowsthatthecalculatedshocktemperaturefortheporousironisingoodagreement withtheexistentexperimentaldataandthecorrespondingerrorsarelessthan5percent.Andthe shocktemperatureofporousmetalcanbelittleinfluencedbytheGrneisenparameterandtheelectronicGrneisenparameter, butitcanbeinfluencedevidentlybymaterialcompactness,shockpressureandelectronicspecificheatcoefficient.
2012, 32(2): 150-156.
doi: 10.11883/1001-1455(2012)02-0150-07
Abstract:
Tosimulatethemovingofaxisymmetricdetonationfrontontrianglesandquadrilateralsusingthelevelsetmethod, assumingthatthedetonationnormalvelocityisthelinearfunctionofcurvature, anaxisymmtriclevelsetequationisgainedbytheuseofcoordinatetransformation.Theconvectiontermofthelevelsetequationissolvedbythepositivescheme, andthecurvaturetermissolved bytheGalerkinisoparametricfiniteelementmethodandthesemi-implicittimesteppingtechnique. Ontrianglesandquadrilaterals,theschemeofthelevelsetequationscontainingcurvatureishigher thanfirstorderaccuracyinL2andL norms.Thecomputationalexampleisgivenofnonsmoothlevel setsshorteningstablybythelocalcurvatureontheunstructuredmixedmeshes.Theexampleofmultipledetonationfrontscollidingshowsthattheschemeofthispapercanbeusedtosimulatethepropagationofdetonationfronto curvature.
Tosimulatethemovingofaxisymmetricdetonationfrontontrianglesandquadrilateralsusingthelevelsetmethod, assumingthatthedetonationnormalvelocityisthelinearfunctionofcurvature, anaxisymmtriclevelsetequationisgainedbytheuseofcoordinatetransformation.Theconvectiontermofthelevelsetequationissolvedbythepositivescheme, andthecurvaturetermissolved bytheGalerkinisoparametricfiniteelementmethodandthesemi-implicittimesteppingtechnique. Ontrianglesandquadrilaterals,theschemeofthelevelsetequationscontainingcurvatureishigher thanfirstorderaccuracyinL2andL norms.Thecomputationalexampleisgivenofnonsmoothlevel setsshorteningstablybythelocalcurvatureontheunstructuredmixedmeshes.Theexampleofmultipledetonationfrontscollidingshowsthattheschemeofthispapercanbeusedtosimulatethepropagationofdetonationfronto curvature.
2012, 32(2): 157-163.
doi: 10.11883/1001-1455(2012)02-0157-07
Abstract:
Toovercomethedifficultiesinsimulatingaccuratelytheblastingvibrationofsurrounding rock,anequivalentsimulationmethodwaspresented.Theequivalentelasticboundarysubjectedto theblastingloadwasdevelopedformultipleboreholesaccordingtothespatialcharacterofrockdamagearoundboreholes. Blastingloadsontheequivalentboundaryvaryingalongtheboreholeaxiswas calculatedtheoreticallythroughanalyzingtheexpansionofboreholevolume,thedevelopmentof cracks,themovementofstemmingandtheoutburstofdetonationgases.Combinedwiththeblasting excavationoftheNo.1tailracetunnelinPubugouHydropowerStation,particlevibrationvelocitiesin thesurroundingrockweresimulatedbyemployingthisequivalentmethodbasedonthedynamicfinite elementmethod.Thecomparisonbetweenthesimulationresultsandthemonitoringdataindicates thatthisequivalentsimulationmethodisapplicabletocalculatingtheresponseofsurroundingrock duringblastingexcavation;andthattheselectionofmechanicalparametersoftherockneartheequivalentelasticboundaryhasasignificantimpactoncalculationresults.
Toovercomethedifficultiesinsimulatingaccuratelytheblastingvibrationofsurrounding rock,anequivalentsimulationmethodwaspresented.Theequivalentelasticboundarysubjectedto theblastingloadwasdevelopedformultipleboreholesaccordingtothespatialcharacterofrockdamagearoundboreholes. Blastingloadsontheequivalentboundaryvaryingalongtheboreholeaxiswas calculatedtheoreticallythroughanalyzingtheexpansionofboreholevolume,thedevelopmentof cracks,themovementofstemmingandtheoutburstofdetonationgases.Combinedwiththeblasting excavationoftheNo.1tailracetunnelinPubugouHydropowerStation,particlevibrationvelocitiesin thesurroundingrockweresimulatedbyemployingthisequivalentmethodbasedonthedynamicfinite elementmethod.Thecomparisonbetweenthesimulationresultsandthemonitoringdataindicates thatthisequivalentsimulationmethodisapplicabletocalculatingtheresponseofsurroundingrock duringblastingexcavation;andthattheselectionofmechanicalparametersoftherockneartheequivalentelasticboundaryhasasignificantimpactoncalculationresults.
2012, 32(2): 164-168.
doi: 10.11883/1001-1455(2012)02-0164-05
Abstract:
Toexploretheinfluenceoftheafter-burningonthestrengthoftheshockwavesproducedby thethermobaricexplosiveexplosioninair,experimentsandnumericalsimulationswereperformedto investigatetheenergyoutputstructure.Theresultsshowthattherelietwopeaksonthepressuretimecurvesinthenearfieldandalongpositivepressureperiodinthefarfield. Theimpulseofthe thermobaricexplosiveinthepositivepressureperiodis1.6~1.8timesasmuchasthatoftheTNT explosivewiththesamemass.TheanalysisoftheJWL-Millermodelparametersrevealsthattheenergyreleasedbytheafter- burningreactionoccupiesaboutone-thirdsofthetotalenergy.Furthermore, thereactiondegreeevolutioncurvewasobtainedforthenonidealcomponent.Inthecaseof completeburning,theafter-burningreactioncanlast400ms.Itindicatesthattheafter-burningof highenergyadditivescanevidentlyenhancethepowerofthermobaricexplosive.
Toexploretheinfluenceoftheafter-burningonthestrengthoftheshockwavesproducedby thethermobaricexplosiveexplosioninair,experimentsandnumericalsimulationswereperformedto investigatetheenergyoutputstructure.Theresultsshowthattherelietwopeaksonthepressuretimecurvesinthenearfieldandalongpositivepressureperiodinthefarfield. Theimpulseofthe thermobaricexplosiveinthepositivepressureperiodis1.6~1.8timesasmuchasthatoftheTNT explosivewiththesamemass.TheanalysisoftheJWL-Millermodelparametersrevealsthattheenergyreleasedbytheafter- burningreactionoccupiesaboutone-thirdsofthetotalenergy.Furthermore, thereactiondegreeevolutioncurvewasobtainedforthenonidealcomponent.Inthecaseof completeburning,theafter-burningreactioncanlast400ms.Itindicatesthattheafter-burningof highenergyadditivescanevidentlyenhancethepowerofthermobaricexplosive.
2012, 32(2): 169-173.
doi: 10.11883/1001-1455(2012)02-0169-05
Abstract:
Three-pointdynamicbendingtestsandquasi-statictestswerecarriedout,respectively.And theexperimentalmethodsandthecorrespondingexperimentalprinciplewereintroducedindetails.In theexperiments,aluminumalloy6063T6waschosenasthethin-walledtubematerial,thetubeswith threedifferentthicknessesof1.0,1.5and1.8mmhadanidenticaloutsidediameterof38mm,and thealuminum-alloyfoam withtwodifferentdensitieswasusedasfillingcores.Theexperimentalresultsdisplaythatunderlow- velocityimpact,thethinner-walledtubesarepronetotensiledamageat theloweredgesofthemiddlesections;thatduetotheinertiaeffect,thepunchforcesunderlow-velocityimpactarehigherthanthoseunderquasi- staticload.Inaddition,thelocalindentationbylowvelocityimpactislargerthanthatbyquasi- staticload,whichmakesthetensilefailureofthelower edgeofthestructuredelay.Hence,thebendingstiffnessofthemiddlesectionsunderlow-velocityimpactsignificantlydecreasesandtheultimatedisplacementwhenthestructuresfractureincreases.
Three-pointdynamicbendingtestsandquasi-statictestswerecarriedout,respectively.And theexperimentalmethodsandthecorrespondingexperimentalprinciplewereintroducedindetails.In theexperiments,aluminumalloy6063T6waschosenasthethin-walledtubematerial,thetubeswith threedifferentthicknessesof1.0,1.5and1.8mmhadanidenticaloutsidediameterof38mm,and thealuminum-alloyfoam withtwodifferentdensitieswasusedasfillingcores.Theexperimentalresultsdisplaythatunderlow- velocityimpact,thethinner-walledtubesarepronetotensiledamageat theloweredgesofthemiddlesections;thatduetotheinertiaeffect,thepunchforcesunderlow-velocityimpactarehigherthanthoseunderquasi- staticload.Inaddition,thelocalindentationbylowvelocityimpactislargerthanthatbyquasi- staticload,whichmakesthetensilefailureofthelower edgeofthestructuredelay.Hence,thebendingstiffnessofthemiddlesectionsunderlow-velocityimpactsignificantlydecreasesandtheultimatedisplacementwhenthestructuresfractureincreases.
2012, 32(2): 174-178.
doi: 10.11883/1001-1455(2012)02-0174-05
Abstract:
Cu3(C6H5O3)2 wasmixedwitholeicacidandRDXaccordingtoacertainproportiontopreparethereactant. Theobtainedmixedexplosiveswereignitedbythedetonatorsundernitrogenprotectioninanexplosionvesseltosynthesizecarbon- encapsulatedcoppernanoparticles.Thedetonation productswereblackpowders.Theshape,compositionandstructureofthedetonationproductswere characterizedbyusingatransmissionelectronmicroscope(TEM)andX-raydiffraction(XRD)analysis. TheXRDpatternsshowthatthecarbon-encapsulatedcoppernanoparticlesareofcubiccrystal structureandtheaverageparticlesizeis20.2nmindiameter.TheTEMphotographsdisplaythatthe carbon-encapsulatedcoppernanoparticlesareofsphericalshapeabout10~40nmindiameterwith3~ 5nmthickgraphiticcarbonoramorphouscarbonshells.Theresultsindicatethatthedetonationsoot consistsofcopperascores,andgraphiteandamorphouscarbonascarbon-coatinglayers.Meanwhile, theformationmechanismofthecarbon-encapsulatedcopperwastentativelydiscussed.
Cu3(C6H5O3)2 wasmixedwitholeicacidandRDXaccordingtoacertainproportiontopreparethereactant. Theobtainedmixedexplosiveswereignitedbythedetonatorsundernitrogenprotectioninanexplosionvesseltosynthesizecarbon- encapsulatedcoppernanoparticles.Thedetonation productswereblackpowders.Theshape,compositionandstructureofthedetonationproductswere characterizedbyusingatransmissionelectronmicroscope(TEM)andX-raydiffraction(XRD)analysis. TheXRDpatternsshowthatthecarbon-encapsulatedcoppernanoparticlesareofcubiccrystal structureandtheaverageparticlesizeis20.2nmindiameter.TheTEMphotographsdisplaythatthe carbon-encapsulatedcoppernanoparticlesareofsphericalshapeabout10~40nmindiameterwith3~ 5nmthickgraphiticcarbonoramorphouscarbonshells.Theresultsindicatethatthedetonationsoot consistsofcopperascores,andgraphiteandamorphouscarbonascarbon-coatinglayers.Meanwhile, theformationmechanismofthecarbon-encapsulatedcopperwastentativelydiscussed.
2012, 32(2): 179-184.
doi: 10.11883/1001-1455(2012)02-0179-06
Abstract:
TomeasurethedispersionofthesignalopticalfibersinVISAR,asetupwasbuiltbasedon thetimedomainmethod.Thesetupismadeupofapicosecondlaser,afast-responsephotodetector andabroadbanddigitaloscilloscope,whichcanaffordthe3dBdurationoftheimpulseresponsefunctionbymeasuringtheopticalpulsedurationsinandoutthemeasuredfiber. Thissetupwasusedto characterizethedispersionpropertiesofa123-m-lengthgradientindexfiberanda10-m-lengthstepindexfiberatabout532nm, respectively.Theobtaineddispersiontimeofthegradientindexfiberis (68316)psandthecorrespondingfrequencyresponse3dBbandwidthisabout646MHz.Theseof thestepindexfiberare(163114)psand271MHz,respectively.Uncertaintyanalysisofthemeasuredresultswasperformed, andthemeasuredresultswerecomparedwiththetheoreticalcalculations. Itdisplaysthatthemeasuredresultsareconsistentwiththetheoreticalcalculations.Thebuilt setupcanaffordasimpleanddependabledispersiontimemeasurementforthesignalopticalfibersin VISARapplications,therebyitcanprovidereferenceforreasonablychoosingthetypeandlengthof thesignalopticalfibersinexperiments.
TomeasurethedispersionofthesignalopticalfibersinVISAR,asetupwasbuiltbasedon thetimedomainmethod.Thesetupismadeupofapicosecondlaser,afast-responsephotodetector andabroadbanddigitaloscilloscope,whichcanaffordthe3dBdurationoftheimpulseresponsefunctionbymeasuringtheopticalpulsedurationsinandoutthemeasuredfiber. Thissetupwasusedto characterizethedispersionpropertiesofa123-m-lengthgradientindexfiberanda10-m-lengthstepindexfiberatabout532nm, respectively.Theobtaineddispersiontimeofthegradientindexfiberis (68316)psandthecorrespondingfrequencyresponse3dBbandwidthisabout646MHz.Theseof thestepindexfiberare(163114)psand271MHz,respectively.Uncertaintyanalysisofthemeasuredresultswasperformed, andthemeasuredresultswerecomparedwiththetheoreticalcalculations. Itdisplaysthatthemeasuredresultsareconsistentwiththetheoreticalcalculations.Thebuilt setupcanaffordasimpleanddependabledispersiontimemeasurementforthesignalopticalfibersin VISARapplications,therebyitcanprovidereferenceforreasonablychoosingthetypeandlengthof thesignalopticalfibersinexperiments.
2012, 32(2): 185-189.
doi: 10.11883/1001-1455(2012)02-0185-05
Abstract:
Basedonthetheoryofrockblasting,theactionmechanismofexplosionstresswaveincoal wasanalyzed.Thedamagefracturecriteriaforcoalsubjectedtoexplosionstresswavewasexplored accordingtothedamagemechanicstheory.And,simulationexperimentswereconductedtoobtainthe attenuationlawofexplosionstresswavepropagationincoal.Theexperimentalresultsshowthatthe stresswaveateachmeasuredpointcontainstwoormorewaveforms,therearecompressionphaseand tensilephaseinthefirstwave,thewaveformofwhichissimpleandsmooth,andthesecondwaveis theresultofavarietyofaction,thewaveformofwhichiscomplex;thatthecoalmediaisfirstunder compressivestressandthenundertensilestress,theactiontimeofthecompressivestresswasshorter thanthatofthetensilestress;andthatthedecayrateofexplosionstresswaveincoalisfasterthanin generalrock.Themaineffectsofexplosionstresswaveincoalconsistofformingasmallnumberof newcrannies,activatingthenativecranny,andbreakingthebalanceofcoalgas.
Basedonthetheoryofrockblasting,theactionmechanismofexplosionstresswaveincoal wasanalyzed.Thedamagefracturecriteriaforcoalsubjectedtoexplosionstresswavewasexplored accordingtothedamagemechanicstheory.And,simulationexperimentswereconductedtoobtainthe attenuationlawofexplosionstresswavepropagationincoal.Theexperimentalresultsshowthatthe stresswaveateachmeasuredpointcontainstwoormorewaveforms,therearecompressionphaseand tensilephaseinthefirstwave,thewaveformofwhichissimpleandsmooth,andthesecondwaveis theresultofavarietyofaction,thewaveformofwhichiscomplex;thatthecoalmediaisfirstunder compressivestressandthenundertensilestress,theactiontimeofthecompressivestresswasshorter thanthatofthetensilestress;andthatthedecayrateofexplosionstresswaveincoalisfasterthanin generalrock.Themaineffectsofexplosionstresswaveincoalconsistofformingasmallnumberof newcrannies,activatingthenativecranny,andbreakingthebalanceofcoalgas.
2012, 32(2): 190-195.
doi: 10.11883/1001-1455(2012)02-0190-06
Abstract:
Aseriesofcylindertestswerecarriedouttodeterminethedynamicpropertiesof7A55aluminumalloysubjectedtointernalexplosiveloading. Thefracturemorphologyandmicrostructureof thedisruptivespecimenwereanalyzedusingthescanningelectronmicroscopyandtheopticalmicroscope. Theresultsshowthattheinternalexplosiveloading,which7A55aluminumalloycanbear,is 360MPaontheexperimentalconditions.The7A55aluminumalloycylinderunderexplosiveloading mayundergoshearfracture,andthecrackinthecylinderspecimenandtheradialdirectionofthecylinderwalllieatanangleofabout45degrees. Thedeformationband,adiabaticshearbandsandcracks canbefoundinthemicrostructureoftheinnerwall,whichspreadalongthemaximumshearstress plane.
Aseriesofcylindertestswerecarriedouttodeterminethedynamicpropertiesof7A55aluminumalloysubjectedtointernalexplosiveloading. Thefracturemorphologyandmicrostructureof thedisruptivespecimenwereanalyzedusingthescanningelectronmicroscopyandtheopticalmicroscope. Theresultsshowthattheinternalexplosiveloading,which7A55aluminumalloycanbear,is 360MPaontheexperimentalconditions.The7A55aluminumalloycylinderunderexplosiveloading mayundergoshearfracture,andthecrackinthecylinderspecimenandtheradialdirectionofthecylinderwalllieatanangleofabout45degrees. Thedeformationband,adiabaticshearbandsandcracks canbefoundinthemicrostructureoftheinnerwall,whichspreadalongthemaximumshearstress plane.
2012, 32(2): 196-202.
doi: 10.11883/1001-1455(2012)02-0196-07
Abstract:
Toovercomethedifficultyinusingthedeep-holepre-splittingblastingtechnologyinthesoft coalseamspronetoresultingintheboreholecollapse,anewmethodwasappliedtoincreasingthegas drainagerate,inwhichtherocknearbythecoalseamwasexplodedatthebottomofthelaneway.The theoriesforthetechniquewereexploredbynumericalsimulation.Layoutsofblastholesanddrain holeswerecomparedthesinglecoalseam andthecoal-rock media.Fivenumericalcomputational modelswereconstructedbyDYNA3D,includingasinglecoalmodelandfourcoal-rockmodelswith thedifferentdistancebetweentheblastholeandthedrainhole.Thecorrespondingeffectivestress wascomputedalongthelinkinglineoftheblastholeandthedrainhole.Thecomputationalresults showthattheattenuationoftheeffectivestressfromtheblastholetothedrainholeismoreinthe coal-rockmediathaninthesinglecoal,whereastheeffectivestressdifferencebetweenthetwomedia decreasesinthecoalseamsadjacenttothedrainholes.Thedistributionoftheeffectivestressalong theaxisofthedrainholeissignificanttothedraineffect.Themeaneffectivestressalongtheaxisof thedrainholeincoal-rock media,whenthedistancebetweentheblastholeandthedrainholeis 2.0m,isappropriatelythesameasthatinthesinglecoalseam,whenthedistancebetweentheblast holeandthedrainholeis3.0m.Anditcanbeusedasthelayoutparametertokeepthesameblast effectinthecoal-rockmediaasinthesinglecoalseam.
Toovercomethedifficultyinusingthedeep-holepre-splittingblastingtechnologyinthesoft coalseamspronetoresultingintheboreholecollapse,anewmethodwasappliedtoincreasingthegas drainagerate,inwhichtherocknearbythecoalseamwasexplodedatthebottomofthelaneway.The theoriesforthetechniquewereexploredbynumericalsimulation.Layoutsofblastholesanddrain holeswerecomparedthesinglecoalseam andthecoal-rock media.Fivenumericalcomputational modelswereconstructedbyDYNA3D,includingasinglecoalmodelandfourcoal-rockmodelswith thedifferentdistancebetweentheblastholeandthedrainhole.Thecorrespondingeffectivestress wascomputedalongthelinkinglineoftheblastholeandthedrainhole.Thecomputationalresults showthattheattenuationoftheeffectivestressfromtheblastholetothedrainholeismoreinthe coal-rockmediathaninthesinglecoal,whereastheeffectivestressdifferencebetweenthetwomedia decreasesinthecoalseamsadjacenttothedrainholes.Thedistributionoftheeffectivestressalong theaxisofthedrainholeissignificanttothedraineffect.Themeaneffectivestressalongtheaxisof thedrainholeincoal-rock media,whenthedistancebetweentheblastholeandthedrainholeis 2.0m,isappropriatelythesameasthatinthesinglecoalseam,whenthedistancebetweentheblast holeandthedrainholeis3.0m.Anditcanbeusedasthelayoutparametertokeepthesameblast effectinthecoal-rockmediaasinthesinglecoalseam.
2012, 32(2): 203-210.
doi: 10.11883/1001-1455(2012)02-0203-08
Abstract:
Itisasafetyguaranteeforexploration,developmentandutilizationofnaturalgascontaining highcarbondioxidecomponenttograsptheexplosioncharacteristicsofmethaneandcarbondioxide gasmixtures.Meanwhile,itisvaluableguidancefortheindustrialprocessesinvolvingmethaneand carbondioxidesuchascoalgasification,inertization,explosionsuppressionandexplosionventing,to masterrelatedexplosioncharacteristics.Inordertopromoteprogressofrelevantsubject,experimentalandtheoreticalinvestigationonexplosioncharacteristicsofmethaneandcarbondioxidegasmixtureisreviewedsystematicallyi thispaper,includingtheexperimentsrelatedtoflammabilityregion, explosionpressureandinertizationandtheoreticalpredictionofflammabilitylimits.Progress andproblemsthatneedtobesolvedineveryfieldareanalyzed.Finally,thefuturehighlightsinthe followingthreeaspectsareexpected:firstly,howtoimprovetheintegrality,comparabilityandapplicabilityofexperimentaldata; secondly,themethodsandindexesofreliabilityassessmentfortheoreticalprediction; furthermore,howtoextendapplicabilityoftheoreticalpredictionfromatnormaltemperatureandpressureconditionstomorecomplexsituations.
Itisasafetyguaranteeforexploration,developmentandutilizationofnaturalgascontaining highcarbondioxidecomponenttograsptheexplosioncharacteristicsofmethaneandcarbondioxide gasmixtures.Meanwhile,itisvaluableguidancefortheindustrialprocessesinvolvingmethaneand carbondioxidesuchascoalgasification,inertization,explosionsuppressionandexplosionventing,to masterrelatedexplosioncharacteristics.Inordertopromoteprogressofrelevantsubject,experimentalandtheoreticalinvestigationonexplosioncharacteristicsofmethaneandcarbondioxidegasmixtureisreviewedsystematicallyi thispaper,includingtheexperimentsrelatedtoflammabilityregion, explosionpressureandinertizationandtheoreticalpredictionofflammabilitylimits.Progress andproblemsthatneedtobesolvedineveryfieldareanalyzed.Finally,thefuturehighlightsinthe followingthreeaspectsareexpected:firstly,howtoimprovetheintegrality,comparabilityandapplicabilityofexperimentaldata; secondly,themethodsandindexesofreliabilityassessmentfortheoreticalprediction; furthermore,howtoextendapplicabilityoftheoreticalpredictionfromatnormaltemperatureandpressureconditionstomorecomplexsituations.
2012, 32(2): 211-215.
doi: 10.11883/1001-1455(2012)02-0211-05
Abstract:
Abstract:Heidaigouopen-pitcoalminewaschosenasanexampletoexploretheinfluencesofbench heightoncastblastinginopen-pitcoalmines.Theoreticalanalysesandsitetestswerecarriedout,respectively. Investigatedresultsdisplaythatwiththeincreaseofthebenchheight,themaximumcast distanceoftheblastmuckpileaswellasthecastpercentageincreases,andtheshapeoftheblast muckpilebecomessmoother,ontheotherhand,thehigherthebench,themoreslowlythecastpercentageincreases. Whentheunitexplosiveconsumptionisequalto0.70kg/m3andthebenchishigherthan37m, withtheincreaseofthebenchheight,thecastpercentageincreasesslowly,evenstays at47percent.Here,itissubjecttomineconditionsandminingequipments,whichsimplyraisesthe benchheighttoobtainahighercastpercentage.
Abstract:Heidaigouopen-pitcoalminewaschosenasanexampletoexploretheinfluencesofbench heightoncastblastinginopen-pitcoalmines.Theoreticalanalysesandsitetestswerecarriedout,respectively. Investigatedresultsdisplaythatwiththeincreaseofthebenchheight,themaximumcast distanceoftheblastmuckpileaswellasthecastpercentageincreases,andtheshapeoftheblast muckpilebecomessmoother,ontheotherhand,thehigherthebench,themoreslowlythecastpercentageincreases. Whentheunitexplosiveconsumptionisequalto0.70kg/m3andthebenchishigherthan37m, withtheincreaseofthebenchheight,thecastpercentageincreasesslowly,evenstays at47percent.Here,itissubjecttomineconditionsandminingequipments,whichsimplyraisesthe benchheighttoobtainahighercastpercentage.
2012, 32(2): 216-220.
doi: 10.11883/1001-1455(2012)02-0216-05
Abstract:
Theemulsionexplosiveswerechargedintothecurvedgroovemachinedonanironplate. Thedetonationvelocitiesoftheemulsionexplosivesweremeasuredbyusingtheshortingpinsinthe casesofdifferentchargecross-sectionalareasanddifferentchargecurvatures.Andtheinfluencesof thechargediametersandthechargecurvaturesonthedetonationpropagationvelocitiesintheemulsionexplosiveswereanalyzed. Itisshownthatthedetonationvelocitiesdecreaselinearlywiththedecreasingofthechargecurvatureradiiandthechargediametersquare. Whenthechargediameteror thecurvatureradiusreducesbelowacertaincriticalvalue,thedetonationreactionceases.Basedon theexperimentaldata,anempiricalformulawasproposedforcalculatingthedetonationvelocityofthe emulsionexplosivesintheconditionthatthecurvatureradiusandthechargediameterweregiven.
Theemulsionexplosiveswerechargedintothecurvedgroovemachinedonanironplate. Thedetonationvelocitiesoftheemulsionexplosivesweremeasuredbyusingtheshortingpinsinthe casesofdifferentchargecross-sectionalareasanddifferentchargecurvatures.Andtheinfluencesof thechargediametersandthechargecurvaturesonthedetonationpropagationvelocitiesintheemulsionexplosiveswereanalyzed. Itisshownthatthedetonationvelocitiesdecreaselinearlywiththedecreasingofthechargecurvatureradiiandthechargediametersquare. Whenthechargediameteror thecurvatureradiusreducesbelowacertaincriticalvalue,thedetonationreactionceases.Basedon theexperimentaldata,anempiricalformulawasproposedforcalculatingthedetonationvelocityofthe emulsionexplosivesintheconditionthatthecurvatureradiusandthechargediameterweregiven.
Experimentalstudyonpremixedflammablegasexplosionventing
inlinkedvesselsunderthesameeffictiveventarea
2012, 32(2): 221-224.
doi: 10.11883/1001-1455(2012)02-0221-04
Abstract:
Explosionventingwascarriedoutinbothlinkedandsinglevesselsunderthesamedimensionlesseffectiveventareaconditionstostudyflamepropa ationandexplosionpressureevolution.It isshownthatthemaximumreducedexplosionpressureandthemaximumpressureriserateinthe linkedvesselsexceedthoseinthesinglevessels,especially,thedifferenceofthemaximumpressure riseratesismuchgreaterbetweenthelinkedvesselsandthesinglevessels.Atthesamedimensionless effectiveventarea,themaximumreducedexplosionpressureinthereceivingvesselofthelinkedvessels, ishigherthanthatinthereleasingvessel.Whenthereceivingvesselissmallerthanthereleasing vessel,themaximumreducedexplosionpressureinthereceivingvesselismuchhigher.Withtheincreaseofthepipelength, themaximumreducedexplosionpressureinthereceivingvesselincreases, andthemaximumreducedexplosionpressureinthereleasingvesselchangesunconspicuously.During theexplosionventinginthelinkedvessels,theflamepropagatesaccelerativelyinthepipe.Andatthe samepipelengths,theflamepropagationspeedfromasmallvesseltoabigvesselishigherthanthat fromabigvesseltoasmallvessel.
Explosionventingwascarriedoutinbothlinkedandsinglevesselsunderthesamedimensionlesseffectiveventareaconditionstostudyflamepropa ationandexplosionpressureevolution.It isshownthatthemaximumreducedexplosionpressureandthemaximumpressureriserateinthe linkedvesselsexceedthoseinthesinglevessels,especially,thedifferenceofthemaximumpressure riseratesismuchgreaterbetweenthelinkedvesselsandthesinglevessels.Atthesamedimensionless effectiveventarea,themaximumreducedexplosionpressureinthereceivingvesselofthelinkedvessels, ishigherthanthatinthereleasingvessel.Whenthereceivingvesselissmallerthanthereleasing vessel,themaximumreducedexplosionpressureinthereceivingvesselismuchhigher.Withtheincreaseofthepipelength, themaximumreducedexplosionpressureinthereceivingvesselincreases, andthemaximumreducedexplosionpressureinthereleasingvesselchangesunconspicuously.During theexplosionventinginthelinkedvessels,theflamepropagatesaccelerativelyinthepipe.Andatthe samepipelengths,theflamepropagationspeedfromasmallvesseltoabigvesselishigherthanthat fromabigvesseltoasmallvessel.
