2013 Vol. 33, No. 3
Display Method:
2013, 33(3): 225-230.
doi: 10.11883/1001-1455(2013)03-0225-06
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Abstract:
Tungsten structure reinforced composites are materials that the tungsten structure is embedded into the metallic glass to prevent the shear bands from developing in the metallic glass. In order to expand their application and understand their mechanical properties, dynamic compression tests were performed for two Zr-based metallic glass composites reinforced by tungsten fiber and porous tungsten, respectively, by using a SHPB device at three different temperatures and various strain rates. Comparison of the dynamic mechanical properties between the two composites reveals that they both have considerable stain rate sensitivity and excellent plastic deformation ability, but they have different deformation mechanisms. The deformation of the tungsten fiber reinforced Zr-based metallic glass composite is due to the local structure instability or thermal instability of tungsten fibers. And this phenomenon was numerically simulated. On the other hand, the loading of the porous tungsten reinforced Zr-based metallic glass composite at the beginning is mainly carried by tungsten skeleton rather than the combined action of the components, which makes the yield stress of the porous tungsten reinforced composite smaller than those of both pure Zr-based metallic glass and pure tungsten.
Tungsten structure reinforced composites are materials that the tungsten structure is embedded into the metallic glass to prevent the shear bands from developing in the metallic glass. In order to expand their application and understand their mechanical properties, dynamic compression tests were performed for two Zr-based metallic glass composites reinforced by tungsten fiber and porous tungsten, respectively, by using a SHPB device at three different temperatures and various strain rates. Comparison of the dynamic mechanical properties between the two composites reveals that they both have considerable stain rate sensitivity and excellent plastic deformation ability, but they have different deformation mechanisms. The deformation of the tungsten fiber reinforced Zr-based metallic glass composite is due to the local structure instability or thermal instability of tungsten fibers. And this phenomenon was numerically simulated. On the other hand, the loading of the porous tungsten reinforced Zr-based metallic glass composite at the beginning is mainly carried by tungsten skeleton rather than the combined action of the components, which makes the yield stress of the porous tungsten reinforced composite smaller than those of both pure Zr-based metallic glass and pure tungsten.
2013, 33(3): 231-037.
doi: 10.11883/1001-1455(2013)03-0231-07
Abstract:
A computational inverse technique is presented for determining the detonator status in an underground explosion from the given damage effects. In this technique, the detonator status can be determined by minimizing the error functions formulated using the given damage effects and those computed using the forward solvers based on the candidates of the detonator statuses. To reduce the computational cost, the polynomial approximation model based on error reduction ratio is used to replace the actual computational model. The nonlinear Newtons method is employed as the inverse procedure. In order to improve the computational efficiency, the trust region method is adopted to manage the error between the approximation model and the actual one. Additionally, the Tikhonov regularization method is applied to the ill-posed problems. The results demonstrate that the detonator status can be determined from the given damage effects with high efficiency through innovative use of the present method.
A computational inverse technique is presented for determining the detonator status in an underground explosion from the given damage effects. In this technique, the detonator status can be determined by minimizing the error functions formulated using the given damage effects and those computed using the forward solvers based on the candidates of the detonator statuses. To reduce the computational cost, the polynomial approximation model based on error reduction ratio is used to replace the actual computational model. The nonlinear Newtons method is employed as the inverse procedure. In order to improve the computational efficiency, the trust region method is adopted to manage the error between the approximation model and the actual one. Additionally, the Tikhonov regularization method is applied to the ill-posed problems. The results demonstrate that the detonator status can be determined from the given damage effects with high efficiency through innovative use of the present method.
2013, 33(3): 238-242.
doi: 10.11883/1001-1455(2013)03-0238-05
Abstract:
To reveal the sensitivity of strength and fracture toughness to loading rate for ultra-strength steel 18NiC250, the plastic flow stress-strain curves of 18NiC250 were measured in the strain-rate range from 0.001 s-1 to 2 000 s-1 and its fracture toughness was obtained in the loading-rate range from 10-1 MPam1/2/s to 106 MPam1/2/s by using a CSS4410 test machine and a SHPB system. And the fracture failure mechanism of 18NiC250 was discussed by fractography and Taylor experiment. Results show that the flow stress of 18NiC250 is not sensitive to loading rate and it can remain 1.9 GPa. But the fracture toughness of 18NiC250 is quite sensitive to loading rate, it decreases by 38.2% when the loading rate increases from 10-1 MPam1/2/s to 106 MPam1/2/s, and the corresponding fracture mode changes from ductile dimple to cleavage.
To reveal the sensitivity of strength and fracture toughness to loading rate for ultra-strength steel 18NiC250, the plastic flow stress-strain curves of 18NiC250 were measured in the strain-rate range from 0.001 s-1 to 2 000 s-1 and its fracture toughness was obtained in the loading-rate range from 10-1 MPam1/2/s to 106 MPam1/2/s by using a CSS4410 test machine and a SHPB system. And the fracture failure mechanism of 18NiC250 was discussed by fractography and Taylor experiment. Results show that the flow stress of 18NiC250 is not sensitive to loading rate and it can remain 1.9 GPa. But the fracture toughness of 18NiC250 is quite sensitive to loading rate, it decreases by 38.2% when the loading rate increases from 10-1 MPam1/2/s to 106 MPam1/2/s, and the corresponding fracture mode changes from ductile dimple to cleavage.
2013, 33(3): 243-248.
doi: 10.11883/1001-1455(2013)03-0243-06
Abstract:
By taking a large airport engineering as an example, the damages to early-age concretes under blasting vibration were experimentally investigated. Pendulum experiments were carried out on the C30 plain concrete cubic specimens at different ages. And the uniaxial compression experiments were conducted on the two groups of concrete cubic specimens, which were subjected to the same impact loads at the same ages, at 18 and 28 days of the same water curing, respectively. The corresponding uniaxial compressive strengths were measured. The results show that the curing time can affect the uniaxial compressive strengths of early-age concretes exposed to blasting vibration and blasting vibration can more obviously decrease the uniaxial compressive strengths of 3-5 days old concretes. Based on the above experimental results, the compressive strength evolution of early-age concretes subjected to blasting vibration at different curing ages was revealed by combining with the site test and the numerical simulation. And the security technology indexes were proposed for large engineering construction projects consisting of concreting and blasting.
By taking a large airport engineering as an example, the damages to early-age concretes under blasting vibration were experimentally investigated. Pendulum experiments were carried out on the C30 plain concrete cubic specimens at different ages. And the uniaxial compression experiments were conducted on the two groups of concrete cubic specimens, which were subjected to the same impact loads at the same ages, at 18 and 28 days of the same water curing, respectively. The corresponding uniaxial compressive strengths were measured. The results show that the curing time can affect the uniaxial compressive strengths of early-age concretes exposed to blasting vibration and blasting vibration can more obviously decrease the uniaxial compressive strengths of 3-5 days old concretes. Based on the above experimental results, the compressive strength evolution of early-age concretes subjected to blasting vibration at different curing ages was revealed by combining with the site test and the numerical simulation. And the security technology indexes were proposed for large engineering construction projects consisting of concreting and blasting.
2013, 33(3): 249-254.
doi: 10.11883/1001-1455(2013)03-0249-06
Abstract:
Abstract:Inviewofthefactsthattheunlockingprocessofanexplosiveboltisinstantaneous,theexplosiveboltcanundergoalargedeformationinthisprocess, andtheimpedancesofthematerialsin theinterfacehavegreatvarianceinthecourseofthecontactexplosion,basedontheSPH methodconsideringmaterialsstrength, thegoverningequationistransformedtoaformwhichcanreducetheinfluencesofparticledensityandmassontheprocessofthephysicalquantityap roximation.Thena three-dimensionalSPH modelfortheexplosiveboltisbuilttostudytheimpactcharacteristicsinthe unlockingprocessoftheexplosivebolt.Besides,thecomputationalresultsarecomparedwiththe onescomputedbytheLS-DYNAsoftwaretoverifytheaccuracyofthemodelbuiltinthepaper
Abstract:Inviewofthefactsthattheunlockingprocessofanexplosiveboltisinstantaneous,theexplosiveboltcanundergoalargedeformationinthisprocess, andtheimpedancesofthematerialsin theinterfacehavegreatvarianceinthecourseofthecontactexplosion,basedontheSPH methodconsideringmaterialsstrength, thegoverningequationistransformedtoaformwhichcanreducetheinfluencesofparticledensityandmassontheprocessofthephysicalquantityap roximation.Thena three-dimensionalSPH modelfortheexplosiveboltisbuilttostudytheimpactcharacteristicsinthe unlockingprocessoftheexplosivebolt.Besides,thecomputationalresultsarecomparedwiththe onescomputedbytheLS-DYNAsoftwaretoverifytheaccuracyofthemodelbuiltinthepaper
2013, 33(3): 255-263.
doi: 10.11883/1001-1455(2013)03-0255-08
Abstract:
Thedynamicresponsesofstructuresunderblastloadingaremuchmorecomplicatedthan thoseunderotherloadingssuchasstaticandearthquakeloadings.Inordertofullyrealizetheblastresistancesofconcretegravitydams, agreatmanynumericalsimulationswereimplementedbyusing three-dimensionalnonlinearfiniteelementmodels.Theinfluencesofdamheightandwaterlevelbeforethedamsontheblastresistanceofthedamswereanalyzed, andatheoreticalbasiswasprovided forantiknockperformanceevaluationandprotectiondesign.Strainrateeffectsofconcretedamswere takenintoconsiderationintheestablishmentofthefully-coupledmodelforthegravitydams.Forthis kindofconcretegravitydams,numericalresultsindicatethattheblastresistanceofthelowdamsis weakerthanthatofthehighdams,thatthewaterlevelbeforethedamsplaysanimportantroleonthe antiknockperformancesofthedams,andthattheantiknockperformancesofthedamscanbeeffectivelyimprovedbyreducingthewaterlevel.
Thedynamicresponsesofstructuresunderblastloadingaremuchmorecomplicatedthan thoseunderotherloadingssuchasstaticandearthquakeloadings.Inordertofullyrealizetheblastresistancesofconcretegravitydams, agreatmanynumericalsimulationswereimplementedbyusing three-dimensionalnonlinearfiniteelementmodels.Theinfluencesofdamheightandwaterlevelbeforethedamsontheblastresistanceofthedamswereanalyzed, andatheoreticalbasiswasprovided forantiknockperformanceevaluationandprotectiondesign.Strainrateeffectsofconcretedamswere takenintoconsiderationintheestablishmentofthefully-coupledmodelforthegravitydams.Forthis kindofconcretegravitydams,numericalresultsindicatethattheblastresistanceofthelowdamsis weakerthanthatofthehighdams,thatthewaterlevelbeforethedamsplaysanimportantroleonthe antiknockperformancesofthedams,andthattheantiknockperformancesofthedamscanbeeffectivelyimprovedbyreducingthewaterlevel.
2013, 33(3): 263-269.
doi: 10.11883/1001-1455(2013)03-0263-06
Abstract:
Thedouble-layeredthinA3steelplateswerenormallyimpactedbytheogival-,blunt-and hemispherical-nosedprojectileswiththehelpofagasguntoinvestigatetheinfluencesoflayerorder ontheballisticresistanceandfailuremodeofthetargets.Andtheresidualandinitialvelocitiesofthe projectilesweremeasuredandthecorrespondingballisticlimitvelocitieswereobtainedbyleastsquare fittingtheRecht-Ipsonformulatothemeasuredresidualandinitialvelocities.Theexperimentaldata revealthattheeffectsoflayerorderontheballisticresistancearedependentontheprojectilenose shapes.Fortheblunt-andhemispherical-nosedprojectiles,thedouble-layeredplateswithathick frontplateandathinbackplatecangivegreaterresistancethantheoneswiththeoppositelayering order.However,fortheogival-nosedprojectiles,thedouble-layeredplateswithathinfrontplateand athickbackplateexhibitgreaterresistancethantheoneswiththeoppositelayerorder.Theinfluencesoflayerorderontheballisticresistanceresultfromthetransitionofthefailuremodesandthe interferenceforcebetweendifferentconfigurationtargets.
Thedouble-layeredthinA3steelplateswerenormallyimpactedbytheogival-,blunt-and hemispherical-nosedprojectileswiththehelpofagasguntoinvestigatetheinfluencesoflayerorder ontheballisticresistanceandfailuremodeofthetargets.Andtheresidualandinitialvelocitiesofthe projectilesweremeasuredandthecorrespondingballisticlimitvelocitieswereobtainedbyleastsquare fittingtheRecht-Ipsonformulatothemeasuredresidualandinitialvelocities.Theexperimentaldata revealthattheeffectsoflayerorderontheballisticresistancearedependentontheprojectilenose shapes.Fortheblunt-andhemispherical-nosedprojectiles,thedouble-layeredplateswithathick frontplateandathinbackplatecangivegreaterresistancethantheoneswiththeoppositelayering order.However,fortheogival-nosedprojectiles,thedouble-layeredplateswithathinfrontplateand athickbackplateexhibitgreaterresistancethantheoneswiththeoppositelayerorder.Theinfluencesoflayerorderontheballisticresistanceresultfromthetransitionofthefailuremodesandthe interferenceforcebetweendifferentconfigurationtargets.
2013, 33(3): 269-275.
doi: 10.11883/1001-1455(2013)03-0269-06
Abstract:
Basedonthesixbasicparametersincludingapparentdensity,mass,plateauload,out-ofplaneelasticmodulus, compressionratioandenergyabsorption,themappingrelationsweredeveloped betweenthethickness-lengthratiosofthehexagonalaluminumhoneycombcellsbeforeandaftermagnification. Thedevelopedmappingrelationsdisplaythatthecellularstructureswiththesamethickness- lengthratioshavethesamemechanicalandenergy-absorbingproperties.Bymagnifyingthecell geometricconfigurationsinlengthbutkeepingthesamethickness-lengthratiosatthesametimes,a newanalysisprocesswasputforwardfortheequivalentmagnificationofthealuminum honeycomb cellsfromcompactnesstosparseness.Basedontheaboveanalysisprocess,thetimecostinthenumericalsimulationforthehigh- densitycellularstructureswasdecreasedbyreducingthecellnumbers. Subsequently,eightnumericalmodelsat1-8timesmagnificationofthesamealuminumhoneycomb cellwerebuiltonthebasisoftheexplicitfiniteelementmethodandthesimulatedresultsbythem confirmedthevalidityoftheequivalentmethoddeveloped.Comparisonofthecomputedtimebefore andaftermagnificationshowsthehighefficiencyoftheequivalentmethod.Butwhenthetotalsizein theout-of-planedirectionisapproximatetothecelllength,theequivalentmethodislimited.
Basedonthesixbasicparametersincludingapparentdensity,mass,plateauload,out-ofplaneelasticmodulus, compressionratioandenergyabsorption,themappingrelationsweredeveloped betweenthethickness-lengthratiosofthehexagonalaluminumhoneycombcellsbeforeandaftermagnification. Thedevelopedmappingrelationsdisplaythatthecellularstructureswiththesamethickness- lengthratioshavethesamemechanicalandenergy-absorbingproperties.Bymagnifyingthecell geometricconfigurationsinlengthbutkeepingthesamethickness-lengthratiosatthesametimes,a newanalysisprocesswasputforwardfortheequivalentmagnificationofthealuminum honeycomb cellsfromcompactnesstosparseness.Basedontheaboveanalysisprocess,thetimecostinthenumericalsimulationforthehigh- densitycellularstructureswasdecreasedbyreducingthecellnumbers. Subsequently,eightnumericalmodelsat1-8timesmagnificationofthesamealuminumhoneycomb cellwerebuiltonthebasisoftheexplicitfiniteelementmethodandthesimulatedresultsbythem confirmedthevalidityoftheequivalentmethoddeveloped.Comparisonofthecomputedtimebefore andaftermagnificationshowsthehighefficiencyoftheequivalentmethod.Butwhenthetotalsizein theout-of-planedirectionisapproximatetothecelllength,theequivalentmethodislimited.
2013, 33(3): 275-282.
doi: 10.11883/1001-1455(2013)03-0275-07
Abstract:
Dynamicsplittingexperimentsoncementmortarspecimenswereperformedtoexperimentallyinvestigatethecrackinitiationandpropagationunde variousloadingrates.Andamicro-mechanicalmodelwasdevelopedtodeeplyanalyzethisproblem. Theresultsdemonstratethatthemicrocrackinertiaisoneofthemechanismsresponsiblefortheincreaseofdynamictensilestrengthwith strainratewhichcanbeobservedinthedynamictensileexperimentsonconcrete-likematerials
Dynamicsplittingexperimentsoncementmortarspecimenswereperformedtoexperimentallyinvestigatethecrackinitiationandpropagationunde variousloadingrates.Andamicro-mechanicalmodelwasdevelopedtodeeplyanalyzethisproblem. Theresultsdemonstratethatthemicrocrackinertiaisoneofthemechanismsresponsiblefortheincreaseofdynamictensilestrengthwith strainratewhichcanbeobservedinthedynamictensileexperimentsonconcrete-likematerials
2013, 33(3): 282-286.
doi: 10.11883/1001-1455(2013)03-0282-05
Abstract:
WemodifytheinaccurateformulasusedinBurgesssresistivitymodel(BRM)andhisalgorithmflow, andcalculatetheelectricalresistivityofthemetalsaluminum,copper,tungsten,stainlesssteel, goldandsilver.ThecalculatedresultsareconsistentwiththeonesbyBurgess.Amagnetohydrodynamicmodelisproposedtosimulatethemagnetically- acceleratedflyerplateexperimentperformedontheZmachineatSandiaNationalLaboratories. Thecomputedfree-surfacevelocitiesofthe flyerplateswithBRMdonotagreewellwiththeexperimentalrecordsbyVISAR.Astheliquidreachesthevaporizationpoint, theliquidbecomesthegas-liquidmixture,sothegas-liquidmixtureresistivitymodel( GLMRM)shouldbeusedinthetemperaturerangefromthevaporizationpointtothe criticaltemperatureandthegasphaseresistivitymodelisnotappropriateinthistemperatureregion. Thesimulatedfree-surfacevelocitiesoftheflyerplatewithGLMRMcoincidewiththeexperimental resultsandthesimulationresultsbyALEGRAcode.
WemodifytheinaccurateformulasusedinBurgesssresistivitymodel(BRM)andhisalgorithmflow, andcalculatetheelectricalresistivityofthemetalsaluminum,copper,tungsten,stainlesssteel, goldandsilver.ThecalculatedresultsareconsistentwiththeonesbyBurgess.Amagnetohydrodynamicmodelisproposedtosimulatethemagnetically- acceleratedflyerplateexperimentperformedontheZmachineatSandiaNationalLaboratories. Thecomputedfree-surfacevelocitiesofthe flyerplateswithBRMdonotagreewellwiththeexperimentalrecordsbyVISAR.Astheliquidreachesthevaporizationpoint, theliquidbecomesthegas-liquidmixture,sothegas-liquidmixtureresistivitymodel( GLMRM)shouldbeusedinthetemperaturerangefromthevaporizationpointtothe criticaltemperatureandthegasphaseresistivitymodelisnotappropriateinthistemperatureregion. Thesimulatedfree-surfacevelocitiesoftheflyerplatewithGLMRMcoincidewiththeexperimental resultsandthesimulationresultsbyALEGRAcode.
2013, 33(3): 287-292.
doi: 10.11883/1001-1455(2013)03-0287-05
Abstract:
Torealizethathunkfraisescanbefastperforatedandtheperforateddepthandwidthareenough, anewtandemshapedchargestructurewasproposedbyusingtwosamestructuresofexplosively- formedprojectile(EFP)shapedcharges.Andtheeffectsofthestructuralparametersonthe tandemEFPchargepenetrationpowerwereanalyzed.Basedontheaboveanalysis,experimentswere conductedfortandemEFPspenetrating45steeltargetsunderdifferentchargespacingsanddifferent initiationdelays,respectively.TheresultsshowthatthetandemEFPchargestructurecangreatlyimprovethepenetrationefficiencyofthetwo- stagetandemshapedchargeanditcanbeusedtoeffectively penetratehardobjects.
Torealizethathunkfraisescanbefastperforatedandtheperforateddepthandwidthareenough, anewtandemshapedchargestructurewasproposedbyusingtwosamestructuresofexplosively- formedprojectile(EFP)shapedcharges.Andtheeffectsofthestructuralparametersonthe tandemEFPchargepenetrationpowerwereanalyzed.Basedontheaboveanalysis,experimentswere conductedfortandemEFPspenetrating45steeltargetsunderdifferentchargespacingsanddifferent initiationdelays,respectively.TheresultsshowthatthetandemEFPchargestructurecangreatlyimprovethepenetrationefficiencyofthetwo- stagetandemshapedchargeanditcanbeusedtoeffectively penetratehardobjects.
2013, 33(3): 292-297.
doi: 10.11883/1001-1455(2013)03-0292-05
Abstract:
Abstract:Byanalyzingtherelationshipsbetweentheshapeparametersofpropellantgrainandthe pressure-timecurveinaclosedbomb,acomputationalmethodwasestablishedforestimatingthe shapecharacteristicparametersoffracturedpropellantingrainformandthedetailedcalculationsteps weregiven.Thepropellantswithdifferentfracturedegreesobtainedindropweighttestsweretested inaclosebombandthecorrespondingshapecharacteristicparameterswerecalculatedbyusingtheestablishedmethod. Thecalculatedresultsareinagreementwiththeexperimentalones.
Abstract:Byanalyzingtherelationshipsbetweentheshapeparametersofpropellantgrainandthe pressure-timecurveinaclosedbomb,acomputationalmethodwasestablishedforestimatingthe shapecharacteristicparametersoffracturedpropellantingrainformandthedetailedcalculationsteps weregiven.Thepropellantswithdifferentfracturedegreesobtainedindropweighttestsweretested inaclosebombandthecorrespondingshapecharacteristicparameterswerecalculatedbyusingtheestablishedmethod. Thecalculatedresultsareinagreementwiththeexperimentalones.
2013, 33(3): 297-303.
doi: 10.11883/1001-1455(2013)03-0297-06
Abstract:
Basedontheexistentinvestigationsthatthemainfailurepatternofanthraciteunderuniaxial impactloadingisthecombineddamageoftensilestressdamage,extensiblestraindamageandunloadingdamage, butcompression-shearingdamageisinfrequent,acompression-extension-tensiondamagemodelwasproposedtoanalyzetheimpact- inducedfractureinanthracite.Andaccordingtotheenergybalanceprincipleandthefracturetheory, thetheoreticalformulaforcalculationofthedynamic strengthintheproposedmodelwasdeducedtodeterminethequantitativerelationshipbetweentherelateddynamicparametersofanthracite. Aseriesofcompressivestrengthsofanthracitewerecalculatedbythededucedformula. Comparisonsshowthatthecalculatedresultsareinagreementwiththe existentmeasuredones.Sothededucedformulacanbeusedtoestimatetheextremestrengthofanthraciteunderuniaxialimpactloadinganditcanrevealthedamagemechanism fanthracite-likeporousmediaunderimpactloading.
Basedontheexistentinvestigationsthatthemainfailurepatternofanthraciteunderuniaxial impactloadingisthecombineddamageoftensilestressdamage,extensiblestraindamageandunloadingdamage, butcompression-shearingdamageisinfrequent,acompression-extension-tensiondamagemodelwasproposedtoanalyzetheimpact- inducedfractureinanthracite.Andaccordingtotheenergybalanceprincipleandthefracturetheory, thetheoreticalformulaforcalculationofthedynamic strengthintheproposedmodelwasdeducedtodeterminethequantitativerelationshipbetweentherelateddynamicparametersofanthracite. Aseriesofcompressivestrengthsofanthracitewerecalculatedbythededucedformula. Comparisonsshowthatthecalculatedresultsareinagreementwiththe existentmeasuredones.Sothededucedformulacanbeusedtoestimatetheextremestrengthofanthraciteunderuniaxialimpactloadinganditcanrevealthedamagemechanism fanthracite-likeporousmediaunderimpactloading.
2013, 33(3): 303-311.
doi: 10.11883/1001-1455(2013)03-0303-08
Abstract:
Thedamageinthecarbonfiber-reinforcedaluminumlaminates(CARALs)underlow-velocityimpactwasnumericallyanalyzedbyusingthethree- dimensionaldynamicfiniteelementsoftware, ABAQUS.ParticularattentionwaspaidonthedynamicresponseoftheCARALstolow-velocityimpact. Andcaseanalyseswereconductedandcomparedwiththeexistentresultstoverifythecorrectnessoftheabovemethod. TheimpactresistancesoftheCARALswerediscussedfromthematrix damage,debondingandenergyabsorptionandcomparedwiththoseofthetraditionaluminumsheets. TheresultsdisplaythattheCARALshavebetterimpactresistances.
Thedamageinthecarbonfiber-reinforcedaluminumlaminates(CARALs)underlow-velocityimpactwasnumericallyanalyzedbyusingthethree- dimensionaldynamicfiniteelementsoftware, ABAQUS.ParticularattentionwaspaidonthedynamicresponseoftheCARALstolow-velocityimpact. Andcaseanalyseswereconductedandcomparedwiththeexistentresultstoverifythecorrectnessoftheabovemethod. TheimpactresistancesoftheCARALswerediscussedfromthematrix damage,debondingandenergyabsorptionandcomparedwiththoseofthetraditionaluminumsheets. TheresultsdisplaythattheCARALshavebetterimpactresistances.
2013, 33(3): 311-315.
doi: 10.11883/1001-1455(2013)03-0311-04
Abstract:
Basedonthecalculationsonthepowderedaluminumpressureandtemperaturerelaxation timesinthedetonationzone,theconventionalCJmodelwasimprovedtoproposeanew multiphase flow modelbyconsideringthemultiphasedetonationproductsaswellasthethermaldisequilibriumin them.Theproposedmodelwasappliedtocalculatethedetonationvelocitiesofseveralaluminizedexplosives. Thecalculatedresultswerecomparedwiththeexistentexperimentalones.Andthecorrespondingerrorislessthan2%. Sothecalculatedresultsbythenew modelarebetterthanthoseby theconventionalCJmodel.
Basedonthecalculationsonthepowderedaluminumpressureandtemperaturerelaxation timesinthedetonationzone,theconventionalCJmodelwasimprovedtoproposeanew multiphase flow modelbyconsideringthemultiphasedetonationproductsaswellasthethermaldisequilibriumin them.Theproposedmodelwasappliedtocalculatethedetonationvelocitiesofseveralaluminizedexplosives. Thecalculatedresultswerecomparedwiththeexistentexperimentalones.Andthecorrespondingerrorislessthan2%. Sothecalculatedresultsbythenew modelarebetterthanthoseby theconventionalCJmodel.
2013, 33(3): 315-321.
doi: 10.11883/1001-1455(2013)03-0315-06
Abstract:
Asimplifiedthree-dimensionalfiniteelementmodelforhumanthoraxeswasestablishedand thepropermaterialmodelsandparameterswereselectedforthedifferentthoraxorgans.Themechanicalinteractionoftheblastwavesandthethoraxwasexploredbytheself- developedlocal-planewave methodbasedonLS-DYNA.Accordingtothespeeddifferencesbetweenthedifferentorgans,the traumadistributionswerepredicted.Thetraumadistributionsofthelungorganswereanalyzedwith theaidofthevariationsofcompressive,tensileandshearstressesinthelungmodel.Thesimulated resultsareconsistentwiththeanatomyexperimentalresultsandthecalculatedresultsbytheInjury code.Sothemethodproposediseffectiveandprecisetosimulatethetraumacharacteristicsofhuman thoraxessubjectedtoblastshockwavesanditcanprovideaneffectiveapproachtotheresearcheson theblasttrauma.
Asimplifiedthree-dimensionalfiniteelementmodelforhumanthoraxeswasestablishedand thepropermaterialmodelsandparameterswereselectedforthedifferentthoraxorgans.Themechanicalinteractionoftheblastwavesandthethoraxwasexploredbytheself- developedlocal-planewave methodbasedonLS-DYNA.Accordingtothespeeddifferencesbetweenthedifferentorgans,the traumadistributionswerepredicted.Thetraumadistributionsofthelungorganswereanalyzedwith theaidofthevariationsofcompressive,tensileandshearstressesinthelungmodel.Thesimulated resultsareconsistentwiththeanatomyexperimentalresultsandthecalculatedresultsbytheInjury code.Sothemethodproposediseffectiveandprecisetosimulatethetraumacharacteristicsofhuman thoraxessubjectedtoblastshockwavesanditcanprovideaneffectiveapproachtotheresearcheson theblasttrauma.
2013, 33(3): 321-325.
doi: 10.11883/1001-1455(2013)03-0321-04
Abstract:
Abstract:AninversionswitchforinternalelectronicpressuregaugeswasdesignedbyusingMEMSaccelerometerMMA8453QandMSP430 MCU.Thereby,usingthedirectiondetectionfunctionofthe accelerometer,MCUreadsitsaccelerationthroughtheI2Cinterfaceandjudgeswhetherthetesteddeviceisinversed. Forthedesignedinversionswitch,manyinversetestswerecarriedoutbythesteppingmotorandthesuccessprobabilitywas100%, andtheimpactresistancewastestedbyadoptinga Hopkinsonbarsystem.Theresultsshowthattheinversionswitchcanstillworkaftertheimpactof 45000g.Sothedesignedinversionswitchcanbeappliedonhigh-gimpactoccasions.
Abstract:AninversionswitchforinternalelectronicpressuregaugeswasdesignedbyusingMEMSaccelerometerMMA8453QandMSP430 MCU.Thereby,usingthedirectiondetectionfunctionofthe accelerometer,MCUreadsitsaccelerationthroughtheI2Cinterfaceandjudgeswhetherthetesteddeviceisinversed. Forthedesignedinversionswitch,manyinversetestswerecarriedoutbythesteppingmotorandthesuccessprobabilitywas100%, andtheimpactresistancewastestedbyadoptinga Hopkinsonbarsystem.Theresultsshowthattheinversionswitchcanstillworkaftertheimpactof 45000g.Sothedesignedinversionswitchcanbeappliedonhigh-gimpactoccasions.
2013, 33(3): 325-330.
doi: 10.11883/1001-1455(2013)03-0325-05
Abstract:
Aseriesofexperimentswerecarriedouttoexploretheenergyoutputcharacteristicsofthe explosiveinthedifferentunderwaterboundaryconditions:freefield,waterbottom,nearwaterbottomandnearwatersurface. Theexperimentalresultsshowthatwhentheexplosiveisnearthewater bottomandsurface,theboundaryconditionsweaklyaffecttheexplosion-inducedshockwavesand stronglyinfluencethebubblepulsation.Whenthedistancefromtheexplosivetothewaterbottomis lessthanthemaximumradiusofthebubbles,theunderwaterexplosionoftheexplosivefailstoform anintegratedbubblepulsationresultedfromthewaterbottomboundary.Whenthedistancefromthe explosivetothewatersurfaceislessthanthemaximumradiusofthebubbles,theairbubblesoverflowthewatersurfaceandfailtoformthebubblepulsationpressure. Whenthedistancefromtheexplosivetothewatersurfaceis1- 1.5timesasgreatasthemaximumradiusofthebubbles,partialair bubblesoverflowthewatersurfaceandthecorrespondingbubblepulsationpressureislowerthanthat inducedbytheexplosioninthefreefield.Becauseoftheairbubblerisinginitsexpansionandcontractionprocesses, theinfluencedrangebythewatersurfaceonthebubblepulsationislargerthatbythe waterbottom.
Aseriesofexperimentswerecarriedouttoexploretheenergyoutputcharacteristicsofthe explosiveinthedifferentunderwaterboundaryconditions:freefield,waterbottom,nearwaterbottomandnearwatersurface. Theexperimentalresultsshowthatwhentheexplosiveisnearthewater bottomandsurface,theboundaryconditionsweaklyaffecttheexplosion-inducedshockwavesand stronglyinfluencethebubblepulsation.Whenthedistancefromtheexplosivetothewaterbottomis lessthanthemaximumradiusofthebubbles,theunderwaterexplosionoftheexplosivefailstoform anintegratedbubblepulsationresultedfromthewaterbottomboundary.Whenthedistancefromthe explosivetothewatersurfaceislessthanthemaximumradiusofthebubbles,theairbubblesoverflowthewatersurfaceandfailtoformthebubblepulsationpressure. Whenthedistancefromtheexplosivetothewatersurfaceis1- 1.5timesasgreatasthemaximumradiusofthebubbles,partialair bubblesoverflowthewatersurfaceandthecorrespondingbubblepulsationpressureislowerthanthat inducedbytheexplosioninthefreefield.Becauseoftheairbubblerisinginitsexpansionandcontractionprocesses, theinfluencedrangebythewatersurfaceonthebubblepulsationislargerthatbythe waterbottom.
2013, 33(3): 330-336.
doi: 10.11883/1001-1455(2013)03-0330-07
Abstract:
Thepressureattheinnerwalloftheexplosionvesselwasmeasuredbyusingthepressure barmethodtoinvestigatetheinfluencesofthechargeshapeontheblastloadinginthefieldnearthe explosivesource.Theexperimentalresultsdisplaythatthemaximumratioofthepeakandimpulseof thereflectedloadingintheradialdirectioninducedbythecylindricalchargewiththelengthequalto itsdiametertothatinducedbyanequivalentsphericalchargeislargerthantwo.Numericalresults, obtainedbythenumericalmodelwhichisvalidatedbytheexperimentalresults,revealthedifferences ofhydrostaticpressure,density,particlevelocityofblastloadingbetweenthetwochargesandthe changesofthedifferencesoverthescaleddistancefromtheblastcenter.
Thepressureattheinnerwalloftheexplosionvesselwasmeasuredbyusingthepressure barmethodtoinvestigatetheinfluencesofthechargeshapeontheblastloadinginthefieldnearthe explosivesource.Theexperimentalresultsdisplaythatthemaximumratioofthepeakandimpulseof thereflectedloadingintheradialdirectioninducedbythecylindricalchargewiththelengthequalto itsdiametertothatinducedbyanequivalentsphericalchargeislargerthantwo.Numericalresults, obtainedbythenumericalmodelwhichisvalidatedbytheexperimentalresults,revealthedifferences ofhydrostaticpressure,density,particlevelocityofblastloadingbetweenthetwochargesandthe changesofthedifferencesoverthescaleddistancefromtheblastcenter.
