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37 个结果
  • 简介:ThispaperpresentsaclosedformsolutionandnumericalanalysisforEshelby’sellipticinclusioninaninfiniteplate.Thecomplexvariablemethodandtheconformalmappingtechniqueareused.Thecontinuityconditionsforthetractionanddisplacementalongtheinterfaceinthephysicalplanearereducedtothesimilarconditionsalongtheunitcircleofthemappingplane.Thepropertiesofthecomplexpotentialsdefinedinthefiniteellipticregionareanalyzed.Fromthecontinuityconditions,onecanseparateandobtaintherelevantcomplexpotentialsdefinedintheinclusionandthematrix.Fromtheobtainedcomplexpotentials,thedependenceoftherealstrainsandstressesintheinclusionfromtheassumedeigenstrainsisevaluated.Inaddition,thestressdistributionontheinterfacealongthematrixsideisevaluated.Theresultsareobtainedinthepaperforthefirsttime.

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  • 简介:Afewadditionaldatafromourpreviousexperimentswereplottedtoemphasizetheshear-thickeningbehaviorofdeoxysickleerythrocyte(SS)suspension.Aconstitutiveequation(namedasFXequation)wasdevelopedandappliedtoacylindricalpipeflowofashear-thickeningfluid.Abluntvelocityprofileanditsvolumeflowratewerecalculated.Theflowwasnon-viscous(potential)inthecentralpartofthepipe(i.e.thecentralcoreorthecentralplug-flow),andbecamemoreandmoreviscoustowardsthewallofthepipeafteraspecificradialdistance,whichwasdeterminedbyacriticalshearrateofγF(namedasFung'sshearrate).Furthermore,combiningtheFXequationwiththeoriginalCasson'sequation,theauthorobtainedamodifiedCasson'sequationbyintroducingγF.

  • 标签: CASSON方程 剪切率 FX方程 悬浮液 粘性流体力学
  • 简介:Whenanaircraftishoveringordoingadive-hikeflightatafixedspeed,aconstantadditionalinertialforcewillbeinducedtotherotorsystemoftheaero-engine,whichcanbecalledaconstantmaneuverload.Takehoveringasanexample.AJeffcottrotorsystemwithabiasedrotorandseveralnonlinearelasticsupportsismodeled,andthevibrationcharacteristicsoftherotorsystemunderaconstantmaneuverloadareanalyticallystudied.Byusingthemultiple-scalemethod,thedifferentialequationsofthesystemaresolved,andthebifurcationequationsareobtained.Then,thebifurcationsofthesystemareanalyzedbyusingthesingularitytheoryforthetwovariables.IntheEG-plane,whereEreferstotheeccentricityoftherotorandGrepresentstheconstantmaneuverload,twohysteresispointsetsandonedoublelimitpointsetareobtained.Thebifurcationdiagramsarealsoplotted.Itisindicatedthattheresonanceregionsofthetwovariableswillshifttotherightwhentheaircraftismaneuvering.Furthermore,themovementalongthehorizontaldirectionisfasterthanthatalongtheverticaldirection.Thus,thedifferentoverlappingmodesofthetworesonanceregionswillbringaboutdifferentbifurcationmodesduetothenonlinearcouplingeffects.Thisresultlaysatheoreticalfoundationforcontrollingthestabilityoftheaero-engine’srotorsystemunderamaneuverload.

  • 标签: 航空发动机 转子系统 分岔分析 动载荷 恒定 非线性弹性支承
  • 简介:Wavepropagationanalysisforafunctionallygradednanobeamwithrectangularcross-sectionrestingonvisco-Pasternak'sfoundationisstudiedinthispaper.Timoshenko'sbeammodelandnonlocalelasticitytheoryareemployedforformulationoftheproblem.TheequationsofmotionarederivedusingHamilton'sprincipalsbycalculatingkineticenergy,strainenergyandworkduetoviscoelasticfoundation.Theeffectsofvariousparameterssuchaswavenumber,non-homogeneousindex,nonlocalparameterandthreeparametersoffoundationareperformedonthephasevelocityofthenanobeam.Theobtainedresultsindicatethatsomeparameterssuchasnon-homogeneousindex,nonlocalparameterandwavenumberhavesignificanteffectontheresponseofthesystem.

  • 标签: 弹性波传播 功能梯度 基础 TIMOSHENKO 非局部弹性理论
  • 简介:Head-oncollisionbetweentwohydroelasticsolitarywavespropagatingatthesurfaceofanincompressibleandidealfluidcoveredbyathinicesheetisanalyticallystudiedbymeansofasingularperturbationmethod.TheicesheetisrepresentedbythePlotnikov-TolandmodelwiththehelpofthespecialCosserattheoryofhyperelasticshellsandtheKirchhoff-Loveplatetheory,whichyieldsthenonlinearandconservativeexpressionforthebendingforces.TheshallowwaterassumptionistakenforthefluidmotionwiththeBoussinesqapproximation.TheresultinggoverningequationsaresolvedasymptoticallywiththeaidofthePoincar-Lighthill-Kuomethod,andthesolutionsuptothethirdorderareexplicitlypresented.Itisobservedthatsolitarywavesaftercollisiondonotchangetheirshapesandamplitudes.Thewaveprofileissymmetricbeforecollision,anditbecomes,aftercollision,unsymmetricandtitledbackwardinthedirectionofwavepropagation.Thewaveprofilesignificantlyreducesduetogreaterimpactsofelasticplateandsurfacetension.Agraphicalcomparisonispresentedwithpublishedresults,andthegraphicalcomparisonbetweenlinearandnonlinearelasticplatemodelsisalsoshownasaspecialcaseofourstudy.

  • 标签: Head-on COLLISION Hydroelastic SOLITARY WAVES ICE
  • 简介:AmethodoflocalizationisproposedtolowerthehighorderofequationsinFEMcalcula-tionforthestabilityofacomplexthin-walledstructure.Thelocalizedanalysisenablesustoobtainboththeupperandlowerlimitsforthebifurcatingpointinawholelinearelasticstructuralsystem,aswellasanap-proximatesolutiontoasymptoticpost-bucklingproblem.Somenumericalexamplesareincluded.

  • 标签: BUCKLING of a THIN-WALLED structure LOCALIZED
  • 简介:IntroductionThesubtropicalanticyclone(subtropicalhigh)overEast_Asiaregionisanimportantsynopticsysteminfluencingthisregion’swe...

  • 标签: SUBTROPICAL ANTICYCLONE potential ENSTROPHY stability criterion
  • 简介:Thispapergeneralizesthesingle-shellKidder'sself-similarsolutiontothedouble-shellonewithadiscontinuityindensityacrosstheinterface.AnisentropicimplosionmodelisconstructedtostudytheRayleigh-Taylorinstabilityfortheimplosioncompression,AGodunov-typemethodintheLagrangiancoordinatesisusedtocomputetheone-dimensionalEulerequationwiththeinitialandboundaryconditionsforthedouble-shellKidder'sself-similarsolutioninsphericalgeometry.Numericalresultsareobtainedtovalidatethedouble-shellimplosionmodel.Byprogrammingandusingthelinearperturbationcodes,alinearstabilityanalysisontheRayleigh-Taylorinstabilityforthedouble-shellisentropicimplosionmodelisperformed.Itisfoundthat,whentheinitialperturbationisconcentratedmuchclosertotheinterfaceofthetwoshells,orwhenthesphericalwavenumberbecomesmuchsmaller,themodalradiusoftheinterfacegrowsmuchfaster,i.e.,moreunstable.Inaddition,fromthespatialpointofviewforthecompressibilityeffectontheperturbationevolution,thecompressibilityoftheoutershellhasadestabilizationeffectontheRayleigh-Taylorinstability,whilethecompressibilityoftheinnershellhasastabilizationeffect.

  • 标签: 不稳定性分析 自相似解 线性扰动 双壳 Rayleigh Taylor
  • 简介:pearlitic钢与随机的取向由众多的pearlitic殖民地组成,并且每个殖民地由铁酸盐和渗碳体的许多平行薄片组成。这种材料的组成的行为可以包含两固有的anisotropy,塑料变丑导致anisotropy。对为这种双阶段的材料的周期的粘性的描述被一个基于微观结构的组成的模型的使用为一个pearlitic殖民地,和山为椭圆体的包括合并各向异性的Eshelby张肌的前後一致的计划建议。相应数字算法被开发。pearlitic钢BS11和单相的冷抽的铜的回答使遭到了到一相称性地周期的装载被分析。分析结果与试验性的同意很好。与用各向同性的Eshelby张肌的结果相比,各向同性的近似能以一个简单得多的方法提供可接受的全面回答,这被显示出。

  • 标签: 珠光体钢 各向异性张量 循环塑性 微观结构
  • 简介:DrivenbycuriosityaboutpossibleflightoptionsfortheChang’e-2spacecraftafteritremainsattheSun-EarthL2point,effectiveapproachesweredevelopedfordesigningpreliminaryfuel-optimalnear-Earthasteroidflybytrajectories.Theapproachesincludetheuseofmodifiedunstablemanifolds,gridsearchofthemanifolds’parameters,andatwo-impulsemaneuverfororbitalphasematchingandz-axisbiaschange,andaredemonstratedtobeeffectiveinasteroidtargetscreeningandtrajectoryoptimization.Asteroidflybysareexpectedtobewithinadistanceof2×107kmfromtheEarthowingtotheconstrainedEarth-spacecraftcommunicationrange.Inthiscase,thespacecraft’sorbitalmotionissignificantlyaffectedbythegravitiesofboththeSunandtheEarth,andtherefore,theconceptofthe"heliocentricoscillating-Keplerorbit"isproposed,becausetheclassicalorbitalelementsoftheflybytrajectoriesreferencedintheheliocentricinertialframeoscillatesignificantlywithrespecttotime.Theanalysisandresultspresentedinthisstudyshowthat,amongtheasteroidswhoseorbitsarethemostaccuratelypredicted,"Toutatis","2005NZ6",or"2010CL19"mightbeencounteredbyChang’e-2inlate2012or2013withtotalimpulseslessthan100m/s.

  • 标签: 近地小行星 飞行轨迹 地球 太阳 轨道运动 不稳定流形
  • 简介:Dispersionofmulti-walledcarbonnanotubesinpoly(p-phenylene)compositeexposedtotoluenewasexperimentallyinvestigated.3mgofmulti-walledcarbonnanotubeswithnominalsizeof20nmwascompoundedwith30mgofpoly(p-phenylene)withthepresenceofterpineolasbindinginitiator.Toinvestigateanoptimalconditionforhomogenizingallconstituents,ultrasonicationwithanoutputpowerof750Wwasemployedwithcompoundingtimeof3,10,20and30min.WithFTIRanalyses,itcouldbeconfirmedthathomogeneouscompositeofmulti-walledcarbonnanotubesandpoly(p-phenylene)couldbeprepared.SEManalyseswerealsoconductedtoexaminethedispersionofmulti-walledcarbonnanotubesinthepolymermatrix.Thenintrinsicelectricalresistanceofthecompositesafterbeingexposedtotoluenewasalsoinvestigated.Itwasfoundthatthecompositefilmpreparedwithultrasonicationfor20mincouldprovidesufficientlysensitiveresponsewithrespecttovariedconcentrationoftoluene.

  • 标签: 多壁碳纳米管 多分散 甲苯 电气特性 薄膜 复合材料