学科分类
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9 个结果
  • 简介:Effectsofdepositionlayerpositionandnumber/densityonlocalbendingofathinfilmaresystematicallyinvestigated.Becausethedepositionlayerinteractswiththethinfilmattheinterfaceandthereisanoffsetbetweenthethinfilmneutralsurfaceandtheinterface,thedepositionlayergeneratesnotonlyaxialstressbutalsobendingmoment.Thebendingmomentinducesaninstantout-of-planedeflectionofthethinfilm,whichmayormaynotcausethesocalledlocalbending.Thedepositionlayerismodeledasalocalstressor,whoselocationanddensityaredemonstratedtobevitaltotheoccurrenceoflocalbending.Thethinfilmrestsonaviscouslayer,whichisgovernedbytheNavier-Stokesequationandbehaveslikeanelasticfoundationtoexerttransverseforcesonthethinfilm.Theunknownfeatureoftheaxialconstraintforcemakesthegoverningequationhighlynonlinearevenforthesmalldeflectioncase.Theconstraintforceandfilmtransversedeflectionaresolvediterativelythroughthegoverningequationandthedisplacementconstraintequationofimmovableedges.Thisresearchshowsthatinsomespecialcases,thedepositiondensityincreasedoesnotnecessarilyreducethelocalbending.Bycomparingthethinfilmdeflectionsofdifferentdepositionnumbersandpositions,wealsopresenttheguidelineofstrengtheningorsuppressingthelocalbending.

  • 标签: 薄膜表面 局部弯曲 粘性 轴向压力 挠度方程 交互界面
  • 简介:Anon-localcontinuummodelforstrain-softeningsimplytakingplasticstrainordamagevari-ableasanon-localvariableisderivedbyusingtheadditivedecompositionprincipleoffinitedeformationgra-dient.Atthesametime,variationalequations,theirfiniteelementformulationsandnumericalconvolutedintegrationalgorithmofthemodelincurrentconfigurationusuallycalledco-movingcoordinatesystemaregiven.Stabilityandconvergenceofthemodelareprovenbymeansoftheweakconvergencetheoremofgen-eralfunctionandtheconvolutedintegrationtheory.Mathematicalandphysicalpropertiesofthecharacteris-ticsizeformaterialorstructureareaccountedforwithinthecontextofastatisticalweightedorkernelfunc-tion,andwayisinvestigated.Numericalsimulationshowsthatthismodelissuitablefortoanalyzingdefor-mationlocalizationproblems.

  • 标签: NON-LOCAL model LOCALIZATION FINITE DEFORMATION NUMERICAL
  • 简介:最近的实验[1]在superelastic的导致压力的阶段转变揭示了宏观的领域模式的许多新现象多晶的NiTi试管在张力的装载期间。新现象与一个螺旋状的领域,到柱体的从螺旋的领域拓扑学转变,域前面分叉和领域模式的负担路径依赖的形成包括变丑不稳定性。在这份报纸,我们与nonconvex种类精力作为有弹性的连续统为多晶体建模[2]并且采用非局部的种类坡度精力说明散开的领域前面的精力。我们在由一个非局部的有限元素方法的张力的装载下面在试管模仿平衡领域模式和他们的进化(女性)。域模式的观察负担路径依赖和拓扑学转变由于试管系统的热力学的metastability,这被揭示。计算也证明试管墙厚度在领域模式上有重要效果:与固定材料性质和界面的精力密度,大试管墙厚度导致一个长、细长的螺旋状的领域并且圆柱域的前面的严重分叉。

  • 标签: 钛管 宏观 转化 二阶 建模 加载路径
  • 简介:Agroupoftheoreticalmodelshasbeendevelopedforanalyzingtransientdynamicre-sponsetofilledmetalliccylindricalshellsimpactedbyflat-nosedmissilesatnormalobliquityontheba-sisoftheanalogymodelingmethodofbeam-onfoundation.Itcanbeusedforsolvingtheglobaldefor-mationandthelocalfailureofcylindricalshellsintheimpactprocess.Theballisticlimitspeedandim-pactresponsehistoryhavebeencalculatedbythisgroupoftheoreticalmodels,andtheinnerpressureeffectontheballisticlimitspeedandsomeparametersarediscussedatlength.Thequantitativerela-tionshipbetweeninternalpressureandtheballisticlimitspeedandsomesignificantconclusionshavebeenobtained,whicharebasicallyidenticalwithpreviousexperimentalresults.

  • 标签: missiles FILLED METALLIC cylindrical SHELLS PERFORATION
  • 简介:这研究的目的是评估本地人爬象粗糙的颗粒的热那样的各种各样的微观结构的损坏影响了地区(CGHAZ),精细的热影响了地区(FGHAZ),intercritical热影响了作为类型IV区域知道的地区(ICHAZ),焊接金属,并且由小穿孔机(SP)基于P92(9Cr-2W)钢焊接的金属爬在600掳C的测试。另外,焊接分开决定最弱的本地人,微观结构在上的效果爬在P92钢的焊接的破裂行为被学习。从试验性的结果,FGHAZ和类型IV区域结果是P92焊接的很弱的本地部分。特别,TYPEIV区域显示出最大的排水量率并且与许多过了最短的破裂生活爬洞广泛地在大多数这个区域传播了。

  • 标签: 逆向蠕变 小冲孔蠕变 热影响区 空穴
  • 简介:Themechanismsofinterracialdebondingofparticlereinforcedtheologicalmaterialsarestudied.Basedonanenergycriterion,asimpleformulaoflocalcriticalstressforinterfacialdebondingisderivedandexpressedintermsoftheinterfacialenergy.Theparticlesizeeffectoninterfacedebond-ingcanthenbeanalyzedeasilyowingtothefactthatcriticalstressisinverselyproportionaltothesquarerootofparticleradius.BytakingPP/CaCO3systemasanexample,thepresentenergycriterioniscomparedwiththemechanicaldebondingcriterion,anditisfoundthatundertheconditionthatbondstrengthisequaltomatrixstrengthandparticleradiusnotover0.2μm,themechanicaldebondingcri-terioncanbeautomaticallysatisfiediftheenergycriterionissatisfied.Arelationbetweencriticaltimeandinterfaceenergyiscalculatedbyusingtheenergycriterion.Theinfluencesoftheparticlevolumefractionandtheparliclesize,theloadingrateandtherelaxationtimeofthematrixonthecriticaltimeofinterfacialdebondingarealsodiscussed.

  • 标签: PARTICLE REINFORCED RHEOLOGICAL MATERIALS interfacial DEBONDING
  • 简介:Basedontheporousmediatheoryandbytakingintoaccounttheeffectsoftheporefluidviscidity,energyexchangesduetotheadditionalthermalconductionandconvectionbetweensolidandfluidphases,amathematicalmodelforthedynamic-thermo-hydro-mechanicalcouplingofanon-localthermalequilibriumfluid-saturatedporousmedium,inwhichthetwoconstituentsareassumedtobeincompressibleandimmiscible,isestablishedundertheassumptionofsmalldeformationofthesolidphase,smallvelocityofthefluidphaseandsmalltemperaturechangesofthetwoconstituents.Themathematicalmodelofalocalthermalequilibriumfluid-saturatedporousmediumcanbeobtaineddirectlyfromtheaboveone.SeveralGurtin-typevariationalprinciples,especiallyHu-Washizutypevariationalprinciples,fortheinitialboundaryvalueproblemsofdynamicandquasi-staticresponsesarepresented.Itshouldbepointedoutthatthesevariationalprinciplescanbedegeneratedeasilyintothecaseofisothermalincompressiblefluid-saturatedelasticporousmedia,whichhavebeendiscussedpreviously.

  • 标签: 热局部热等效 热力学耦合 数学模型 变化原则 多孔介质
  • 简介:Inthispaper,thescatteringofharmonicantiplaneshearwavesbytwofinitecracksisstudiedusingthenon-localtheory.TheFouriertransformisappliedandamixedboundaryvalueprob-lemisformulated.Thenasetoftripleintegralequationsissolvedusinganewmethod,namelySchmidt’smethod,ThismethodismoreexactandmorereasonablethanEringen’sforsolvingthiskindofproblem.Theresultofthestressnearthecracktipwasobtained.Contrarytotheclassicalelas-ticitysolution,itisfoundthatnostresssingularityispresentatthecracktip,whichcanexplaintheproblemofmacroscopicandmicroscopicmechanics.

  • 标签: antiplane SHEAR wave the NON-LOCAL theory
  • 简介:Ameshlessradialbasisfunction(RBF)collocationmethodbasedontheEringennonlocalelasticitytheoryisdevelopedtocalculatethebandstructuresofternaryandquaternarynanoscalemulti-layeredphononiccrystals(PNCs)withfunctionallygraded(FG)interlayers.Detailedcalculationsareperformedforanti-planetransversewavespropagatinginsuchPNCs.TheinfluencesofFGandhomogeneousinterlayers,componentnumber,nonlocalinterfaceimperfectionsandnanoscalesizeoncut-offfrequencyandbandstructuresareinvestigatedindetail.Numericalresultsshowthatthesefactorshavesignificanteffectsonbandstructuresatthemacroscopicandmicroscopicscales.

  • 标签: 非局部弹性理论 径向基函数 能带结构 纳米尺寸 声子晶体 功能梯度