简介：Aconcurrentmultiscalemethodisdevelopedforsimulatingquasi-staticcrackpropagationinwhichthefailureprocessesoccurinonlyasmallportionofthestructure.Forthispurpose,amultiscalemodelisadoptedandbothscalesarediscretizedwithfinite-elementmeshes.Theextendedfiniteelementmethodisemployedtotakeintoaccountthepropagationofdiscontinuitiesonthefine-scalesubregions.Atthesametime,fortheothersubregions,thecoarse-scalemeshisemployedandisresolvedbyusingtheextendedmultiscalefiniteelementmethod.Severalrepresentativenumericalexamplesaregiventoverifythevalidityofthemethod.

简介：Inthispaper,adrivingstressfiniteelementmethodofelastic-plasticlargedeformationbasedonimplicittimeintegratingalgorithmandaneight-chainmolecularnetworkmodelisusedforthenumericalsimulationofthesimplesheartestofpolycarbonate(PC)materials.Thesimulatedresultsarecomparedwithexperimentalones.Thestrainlocalizationpropagationfortheshearbanddeforma-tionforsimplesheardeformationisinvestigatednumerieaUy.TheeffectsofmicrostructureparametersinthemodelonstrainsofteningandorientationhardeningofthePCarediscussedindetail.

简介：这份报纸在陶艺和脱臼包括阶段转变为无弹性的材料行为的纹理粗糙的原子论的模拟论述新方法论在金属的调停的粘性。方法论联合平衡方程和一个修改有限元素方法的原子论的明确的表达。与显著地自由的更少度比那些一个充分原子论的模型并且没有另外的组成的规则但是interatomic力量地，新纹理粗糙(CG)方法被显示在预言材料的非线性的组成的回答并且也复制象阶段转变那样的原子规模的现象可行(在硅和脱臼成核和移植，脱臼环的形成和在单个水晶的叠的差错带子的钻石-Sn)镍。指导在CG和现在的方法论在没有失去必要原子论的特征，当模特儿和无弹性的材料行为的模拟有效、有希望的相应完整的分子的动力学(MD)模拟表演之间的比较。潜在的应用和CG方法的限制也被讨论。

简介：Anon-localcontinuummodelforstrain-softeningsimplytakingplasticstrainordamagevari-ableasanon-localvariableisderivedbyusingtheadditivedecompositionprincipleoffinitedeformationgra-dient.Atthesametime,variationalequations,theirfiniteelementformulationsandnumericalconvolutedintegrationalgorithmofthemodelincurrentconfigurationusuallycalledco-movingcoordinatesystemaregiven.Stabilityandconvergenceofthemodelareprovenbymeansoftheweakconvergencetheoremofgen-eralfunctionandtheconvolutedintegrationtheory.Mathematicalandphysicalpropertiesofthecharacteris-ticsizeformaterialorstructureareaccountedforwithinthecontextofastatisticalweightedorkernelfunc-tion,andwayisinvestigated.Numericalsimulationshowsthatthismodelissuitablefortoanalyzingdefor-mationlocalizationproblems.

简介：Tsinghai-TibetPlateaubecomesanimportantresearchtopicofglobaltectonics,becauseofitsmarvelousthicknessandrapidupliftingsinceQuaternary.Byusingfiniteelementmethod,thenumericalsimulationiscarriedoutforthemovementofstructurallithosphere.Thedeformableelementsareemployedtosimulatestructuralzones,andthefrictionalmechanismisintroducedtoillustratethecharacteristicofazonewithacontactcracksurface.Theboundaryconditionsareprescribedbythedisplacementsaroundthepla-teau.Asaresult,thestressanddisplacementdistributionsareobtained,whichareconsistentwithPaxialorientationsoftheearthquakefocusmechanismandthemeasuredprincipalstressdirection.Analysisandes-timatearealsomadefortheevolutionofhistoricalprocessandpresentsituationoftheplateaulithosphere.

简介：ThenanostructuredAl-basedcompositespossessthecombinationofhighyieldstrengthandgoodductility.Inthispaper,amicromechanicalmodelispresentedtosimulatethemechanicalresponseofbimodalnanostructuredAlandtheparticle-reinforcedaluminummatrixcomposite(PAMC).Theconstitutiverelationsfordifferentphasesareaddressedinthemodel,aswellasthecontributionofmicrocracks.NumericalresultsshowthatthemodelcansuccessfullydescribetheenhancedstrengthandductilityofthebimodalnanostructuredAl,andthepredictionsofthePAMCareingoodagreementwiththeexperimentaldata.ItisworthnotingthatthestrengthandductilityaresensitivetothevolumefractionofconstituentsandthedistributionofmicrocracksinbothbimodalnanostructuredAlandPAMC.Therefore,thepresenttheoreticalresultscanbeusedtooptimizethemicrostructureforimprovingthemechanicalpropertiesofnanostructuredAl-basedcomposites.

简介：Basedonthecommercialcomputationalsoftware,athree-dimensionalfiniteelementmodeltosimulatethethermo-mechanicalbehaviorsinanuclearfuelrodisestablished;Bytakingintoconsiderationirradiation-swellingofthepelletandtheirradiationdamageeffectsinthecladdingtogetherwiththecouplingeffectsbetweenthetemperaturefieldandthemechanicalfield,theusersubroutinestodefinethespecialmaterialperformanceandboundaryconditionshavebeendevelopedindependentlyandvalidated.Three-dimensionalnumericalsimulationofthethermo-mechanicalcouplingbehaviorsinanuclearfuelrodiscarriedout,andtheevolutionrulesoftheimportantthermalandmechanicalvariablesareobtainedandanalyzed.Theresearchresultsindicatethat:(1)thefuelpelletswillbeincontactwiththecladdingathighburnup,whichwillinduceastrongmechanicalinteractionbetweenthem;(2)theirradiationcreepeffectplaysanimportantroleinthemechanicalbehaviorevolutioninthenuclearfuelrod.

简介：Theplasticanisotropyofsheetmetalisusuallycausedbypreferredorientationofgrains,developedbymechanicaldeformationandthermaltreatment.Inthepresentstudy,aTaylor-likepolycrystalmodelsuggestedbyAsaroandNeedlemanisappliedtoinvestigatetheevolutionoftheanisotropicbehaviorofafacecenteredcubic(FCC)polycrystallinemetal,whichithasundergoneaplane-straincompressionthatrationallysimulatesthecoldrollingprocessofFCCpolycrystallinepurealuminium.ByusingtheTaylor-likepolycrystalmodel,polefiguresareobtainedtodescribethetexturedevelopmentofpolycrystallineaggregateafterplane-straincompression,andthentheplasticanisotropyofpolycrystallineaggregateisevaluatedbystretchingthepolycrystallineaggregateindifferentdirectionintermofyieldstress.Accordingtotheresults,thecontoursoflongitudinalflowstressinthree-dimensionalorientationspacearegivenandanalyzed.ExperimentresultssimilartothepredictionofplanaranisotropycanbefoundintheliteraturewrittenbyTakahashietal.thatindirectlyshowthecorrectnessofthepredictionofnon-planarplasticanisotropybythisanalysis.

简介：Thispaperinvestigatestheequivalentmodelforthefrictionboundaryconditionbetweenblankandholderduringsheetmetalformingsimulation,andproposesanequivalentalgorithm,thethicknessthresholdvaluealgorithm,forthefirsttimebasedonthicknessweighting.Thisalgorithmassumesthattheholderclearanceisuniformduringsheetmetalforming;andthemainreasonfortheunevennessoffrictionforcedistributionundertheholderisthattheunevendeformationoftheblankleadstoitsuneventhicknessdistribution,whichmakesthelocalpressureontheblankdistributedunevenly.Thealgorithmproposedinthispapercaneffectivelysimulatetheinfluenceoftheunevennessontheformingprocess.Validityofthisalgorithmisverifiedbyacomparisonbetweenthesimulationresultsandtheexperimentalonesforthedrawingprocessofacarspringbase.

简介：基于三维(3D)分离元素方法(DEM)，在axisymmetric压缩和飞机下面的polydisperse范围的松开的集会上的undrained测试的礼品模拟结果拉紧的纸调节使用一个周期的房间。在现在的工作，undrained测试被在经常的体积条件下面使样品变形建模。undrained(有效)压力路径被显示是类似于在文学的试验性的结果的品质上。一个显微镜的参数以冗余性因素(RF)被用来识别液化的发作(或暂时的液化)，与等于定义转变从的统一的RF的条件对像液体的行为像固体。undrained行为被冗余性因素的进化在两undrainedaxisymmetric压缩和飞机紧张条件下面管理，这被发现，并且在为中等松开的系统的压力路径的deviatoric应力的颠倒由于系统成为结构的机制的事实发生(RF<1)短暂地在显微镜的水平在进化期间。

简介：Anumericalsimulationofstochasticdamaseevolutionprocessintheconditionoflowcyclefatigueloadingisdiscussed.Therelationsbetweendamagevariablesandmicro-cracksareob-tainedbymeansofthemicro-mechanicsmodeloftherepresentativevolumeelementproposedbyLemaitreandDufailiy.Thestochasticinitialdamagevaluesareintroducedinconsiderationoftheinherentmicro-defectsinmaterials.Themodelcombinedwithafiniteelementmethodisappliedtosimulatethedamageevolutionprocessunderlowcyclefatigueloading.Themicro-cracksonthesurfaceofaspecimenof19Mn6alloysteelaremeasuredwithareplicatechnique.Thenumericalresultsshowthatthenor.homogeneityofdamageandthelocalizationofthefatiguefailurearewellshownbytheproposedsimulations,andthefatiguelivesarereasonablypredicted.

简介：Basedonthetheoryofporousmedia,ageneralGurtinvariationalprinciplefortheinitialboundaryvalueproblemofdynamicalresponseoffluid-saturatedelasticporousmediaisdevelopedbyassuminginfinitesimaldeformationandincompressibleconstituentsofthesolidandfluidphase.Thefiniteelementformulationbasedonthisvariationalprincipleisalsoderived.Asthefunctionalofthevariationalprincipleisaspatialintegraloftheconvolutionformulation,thegeneralfiniteelementdiscretizationinspaceresultsinsymmetricaldifferential-integralequationsinthetimedomain.Insomesituations,thedifferential-integralequationscanbereducedtosym-metricaldifferentialequationsand,asanumericalexample,itisemployedtoanalyzethereflectionofone-dimensionallongitudinalwaveinafluid-saturatedporoussolid.Thenumericalresultscanprovidefurtherunderstandingofthewavepropagationinporousmedia.

简介：Plainconcreteisregardedasatwo-phasematerialcomprisingrandomlydistributedaggregatesandmortarmatrix.Aseriesofthree-pointbendingconcretebeamswithsymmetricorasymmetricdoublenotchesaremodeledusingthemodifiedrandomaggregategenerationandpackingalgorithm.Thecohesivezonemodelisusedasthefracturecriterionandthecohesiveelementsareinsertedintoboththemortarmatrixandtheaggregate-mortarinterfacesaspotentialmicro-crackingzones.Thedeadandalivecrackphenomenaarestudiedexperimentallyandnumerically;andtheinfluencesofnotchlocation,aggregatedistributionandgradationonfracturearenumericallyevaluated.Someimportantconclusionsaregiven.

简介：Multiscalesimulationsofthetiltedflat-endednanoindentationwithdifferenttiltedangles(from5?～30?)onthe(-110)surfaceofnickelcrystalwerestudiedusingtheQCmethod.Themodeloftheindentationisaflat-endindenterinclinedbyanangleεdrivenintoahalfplanevertically.Load-displacementresponses,initialstagesoftheplasticitydeformationsanddislocationemissionsfornickelfilmatdifferentinclinedangleswereobtainedandanalyzedaswell.Anenergycriterionwassuccessfullyproposedtoanalyzethecriticalloadforthefirstdislocationemissionbeneaththeedgeoftheindenter.Simulationresultsagreewellwithanalyticalones.AnelasticmodelbasedonthecontacttheoryandthePeierls-Nabarrodislocationmodelwerecombinedtoanalyzewhenandwherethedislocationwillbeemittedbeneaththelowersurfaceofaninclinedindenter.Resultsindicatethatthekeyparameteristheratioofthecontacthalfwidthtothepositionoftheslipplane.Thisparametershowstherangeinwhichadislocationwillprobablybeemitted.Thismechanismexplainsthesimulationresultswell.ThisworkisofvalueforunderstandingthemechanismofdislocationemissionsofFCCcrystalsundertiltedflatendednanoindentationwhileprovidingapproachestopredictingwhenthefirstdislocationwillbeemittedandwheresubsequentdislocationswillprobablybeemitted.

简介：Inthispaper,thefractureprocessofaunidirectionalCF/SiCsingleedge-notchedbeam(SENB)underthree-pointbending(TPB)isstudiedbymeansofmacro/micro-statisticalMonteCarlosimulation.Thesimulatedp-△curvesareinagreementwiththeexperimentalresultsbeforethepeaksofcurves,andthesimulatedmicroevolutionpatternsareinagreementwiththepatternsofthecracksurfaces,whichhaveverifiedthismethod.ItispreliminarilydemonstratedthatthesecondturningpointinthecompliancechangingratecurvecorrespondstothefractureinitiationforexperimentsonSENBunderTPBofunidirectionalCF/SiCcomposites.