简介:Thenon-probabilisticreliabilityinhigherdimensionalsituationscannotbecalculatedefficientlyusingtraditionalmethods,whicheitherrequirealargeamountofcalculationorcausesignificanterror.Inthisstudy,anefficientcomputationalmethodisproposedforthecalculationofnon-probabilisticreliabilitybasedonthevolumeratiotheory,specificallyforlinearstructuralsystems.Thecommonexpressionfornon-probabilisticreliabilityisobtainedthroughformuladerivationwiththeamountofcomputationconsiderablyreduced.Thecompatibilitybetweennon-probabilisticandprobabilisticsafetymeasuresisdemonstratedthroughtheMonteCarlosimulation.Thehighefficiencyofthepresentedmethodisverifiedbyseveralnumericalexamples.
简介:Anon-localcontinuummodelforstrain-softeningsimplytakingplasticstrainordamagevari-ableasanon-localvariableisderivedbyusingtheadditivedecompositionprincipleoffinitedeformationgra-dient.Atthesametime,variationalequations,theirfiniteelementformulationsandnumericalconvolutedintegrationalgorithmofthemodelincurrentconfigurationusuallycalledco-movingcoordinatesystemaregiven.Stabilityandconvergenceofthemodelareprovenbymeansoftheweakconvergencetheoremofgen-eralfunctionandtheconvolutedintegrationtheory.Mathematicalandphysicalpropertiesofthecharacteris-ticsizeformaterialorstructureareaccountedforwithinthecontextofastatisticalweightedorkernelfunc-tion,andwayisinvestigated.Numericalsimulationshowsthatthismodelissuitablefortoanalyzingdefor-mationlocalizationproblems.
简介:Thefreenon-linearvibrationofaxiallymoving,elastic,andtensionedbeamsonfixedsupportsisinvestigatedinthispaper.Twotypesofnon-linearity,namely,thedifferentialtypeandintegro-differentialtype,areanalyzed.Approximatesolutionsaresoughtusingthemethodofmultiplescales.Thecontributionofnon-linearitytotheresponseincreaseswiththeaxialspeed,andgrowsmostrapidlynearthecriticalspeed.Ithasbeenfoundthatthedifferentialtypenonlinearityisstrongerthantheintegro-differentialtypenon-linearitybyanalyzingthenon-lineareffectsonnaturalfrequencies.
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。
简介:Theplasticanisotropyofsheetmetalisusuallycausedbypreferredorientationofgrains,developedbymechanicaldeformationandthermaltreatment.Inthepresentstudy,aTaylor-likepolycrystalmodelsuggestedbyAsaroandNeedlemanisappliedtoinvestigatetheevolutionoftheanisotropicbehaviorofafacecenteredcubic(FCC)polycrystallinemetal,whichithasundergoneaplane-straincompressionthatrationallysimulatesthecoldrollingprocessofFCCpolycrystallinepurealuminium.ByusingtheTaylor-likepolycrystalmodel,polefiguresareobtainedtodescribethetexturedevelopmentofpolycrystallineaggregateafterplane-straincompression,andthentheplasticanisotropyofpolycrystallineaggregateisevaluatedbystretchingthepolycrystallineaggregateindifferentdirectionintermofyieldstress.Accordingtotheresults,thecontoursoflongitudinalflowstressinthree-dimensionalorientationspacearegivenandanalyzed.ExperimentresultssimilartothepredictionofplanaranisotropycanbefoundintheliteraturewrittenbyTakahashietal.thatindirectlyshowthecorrectnessofthepredictionofnon-planarplasticanisotropybythisanalysis.
简介:Theproblemconsideredhereistheresponseofanon-homogeneouscompositematerialcontainingsomecrackssubjectedtodynamicloading.Itisassumedthatthecompositematerialisor-thotropicandallthematerialpropertiesdependonlyonthecoordinatey(alongthethicknessdirection).Intheanalysis,theelasticregionisdividedintoanumberofpliesofinfinitelength.Thematerialpropertiesaretakentobeconstantsforeachply.ByutilizingtheLaplacetransformandFouriertransformtechnique,thegeneralsolutionsforpliesarederived.Thesingularintegralequa-tionsoftheentireelasticregionareobtainedandsolvedbythevirtualdisplacementprinciple.Attentionisfocusedonthetime-dependentfullfieldsolutionsofstressintensityfactor(SIF)andstrainenergyreleaserate.Asanumericalillustration,thedynamicstressintensityfactorofasubstrate\functionallygradedfilmstructurewithtwocracksundersuddenlyappliedforcesoncracksfacearepresentedforvariousmaterialnon-homogeneityparameters.
简介:ThehigherorderasymptoticfieldsatthetipofasharpV-notchinapower-hardeningmaterialforplanestrainproblemofModeⅠarederived.Theorderhierarchyinpowersofrforvarioushardeningexponentsnandnotchanglesβisobtained.Theangulardistributionsofstressforseveralcasesareplotted.Theself-similaritybehaviorbetweenthehigherordertermsisnoticed.ItisfoundthatthetermswithhigherordercanbenegleetedfortheV-notchangleβ>45°.
简介:Anewcomputationschemeproposedtotacklecommensurateproblemsisdevelopedbymodifyingthesemi-analyticapproachforminimizingcomputationalcomplexity.Usingtheproposedscheme,thelimitstateequations,usuallyreferredtoasthefailuresurface,areobtainedfromtransformationofanintervalvariabletoanormalizedone.Inordertominimizethecomputationalcost,twoalgorithmsforoptimizingthecalculationstepshavebeenproposed.Themonotonicityoftheobjectivefunctioncanbedeterminedfromnarrowingthescopeofintervalvariablesinnormalizedinfinitespacebyincorporatingthealgorithmsintothecomputationalscheme.Twoexamplesareusedtoillustratetheoperationandcomputationalefficiencyoftheapproach.Theresultsoftheseexamplesshowthattheproposedalgorithmscangreatlyreducethecomputationcomplexitywithoutsacrificingthecomputationalaccuracy.Theadvantageoftheproposedschemecanbeevenmoreefficientforanalyzingsophisticstructures.
简介:Basedontheporousmediatheoryandbytakingintoaccounttheeffectsoftheporefluidviscidity,energyexchangesduetotheadditionalthermalconductionandconvectionbetweensolidandfluidphases,amathematicalmodelforthedynamic-thermo-hydro-mechanicalcouplingofanon-localthermalequilibriumfluid-saturatedporousmedium,inwhichthetwoconstituentsareassumedtobeincompressibleandimmiscible,isestablishedundertheassumptionofsmalldeformationofthesolidphase,smallvelocityofthefluidphaseandsmalltemperaturechangesofthetwoconstituents.Themathematicalmodelofalocalthermalequilibriumfluid-saturatedporousmediumcanbeobtaineddirectlyfromtheaboveone.SeveralGurtin-typevariationalprinciples,especiallyHu-Washizutypevariationalprinciples,fortheinitialboundaryvalueproblemsofdynamicandquasi-staticresponsesarepresented.Itshouldbepointedoutthatthesevariationalprinciplescanbedegeneratedeasilyintothecaseofisothermalincompressiblefluid-saturatedelasticporousmedia,whichhavebeendiscussedpreviously.
简介:Anintegratedcouplingelementconsideringwheel-railinterfaceforanalyzingthedynamicresponsesofvehicle-rail-bridgeinteractionsystemwithanon-uniformcontinuousbridgeispresented.Thegoverningequationsoftheinteractionsystemareestablishedfirst,andthesolutionprocedureandassemblymethodofthecouplingelementaredemonstrated.Finally,theaccuracy,efficiencyandfunctionoftheintegratedcouplingelementaretestedusingtwonumericalexamples.Theinfluencesofdifferentcombinationsofrailandbridgeelementlengthinthecouplingelementonthesolutionareinvestigated,andtheeffectsofdifferentrailirregularitiesonthedynamicresponsesarediscussed.
简介:Inthispaper,thescatteringofharmonicantiplaneshearwavesbytwofinitecracksisstudiedusingthenon-localtheory.TheFouriertransformisappliedandamixedboundaryvalueprob-lemisformulated.Thenasetoftripleintegralequationsissolvedusinganewmethod,namelySchmidt’smethod,ThismethodismoreexactandmorereasonablethanEringen’sforsolvingthiskindofproblem.Theresultofthestressnearthecracktipwasobtained.Contrarytotheclassicalelas-ticitysolution,itisfoundthatnostresssingularityispresentatthecracktip,whichcanexplaintheproblemofmacroscopicandmicroscopicmechanics.
简介:Basedontheextendedhomogeneouscapacityhighprecisionintegrationmethodandthespectrummethodofvirtualboundarywithacomplexradiusvector,anovelsemi-analyticalmethod,whichhassatisfactorycomputationeffectivenessandprecision,ispresentedforsolvingtheacousticradiationfromasubmergedinfinitenon-circularcylindricalshellstiffenedbylongitudinalribsbymeansoftheFourierintegraltransformationandstationaryphasemethod.Inthiswork,besidesthenormalinteractingforce,whichiscommonlyadoptedbysomeresearchers,theotherinteractingforcesandmomentsbetweenthelongitudinalribsandthenon-circularcylindricalshellareconsideredatthesametime.Theeffectsofthenumberandthesizeofthecross-sectionoflongitudinalribsonthecharacteristicsofacousticradiationareinvestigated.NumericalresultsshowthatthemethodproposedismoreefficientthantheexistingmixedFE-BEmethod.