简介：Accurateestimatesofductilitydemandsonbuckling-restrainedbracedframes(BRBFs)arecrucialtoperformance-baseddesignofBRBFs.AnanalyticalstudyontheseismicbehaviorofBRBFshasbeenconductedattheATLSSCenter,LehighUniversitytoprepareforanupcomingexperimentalprogram.TheanalysisprogramDRAIN-2DXwasusedtomodelaone-bay,four-storyprototypeBRBFincludingmaterialandgeometricnonlinearities.Thebucklingrestrainedbrace(BRB)modelincorporatesbothisotropicandkinematichardening.NonlinearstaticpushoverandtimehistoryanalyseswereperformedontheprototypeBRBF.PerformanceobjectivesfortheBRBsweredefinedanduscdtoevaluatethctime-historyanalysisresults.ParticularemphasiswasplacedonglobalductilitydemandsandductilitydemandsoatheBRBs.Thesedemandswerecomparedwithanticipatedductilitycapacities.Theanalysisresults,alongwithresultsfromsimilarpreviousstudics,areusedtoevaluatetheBRBFdesignprovisionsthathavebeenrecommendedforcodificationintheUnitedStates.ThcresultsshowthatBRBmaximumductilitydemandscanbeashighas20to25.ThesedemandssignificantlyexceedthoseanticipatedbytheBRBFrecommendedprovisions.Resultsfromthestaticpushoverandtimehistoryanalysesareusedtodemonstratewhytheductilitydemandsexceedthoseanticipatedbytherecommendedprovisions.TheBRBqualificationtestingprotocolcontainedintheBRBFrecommendedprovisionsisshowntobeinadequatebecauseitrequiresonlyamaximumductilitydemandofatmost7.5.Modificationstothetestingprotocolarerecommended.

简介：Thispaperattemptstoinvestigatethebucklingandpost-bucklingbehaviorsofpiezoelectricnanoplatebasedonthenonlocalMindlinplatemodelandvonKarmangeometricnonlinearity.Anexternalelectricvoltageandauniformtemperatureriseareappliedonthepiezoelectricnanoplate.Boththeuniaxialandbiaxialmechanicalcompressionforceswillbeconsideredinthebucklingandpost-bucklinganalysis.Bysubstitutingtheenergyfunctionsintotheequationoftheminimumtotalpotentialenergyprinciple,thegoverningequationsarederiveddirectly,andthendiscretizedthroughthedifferentialquadrature(DQ)method.Thebucklingandpost-bucklingresponsesofpiezoelectricnanoplatesarecalculatedbyemployingadirectiterativemethodunderdifferentboundaryconditions.Thenumericalresultsarepresentedtoshowtheinfluencesofdifferentfactorsincludingthenonlocalparameter,electricvoltage,andtemperatureriseonthebucklingandpost-bucklingresponses.

简介：Thedynamictorsionalbucklingandpost-bucklingofelasto-plasticcircularcylindricalshellisstudied.BytheusageoftheBodner-Partomconstitutiverelation,thepresentvisco-plasticproblemistreat-edasanorthotropicelasticproblem.Basedonthenonlinearlargedeflectionshelltherory,thegoverningdynamicbucklingequationissolvedbytheRunge-Kuttamethod,andthecriticalbucklingstressisdeter-minedbytheB-Rcriterion.Thepresentpaperismainlyfocusedontheimperfectionsensitivity,thestrainratesensitivity,andthedynamicpost-bucklingcharactersfortheshellloadeddynamicallywithaconstantshearstrainrate.Numericalresultsshowthatthecriticalshearstressandimperfectionsensitivitywillin-creasewiththeincreaseofstrainrate.Itisfoundthattheelasticbucklingstressismoresensitivetoimperfectionthanthevisco-plasticbuckling.Thepresentresearchalsorevealssomedynamicpost-bucklingcharactersforthecylindricalshell,anditisshownthattheshellwillvibra

简介：Onthebasisofboththegeneraltheory[1,2]andthefiniteelementmethod[4]ofperforatedthinplateswithlargedeflection,thebucklingandpost-bucklingofannularplatesundernon-axisymmetricplaneedgeforcesarestudied.

简介：AmethodoflocalizationisproposedtolowerthehighorderofequationsinFEMcalcula-tionforthestabilityofacomplexthin-walledstructure.Thelocalizedanalysisenablesustoobtainboththeupperandlowerlimitsforthebifurcatingpointinawholelinearelasticstructuralsystem,aswellasanap-proximatesolutiontoasymptoticpost-bucklingproblem.Somenumericalexamplesareincluded.

简介：一个一阶的扭转理论基于Vlasov理论被开发了调查开的薄墙的横梁的制止的扭转。生气的节的全部的旋转被划分成免费变弯旋转并且一制止砍旋转。在一阶的扭转理论，圣韦南特转矩仅仅与免费变弯旋转有关，圣韦南特转矩的表示被使用一个半逆方法导出。在变弯的转矩之间的关系并且制止砍旋转被使用一个精力方法建立。扭转砍系数然后被获得。根据扭转平衡，管理制止的扭转的微分方程被导出，相应起始的方法被给解决方程。在全部的旋转和免费变弯旋转之间的关系被获得。一个参数，与生气的节和横梁长度的僵硬性质被联系，被介绍决定条件，圣韦南特常数在下面是可以忽略的。因而，一个简化理论被导出。数字例子被说明验证当前的途径，当前的理论的结果与一些另外的可得到的方法的那些相比。比较的结果证明当前的理论提供更精确的结果。在一根塑造隧道的伸臂横梁的例子，简化理论的适用性被参数学习决定。

简介：Thebucklingofthingelfilmhasattractedmuchattentionduetoitsapplicationsinthedesignofthreedimensionalstructurefromtwo-dimensionaltemplate.Wehaveestablishedananalyticalmodeltostudytheswelling-inducedbucklingofathingelstripwithoneedgeclampecdandtheothersfree.Theclosed-formsolutionsfortheamplitudeandwavelengthofthebuckledshapeareobtainedbyenergyminimizationofthetotalpotentialenergy.Theanalyticalresultsagreewellwithfiniteelementanalysisbasedontheinhomogeneousgeltheorywithoutanyparameterfitting.Themodelprovidesaroutetostudycomplexpostbucklingbehaviorsofthingelfilmsandguidelinestodesignthebuckledconfigurationquantitativelybycontrollingtheswellingratio.

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简介：Themostsignificantdifferencesbetweencontinuousweldedrails(CWRs)andgeneralsplit-typeconnectorsareaxialcompressioninthelongitudinaldirection,bucklingstabilityandotherissuesgeneratedundertheinfluenceofthermaleffect.Underthermaleffect,adynamicalbehaviorsimilartothatofabeamfixedontwosidesoccursinthecentrallockedareaoftheweldedrail,asthereisaxialcompressionbutnopossibilityofsliding.Continuousweldedrailsdonotcontractorexpand,andaresupportedbythedynamicalsystemmadeupofballastsandrailclips.Therail-supportsystemmentionedabovehasthefeaturesofnon-uniformmaterialdistributionanduncertaintyofconstructionquality.Duetothesefacts,thedynamicsmethodbasedonthelinearelastichypothesiscannotcorrectlyevaluatetherail'sbucklingconditions.ThisstudyisaimedatapplyingFiniteDifferenceMethod(FDM)andMonteCarloRandomNormalVariablesMethodtotheanalysisofweldedrail'sbucklingbehaviorduringthetrain'saccelerationanddeceleration,underthermaleffectanduncertainfactorsofballastandrailclips.Theanalysisresultshowedthatbucklingoccursunderthecombinedeffectofthermaleffectandthetrain'sdecelerationforceco-effectandthevarianceratioofballastandrailclipsisover0.85,orunderthecombinedeffectofthermaleffectandthetrain'saccelerationforcewhenthevarianceratioisover0.88.

简介：-Thispaperadoptsapproximateformulasforresidualstressescausedbycoldbendingforplateswithstress-straincurveforma=Kn.Atypicaldistributionofthelongitudinalresidualstressduetoweldingisalsoassumed.Theeffectsofresidualstressduetocoldbendingandweldingonplasticbucklingofaxiallycompressedcylindricalshellsarestudiedbythefiniteelementmethod.

简介：用机能上地分级的材料(FGM)做的圆柱的壳的热弄弯行为被学习。材料成分由组成陶器并且金属。越过壳厚度的材料性质被假定以混合物的体积部分规则根据简单幂定律分布被分级。基于Donnell壳理论，以排水量部件弄弯的无尺寸的部分微分方程的一个系统被导出。变量的分离的方法被用来转变管理方程到平常的微分方程(颂诗)。一个射击方法被用来在边界条件的二种类型下面寻找微分方程的数字答案。幂定律索引，无尺寸的几何参数，和批评弄弯温度上的温度比率的效果详细被讨论。

简介：Electronicsystemswithlargestretchabilityhavemanyapplications.Apreciselycontrolledbucklingstrategytoincreasethestretchabilityhasbeendemonstratedbycombininglithographicallypatternedsurfacebondingchemistryandabucklingprocess.Thebuckledgeometrywasassumedtohaveasinusoidalform,whichmayresultinerrorstodeterminethestrainsinthefilm.Atheoreticalmodelispresentedinthislettertostudythemechanicsofthistypeofthinfilm/substratesystembydiscardingtheass...

简介：Incontinuousannealinglines/hotgalvanizing,stripsareguidedbyupperandlowerrollsinanalternateupanddownverticalmotion.Thiskindofprocessconsistingofheating,soaking,andcoolingfurnaces（orzones）hasseveraladvantagesintermsofproductivityandproductquality.Mainproblemsencounteredincontinuousannealinglinesaremisguidingandformationofbuckling.Thestripbucklingcausesthestriptoberejectedand,intheworstcase,thestripbreaksandthecontinuousannealinglinesarecompelledtostop.Inthispapertheelastic-plasticmodelofthestriptravelingandthecorrespondingboundaryconditionwereconstructeddependantonthetheoryofmechanic.Simulationsareperformedintwosteps.First,ahomogeneouslongitudinaltensilestressisappliedatoneendofthestrip,theotherendofthestripandtherollarerestricted.Inthesecondstep,theappliedtensionremainsconstant.Auniformdisplacementisappliedtotheotherendofthestripandarotationtotheroll.Thetransversecompressivestress,thebucklingformationduringstriptravelingprocess,thelocationforthebucklingtakingplaceandthebucklingcriterionwereinvestigatedsystematically.Theresultshowsthatthetransversecompressivestressincreaseswiththeincreaseofthetensilestressandthecrownofthetaperedroll.Becausethecontactareabetweenthetaperedrollandthestripincreasewiththedecreaseofthecrown,thetensilestressdistributionismorehomogeneousinthetransversedirectionofthestrip.Anadditionaltransversecompressivestressiscreatedandabucklingisalsoobservedduetothefrictionduringthestripmotioninthesecondstep.Oncethebucklingisappearance,itisveryhardtoberemovedonlythroughdecreasingtheappliedlongitudinaltension,becausethestripwrinklestillkeepshighlevelduetotheeffectofthebuckledstrip,thewrinklewouldevolveintobucklingeventually.Thebucklingformationprocesspredictedbythefiniteelementmodelisverysimilartothose

简介：ＩｎｔｒｏｄｕｃｔｉｏｎＩｍｐｏｒｔａｎｔａｐｌｉｃａｔｉｏｎｓｏｆｔｈｅｓｔａｂｉｌｉｔｙａｎａｌｙｓｉｓｏｆｓｈｅｌｓｃａｎｂｅｆｏｕｎｄｉｎｔｈｅｍｏｄｅｒｎｅｎｇｉｎｅｒｉｎｇｒａｎｇｉｎｇｏｖｅｒｔｈｅａｅｒｏｓｐａｃｅ，ｍａｒｉｎｅ，ａｒ...

简介：Theimpactbucklingofalaminatedcompositebarisinvestigatedincaseofoneofitsendsmovingduetoaxialimpactcompression.Thegoverningequationsconsideringthefirst-ordersheardeformationeffectarederivedbytheHamiltonprincipleandsolvedbythefinitedifferencemethod.ThecriticalaxialshortnessisdeterminedbytheB-Rcirterion.Thegivenexampleisusedtohighlightthein-fluencesofinitialimperfection,impactvelocity,stresswaveandcoupledstiffness.Itisfoundthattheunsymmetricallylaminatedbarhasaquitedifferentdynamicbucklingbehaviourfromthatofthesymmetricallylaminatedbar.

简介：Westudythebucklingofaonefibercompositewhosematrixstifnessisslightlydependentonthecompressiveforce.Weshowthattheequilibriumcurvesofthesystemexhibitalimitloadwhentheinducedstifnessparametergetsbiggerthanathreshold.Thislimitloadincreaseswhenthestifnessparameterisincreasinganditisrelatedtoapossiblelocalizedpathinthepost-bucklingdomain.Suchachangeinthemaximumloadmaybeverydesirablefromastructuralstandpoint.

简介：我们在场微分照(DQ)的申请为有指数地基于Euler-Bernoulli，Timoshenko，瑞迪，和Levison的四个不同横梁理论改变僵硬的nanobeams的弄弯的分析的方法。明确的表达基于Eringen的非局部的弹性理论。新结果被介绍为指导了并且简单地支持了指导边界条件。数字结果被获得在批评弄弯负担参数上调查非局部的参数，length-to-height比率，边界条件，和不一致的参数的效果。当批评弄弯负担参数随length-to-height比率的增加增加时，批评弄弯负担随非局部的参数的增加减少，这被观察当批评弄弯负担参数随length-to-height比率的增加增加时。

简介：Afiniteelementasymptoticanalysisfordeterminingthelowerbounddynamicbucklingestimatesofimperfection-sensitivestructuresundersteploadofinfinitedurationispresented.Thelowerbounddynamicbucklingloadsandthecorrespondingdisplacementsaresoughtintheformofasymptoticexpansionsbasedonthestaticstabilitycriterionandtheycanbedeterminedbysolvingnumerically(FEM)severallinearproblemswithasinglenonsingularsub-stiffnessmatrix.

简介：Thecentralpostisoneofthecriticalcomponentsforthelowaspectratiotokamak,whichenduresnotonlyatremendousohmicheatingbecauseitcarriesaratherhighcurrent,butalsoalargeneutronheatingandirradiationowingtotheplasmaoperation.TheDScopperalloyGlidcopAL-25[8]waschosenastheconductormaterialforitsadequatemechanicalpropertiesandphysicsproperties.Thecentralposthasacylindricalstructurewithlotsofcoolingchannels.Thelengthofthecentralpostforthenextgenerationofnuclearfusionsphericaltokamakswillbemorethan10mor20m.Thestructuralstabilityisverycrucial.Whentheappliedloadislargerthanthestructurecriticalbucklingload,thedevicewillloseitsstabilityandcollapse.Inordertocal'culatethecriticalbucklingload,a1/6-segmentfiniteelementmodelwasusedandtheforceactingonthecentralpostwassimulated.Theresultsshowedthattheverticalcompressivestressesmainlyaffectthestabilityofthecentralpost.Thelinearbucklinganalysisresultswithfiniteelementmethodbasedonsmalldeformationtheoryweregiveninthispaper.Therelationcurvesandfunctionsforbucklingfactor,dependingonthedifferentlengthsandtheradiusofthecentralpost,thediameterofcoolingchannelandthemaximumallowablecurrentdensity,werealsoshown.

简介：模式跳是在buckling以后区域的不稳定性现象，它在平衡配置引起一个突然的变化并且因此是有害的组织。一个部分有弹性的基础的配置能直接导致模式从弄弯的阶段并且通过整个buckling以后区域联合。在模式跳上由于部分基础的配置联合效果的模式被调查并且示威了是决定模式跳的一个重要因素。由适当地选部分有弹性的基础为配置，模式跳能被避免。