简介：Finiteelementmethod(FEM)hasbeenusedtoanalyzethestressandstrainfieldsandthestresstri-axiallevelsaroundthetipofthecrackundermode-Ⅱloading.Theresultsshowthat:undermode-Ⅱloading,thedirectionofthemaximumtensilestressandthatofthemaximumtri-axiallevels(R_)existatanangleof-75.3°fromtheoriginalcrackplane:themaximumshearstressandR_=0existalongtheoriginalcrackplane.Mode-ⅡloadingexperimentusingBHW-35steelatdifferenttemperaturesshowthattherearetwokindsoffracturemode.openingmode(ortensilemode)andslidingmode(orshearmode).Ade-creaseintemperaturecausesthefracturemodetochangefromshearmodetotensilemode.ForBHW-35steel,thiscriticaltemperatureisabout-90C.Actually.underanykindofloadingmode(modeⅠ,modeⅡ,modeⅢormixedmode),therealwaysexistseveralkindsofpotenitalfracturemodes(forexample,openingmode.slidingmode.tearingmodeormixedmode).Theeffectoftemperatureundermode-Ⅱloadingisactuallyrelatedtothechangeoftheelastic-plasticpropertiesofthematerial.

简介：Solutionstoapiezoelectrichalf-planewithafixedconductorsurfaceelectrodesubjectedtotwogeneralizedsingularities(linedislocationand/orlineforceandfreecharge)arepresented.Coulombforcesactingonthesingularitiesduetotheboundarypolarizationchargesofmediumandtheinductioncharg-esofconductorelectrodeareanalyzedindetail.Theinteractionbetweenthetwosingularitiesisalsoanalyzednumerically.ResultsshowthatCoulombforceswillbecomeimportantasthefreechargeapproachestheboundaryortwosingularitiesmoveclosely.

简介：PhaseShiftingAndLogicalMoire(PSALM)isakindofcomputerimageprocessingmethodwhichcanbeusedinphasemeasurementandtoobtaintheshape,deformationandstraindistributionofanobject.Thispaperpresentsthestructureandworkingprocedureofa2DphasemeasurementPSALM2Dprogramanditsapplication.Whenanalyzingmoireinterferometricfringes,wecanobtain2Ddistributionofdisplacementandstrain.Whenitisusedinreflectionmoirewecanmeasuretheslopeofaspecimen.SatisfactoryvisualizationandquantitativeresultsaregivenbyPSALM2D.

简介：Theboundaryelementmethodisusedforthemodalanalysisoffreevibrationof2-Dcompositestructuresinthispaper.Sincetheparticularsolutionmethodisusedtotreatthetermsofbodyforces(inertialforces)intheequationofmotion,onlystaticfundamentalsolutionsareneededinsolvingtheproblem.Foranisotropiccantileverbeam,thenumericalresultsobtainedbyusingtheBEMpresentedinthispaperareingoodagreement,withthoseofusingFEMorotherBEM,butthisBEMcanalsobeusedtoanalyzeproblemsforanisotropicmaterials.Forsimplysupportedcompositelaminatedbeams,thecomparisonsofthenumericalresultsobtainedbythismethodwiththeanalyticalresultsobtainedby1-Dlaminatedbeamtheoryindicatethatiftheratiooflength/thicknessisgreaterthan20,theresultsofthetwomethodsareingoodagreement,butiftheratiooflength/thicknessislessthan20,bigerrorswilloccurfor1-Dlaminatedbeamtheory.

简介：在这篇论文，为orthotropic板的飞机裂缝问题的压力紧张因素的评估相等参数用一个分数维的二水平的有限元素方法(F2LFEM)被调查。一个orthotropic裂缝问题的一般答案被与各向同性的裂缝问题吸收这个问题获得，并且在F2LFEM作为全球插值功能被采用。在裂缝板的裂缝尖端的邻居，分数维的几何学概念被介绍完成有类似比率的类似的网孔不到一个并且产生一个无穷小的网孔以便在二邻近的层的僵硬矩阵之间的关系是相等的。在裂缝尖端附近的自由的很多度被转变到概括坐标的一个小集合。数字例子证明这个方法在评估压力紧张因素(SIF)有效、精确。

简介：尽管边界排水量和拖拉是处于在一个非退化的边界点的一个弹性问题的边界条件的独立的地变量，在那里存在在在一条单个边界的边界排水量衍生物和拖拉之间的奇特紧张的明确的关系指。在为2D的一个单个光滑的点的关系的分析表格各向同性的有弹性的问题在这个工作被建立了。由使用关系，单个边界点的位置和未知边界的相应奇特紧张回答变量能被决定priori。因此，未知边界的更适当的形状函数在单个元素回答变量能被构造。一个数字例子证明用发达理论的BEM分析的精确性极大地被增加。

简介：Thenonlinearbehaviorofacantileveredfluidconveyingpipesubjectedtoprincipalparametricandinternalresonancesisinvestigatedinthispaper.Theflowvelocityisdividedintoconstantandsinusoidaiparts.Thevelocityvalueoftheconstantpartissoadjustedsuchthatthesystemexhibits3:1internalresonancesforthefirsttwomodes.Themethodofmultiplescalesisemployedtoobtaintheresponseofthesystemandasetoffourfirst-ordernonlinearordinary-differentialequationsforgoverningtheamplitudeoftheresponse.TheeigenvaluesoftheJacobianmatrixareusedtoassessthestabilityoftheequilibriumsolutionswithvaryingparameters.Thecodimension2derivedfromthedouble-zeroeigenvaiuesisanalyzedindetail.Theresultsshowthattheresponseamplitudemayundergosaddle-node,pitchfork,Hopf,homoclinicloopandperiod-doublingbifurcationsdependingonthefrequencyandamplitudeofthesinusoidalflow.Whenthefrequencyofthesinusoidalflowequalsexactlyhalfofthefirst-modefrequency,thesystemhasaroutetochaosbyperiod-doublingbifurcationandthenreturnstoaperiodicmotionastheamplitudeofthesinusoidalflowincreases.

简介：Toconsidertheanisotropicdamageinfatigue,animprovedboom-panelmodelispresentedtosimulatearepresentativevolumeelement(RVE)intheframeworkofcontinuumdamagemechanics.TheanisotropicdamagestateoftheRVEisdescribedbythecontinuityextentsofboomsandpanels,whosedamageevolutionsareassumedtobeisotropic.Thenumericalimplementationisproposedonthebasisofdamagemechanicsandthefiniteelementmethod.Finally,theapproachisappliedtothefatiguelifepredictionof2A12-T4aluminiumalloyspecimenundercyclicloadingoftension-torsion.Theresultsindicateagoodagreementwiththeexperimentaldata.