ANSYS工程分析

Chapter4ANSYS結構分析的基本觀念BasicConceptsforANSYSStructuralAnalysis2Contents4.1學科領域與元素類別DisciplinesandElementTypes4.2分析類別AnalysisTypes4.3線性分析與非線性分析LinearAnalysisandNonlinearAnalysis4.4材料模式MaterialModels4.5材料的破壞準則FailureCriteriaofMaterials4.6實例:動態分析Example:DynamicAnalysis4.7實例:非線性分析Example:NonlinearAnalysis4.8練習題:幾何非線性Exercise:GeometricNonlinearity3第4.1節學科領域與元素類別DisciplinesandElementTypes44.1.1學科領域•結構分析StructuralAnalysis•熱傳分析ThermalAnalysis•流場分析FluidDynamicAnalysis•電場分析ElectricFieldAnalysis•磁場分析MagneticFieldAnalysis•耦合場分析Coupled-fieldAnalysis54.1.2耦合場分析•Example1:ThermalStressAnalysis•Example2:Structure-FluidInteractions•Example3:ThermalActuator64.1.3元素類別ElementTypes•ANSYSelementsareclassifiedaccordingto–Discipline–Dimensionality–Geometry–Order•Example–SOLID45:3Dhexahedrallinearstructuralelement–PLANE67:2Dquadralaterallinearcoupledthermal-electricelement7第4.2節分析類別AnalysisTypes84.2.1分析類別AnalysisTypes•StaticAnalysis•DynamicAnalysis–TransientAnalysis–ModalAnalysis–HarmonicResponseAnalysis–etc.•BucklingAnalysis•StructuralAnalysis–Static,Transient,Modal,Harmonic,Buckling,etc.•ThermalAnalysis–Steady-state,Transient•ElectricFieldAnalysis–Static,Transient,Modal,Harmonic•etc.94.2.2暫態分析TransientAnalysis•Inertiaforces•Dampingforces•Elasticforces•ExternalforcesFKDDCDM104.2.3靜態分析StaticAnalysis•Whendynamiceffectscanbeneglected,aproblemcanbesolvedstatically.•Dynamiceffectscanbeneglectedonlywhenthedeformationvelocityandaccelerationaresmall.•Twocases:–Steady-statesolution–approximationsolutionforareal-worldproblem.FKD114.2.4模態分析ModalAnalysis•Modalanalysisistoanalysisastructureunderfreevibration.•Thesolutionstypicallyinclude–Vibrationfrequencies(orperiods)–Vibrationmodes0KDDCDM124.2.5諧和反應分析HarmonicResponseAnalysis•Harmonicresponseanalysisistoanalysisastructureunderperiodicexcitationofexternalforces.•Thesolutionstypicallyincludemaximumresponsesundervariousfrequenciesofexternalforces13第4.3節線性分析與非線性分析LinearAnalysisandNonlinearAnalysis144.3.1線性分析LinearAnalysis•Smalldeformation•Hooke’slawappies•Nostatusortopologicalchanges,eg.,contactsLoadsResponses154.3.2非線性分析NonlinearAnalysis•Geometricnonlinearity•Materialnonlinearity•Statusnonlineaity16第4.4節材料模式MaterialModels174.4.1材料模式MaterialModels•Materialmodelsaremathematicallyrepresentedbyasetofequationscalledconstitutiveequations.•Theconstitutiveequationsdescribetherelationsbetweenstressesandstrains(orstrainrates).•Theparametersintheconstitutiveequationsarecalledmaterialparameters.•ANSYSprovidesmanymaterialmodelstobechosenfrom.184.4.2彈性與塑性(1/2)Elasticvs.PlasticElasticmaterials(a)Nonlinearelastic(b)Hysteresiselastic(c)LinearElasticStressStrain(a)StressStrain(b)(c)StressStrain194.4.2彈性與塑性(2/2)Elasticvs.PlasticPlasticmaterialsStrainStress204.4.3黏滯性與非黏滯性(1/3)Viscousvs.NonviscousNonvisousmaterialsTimeStressTimeStrain214.4.3黏滯性與非黏滯性(2/3)Viscousvs.NonviscousVisousmaterialsStressStrainTimeTime224.4.3黏滯性與非黏滯性(3/3)Viscousvs.NonviscousCreepingTimeStressTimeStrainTimeStrainTimeStressStressRelaxation234.4.4均質性與非均質性材料Homogeneousvs.Heterogeneous•Amaterialbodyissaidtobehomogeneousifithasuniformmaterialpropertieseverywhereinthebody.•Otherwiseitissaidtobeheterogeneous.•Notethat,homogeneousnessdoesnotnecessarilyimplyisotropy.244.4.5等向性、非等向性、與正交性材料(1/2)Isotropic,Anisotropic,andOthothropicMaterials•Amaterialissaidtobeisotropicifithasthesamematerialpropertiesalonganydirectionsinthebody.•Otherwiseitissaidtobeanisotropic.•Ananisotropicmaterialissaidtobeorthotropic,iftheplanesofmaterialsymmetryaremutuallyorthogonal.254.4.5等向性、非等向性、與正交性材料(2/2)Isotropic,Anisotropic,andOthothropicMaterialsGGGEEEEEEEEEzxzxyzyzxyxyzyxzzyxyzyxxDσεzxzxzxyzyzyzxyxyxyyyzyxxzxzzzxxyxzzyzyyyzzxzyyxyxxxGGGEEEEEEEEEHooke’sLawforIsotropicMaterialHooke’sLawforAnisotropicMaterialHooke’sLawforOrthotropicMaterialzzxxxzzzyyyzyyxxxyEEEEEE264.4.6ANSYS材料模式ANSYSMaterialModels材料分類材料模式名稱非黏滯性材料彈性線性線性彈性材料非線性非線性彈性材料超彈性材料塑性塑性材料黏滯性材料彈性線性線性黏彈材料非線性非線性黏彈材料塑性黏塑性材料27第4.5節材料的破壞準則FailureCriteriaofMateris284.5.1延展性與脆性材料Ductilevs.BrittleDuctileMaterialStrainStressStrainStressBrittleMaterial294.5.2脆性材料的破壞準則FailureCriteriaforBrittleMaterialsMaximumPrincipalStressFailureCriteria:•Fracturewilloccurwhentensilestressisgreaterthanultimatetensilestrength,i.e.,u1304.5.3延展性材料的破壞準則(1/2)FailureCriteriaforDuctileMaterialsTrescaFailureCriteria:•Yieldingwilloccurwhenshearstressisgreaterthanshearyieldstrength,i.e.,2231yy31or314.5.3延展性材料的破壞準則(2/2)FailureCriteriaforDuctileMaterialsvonMisesFailureCriteria:•YieldingwilloccurwhenthevonMisesstressisgreaterthanyieldstrength,i.e.,ye2132322212132第4.6節實例:動態分析Example:DynamicAnalysis334.6.1問題描述yH=10mmP=100NQ=1MPaxL=60mmW=6mmMaterialE=200Gpa=0.3TimeLoad0344.4.2ANSYS分析程序(1/6)0102030405060708091011121314151617181920FINISH/CLEARL=0.060H=0.010B=0.006E=200E9NU=0.3RO=7850DMP=0.0001SIZE=0.003Q=1E6P=100/PREP7K,1,0,-H/2,-B/2K,2,0,H/2,-B/2K,3,0,H/2,B/2K,4,0,-H/2,B/22122232425262728293031323334353637383940K,5,L,-H/2,-B/2K,6,L,H/2,-B