ansys工程分析15.ppt

ansys工程分析15.ppt

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Chapter15結構動力分析StructuralDynamicAnalysisContents15.1何謂動力分析？

WhatAreDynamicAnalyses?

15.2解題方法SolutionMethods15.3質量與阻尼MassandDamping15.4實例：

圓柱形子彈的撞擊模擬Example:

CopperCylinderImpactingonaRigidWall15.5動態負載DynamicLoads15.6初始條件InitialConditions15.7積分時間間隔IntegrationTimeSteps15.8練習題：

火箭的飛行Exercise:

RocketFlight2第15.1節何謂動力分析？

WhatAreDynamicAnalyses?

3DynamicEffectsInertiaforceDampingforceElasticForceExternalforceDynamicEffects415.1.1TransientDynamicAnalysis515.1.2ModalAnalysis（1/3）615.1.2ModalAnalysis（2/3）715.1.2ModalAnalysis（3/3）AvoidresonanceExploitresonanceAssessstructuralstiffnessStructuralmodaldegreesoffreedomFurtherdynamicanalysesetc.815.1.3HarmonicResponseAnalysis9第15.2節解題方法SolutionMethods10SolutionMethodsSolutionMethodsforEquationofMotionDirectIntegrationModeSuperpositionImplicitExplicitReduceFullFullReduce1115.2.1DirectIntegrationImplicitmethod（ANSYS）Explicitmethod（LS-DYNA）1215.2.2Implicitvs.ExplicitMethodsImplicitmethodExplicitmethod1315.2.3ModeSuperpositionMethod1415.2.4ReducedMethodwhere1515.2.5MethodsforNonlinearDynamicAnalysisFornonlinearanalysis,theonlymethodsapplicableisDIRECTINTEGRATIONmethod.Reducedmethodcannotbeusedfornonlinearanalysis.Eitherimplicitorexplicitmethodscanbeused.16第15.3節質量與阻尼MassandDamping1715.3.1Consistentvs.LumpedMassMatricesConsistentmassmatrixLumpedmassmatrix1815.3.2DampingDampingeffectsisthetotalofallenergydissipationmechanismsHysteresis（soliddamping）ViscousdampingDry-friction（Coulombdamping）1915.3.3IdealizationofStructuralDampingStructuraldampingsareusuallysmall（2%-7%）.EquivalentviscousdampingisassumedinANSYS,i.e.,2015.3.4HowANSYSFormsDampingMatrix?

AlphadampingBetadampingMaterialdependentbetadampingElementdampingmatricesFrequency-dependentdampingmatrix21第15.4節實例:

圓柱型子彈的撞擊模擬CopperCylinderImpactingonaRigidWall2215.4.1ProblemDescriptionxyLDInitialVelocityVo2315.4.2ModelingConsiderationMaterial:

bilinearplasticmodel.VISCO106（2Dviscoplasticsolid）isused.Useaxisymmetricmodel.2415.4.3ANSYSProcedure（1/4）010203040506070809101112131415161718192021FINISH/CLEAR/TITLE,UNITS:

SI/PREP7ET,1,VISCO106,1MP,EX,1,117E9MP,NUXY,1,0.35MP,DENS,1,8930TB,BISO,1TBDATA,400E6,100E6TBPLOT,BISO,1RECTNG,0,0.0032,0,0.0324LESIZE,1,4LESIZE,2,20MSHAPE,0,2DMSHKEY,1AMESH,ALLFINISH2515.4.3ANSYSProcedure（2/4）2324252627282930313233343536373839404142/SOLUANTYPE,TRANSTRNOPT,FULLNLGEOM,ONIC,ALL,UY,0,-227NSEL,S,LOC,X,0D,ALL,UX,0NSEL,S,LOC,Y,0D,ALL,UY,0NSEL,ALL/PBC,U,ONEPLOTTIME,80E-6DELTIM,0.4E-6KBC,1OUTRES,ALL,4SOLVEFINISH2615.4.3ANSYSProcedure（3/4）4445464748495051525354555657/POST26TOPNODE=NODE（0,0.0324,0）NSOL,2,TOPNODE,U,Y,DISPDERIV,3,2,1,VELO/GRID,1/AXLAB,X,TIMEs/AXLAB,Y,DISPLACEMENTmPLVAR,2/AXLAB,Y,VELOCITYm/sPLVAR,3FINISH2715.4.3ANSYSProcedure（4/4）59606162636465/POST1SET,LASTPLDISP,2PLNSOL,EPTO,EQVANTIME,3028第15.5節動態負載DynamicLoads29DynamicLoads:

AnExample010203040506070809101112131415161718/SOLU.F,.!

22.5atthenodesTIME,0.5!

EndingtimeDELTIM,.!

IntegrationstepKBC,0!

RampedloadingAUTOTS,ON!

OptionOUTRES,.!

OptionSOLVE!

Loadstep1F,.!

10atthenodesTIME,1!

EndingtimeSOLVE!

Loadstep2FDELE,.!

ZerotheforceTIME,1.5!

EndingtimeKBC,1!

SteppedloadingSOLVE!

Loadstep300.51.01.5Time（s）Force（N）22.51030第15.6節初始條件InitialConditions3115.6.1Example:

AnStationaryPlateSubjectedtoanImpulseLoadThisisthedefaultinitialcondition.Noinputisneeded.3215.6.2Example:

InitialVelocityonaGolfClubHeadThissimpleinitialconditioncanbespecifiedbyusingICcommand.NSEL,ALLIC,ALL,UY,0,V03315.6.3Example:

PluckingaCantileverBeam0102030405060708091011121314/SOLUANTYPE,TRANS.TIMINT,OFF!

TransienteffectsoffTIME,0.001!

SmalltimeintervalD,.!

ApplydisplacementatdesirednodesKBC,1!

SteppedloadsNSUBST,2!

Toavoidnon-zerovelocitySOLVETIMINT,ON!

TransienteffectsonTIME,.!

ActualtimeatendofloadDDELE,.!

DeletetheapplieddisplacementSOLVE3415.6.4Example:

DroppinganObjectfromRest0102030405060708091011121314151617/SOLUTIMINT,OFF!

TransienteffectsoffTIME,0.001!

SmalltimeintervalNSEL,.!

SelectallnodesontheobjectD,ALL,ALL,0!

TemporarilyfixthemNSEL,ALLACEL,.!

ApplyaccelerationKBC,1!

SteppedloadsNSUBST,2!

Toavoidnon-zerovelocitySOLVE!

Loadstep1TIMINT,ON!

TransienteffectsonTIME,.!

ActualtimeatendofloadNSEL,.!

SelectallnodesontheobjectDDELE,ALL,ALL!

ReleasethemNSEL,ALLSOLVE!

Loadstep235第15.7節積分時間間隔IntegrationtimeSteps3615.7.1ResponseFrequencyResponseTimeMinimumresponsetime3715.7.2AbruptChangesinLoading00.51.01.5Time（s）Force（N）22.5103815.7.3ContactFrequency3915.7.4WavePropagation4015.8Exercise:

RocketFlighty140in.ThrustTime100lb1sec.12341