ABAQUS关于固有频率的提取方法

《ABAQUS关于固有频率的提取方法》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、Abaqus固有频率提取6.3.5 NaturalfrequencyextractionProducts: Abaqus/Standard  Abaqus/CAE  Abaqus/AMS  References·“Procedures:overview,” Section6.1.1·“Generalandlinearperturbationprocedures,” Section6.1.2·“Dynamicanalysisprocedures:overview,” Section6.3.1·*FREQUENCY·“Configuringafrequencyprocedure”in“Confi

2、guringlinearperturbationanalysisprocedures,” Section14.11.2oftheAbaqus/CAEUser'sManualOverviewThefrequencyextractionprocedure:·performseigenvalueextractiontocalculatethenaturalfrequenciesandthecorrespondingmodeshapesofasystem;·willincludeinitialstressandloadstiffnesseffectsduetopreloadsandinitialco

3、nditionsifgeometricnonlinearityisaccountedforinthebasestate,sothatsmallvibrationsofapreloadedstructurecanbemodeled;·willcomputeresidualmodesifrequested;·isalinearperturbationprocedure;·canbeperformedusingthetraditionalAbaqussoftwarearchitectureor,ifappropriate,thehigh-performanceSIMarchitecture(see

4、 “UsingtheSIMarchitectureformodalsuperpositiondynamicanalyses”in“Dynamicanalysisprocedures:overview,” Section6.3.1);and·solvestheeigenfrequencyproblemonlyforsymmetricmassandstiffnessmatrices;thecomplexeigenfrequencysolvermustbeusedifunsymmetriccontributions,suchastheloadstiffness,areneeded. Eigenva

5、lueextractionTheeigenvalueproblemforthenaturalfrequenciesofanundampedfiniteelementmodelis whereisthemassmatrix(whichissymmetricandpositivedefinite); isthestiffnessmatrix(whichincludesinitialstiffnesseffectsifthebasestateincludedtheeffectsofnonlineargeometry); istheeigenvector(themodeofvibration);an

6、d M and Naredegreesoffreedom. When  ispositivedefinite,alleigenvaluesarepositive.Rigidbodymodesandinstabilitiescause  tobeindefinite.Rigidbodymodesproducezeroeigenvalues.Instabilitiesproducenegativeeigenvaluesandoccurwhenyouincludeinitialstresseffects.Abaqus/Standardsolvestheeigenfrequencyproblemon

7、lyforsymmetricmatrices. SelectingtheeigenvalueextractionmethodAbaqus/Standardprovidesthreeeigenvalueextractionmethods:·Lanczos·Automaticmulti-levelsubstructuring(AMS),anadd-onanalysiscapabilityforAbaqus/Sta