准静态有限元法惯性反力部件疲劳分析规范

准静态有限元法惯性反力部件疲劳分析规范SpecificationforQuasi-StaticFiniteElementBasedDurabilityAnalysisofInertiallyReactedComponents20XX20XX-XX-XX实施20XX-XX-XX发布XXXX汽车工程技术有限公司发布准静态有限元法惯性反力部件疲劳分析规范范围本标准规定了术语和定义、准静态有限元惯性反力部件疲劳分析方法及结果处理方法。本标准适用于CAE部门惯性反力部件疲劳分析。规范性引用文件无。术语和定义无。摘要Abstract本文详细描述开展安装部件疲劳分析的规范。安装部件是指其主要的应力是由强制的运动和结构本身的质量导致的，而不是其承受的作用力。这种类型的部件也称为惯性反力部件（IRC）。本规范描述了使用静态叠加有限元分析（FEA）和疲劳软件评估由车辆运动激励导致的安装部件结构疲劳分析方法。典型的应用是悬臂梁、对加速度敏感的部件，如油箱和蓄电池托盘等。因为这些部件主要承受整车的加速度且一般不发生共振，可以通过使用惯性释放法来进行分析。其他影响结构疲劳的因素，如瞬态效应、热载荷和腐蚀等不在本规范的讨论范围内。Thisdocumentdetailsaprocedureforperformingmountedcomponentdurabilityanalysis.Amountedcomponentisdefinedasonewhosedominantstressesarecreatedbyenforcedmotionandthestructure’sownmass,ratherthanappliedforces.Thistypeofcomponentisalsoreferredtoasaninertiallyreactedcomponent(IRC).Thisproceduredescribesatechniquetoestimatethestructuraldurabilityofamountedcomponentexcitedbyvehiclemotionusingstaticsuperpositionfiniteelementanalysis(FEA)andfatiguesoftware.Typicalapplicationsarecantilevered,accelerationsensitivecomponents,suchasthefueltankandbatterytray.Becausethesecomponentsareprimarilyloadedbyoverallvehicleaccelerations,andtheytypicallydonotresonate,theycanbeanalyzedusinganinertiareliefmethod.Othereffectsthatinfluencestructuraldurabilitysuchastransienteffects,thermalloading,andcorrosionarenotcoveredbythisprocedure.流程图ProcessFlowDiagram有限元有限元线性分析FEAlinearanalysis建立疲劳分析模型Createfatigueinputfile运行疲劳分析Runfatigueanalysis损伤/寿命云图Damage/lifecontourplot结果是否满足要求？Aretheresultsmeettarget?建立有限元模型BuildFEAmodel记录存档编制报告Documentandreport是YES优化Optimization否NO材料疲劳属性Materialfatigueproperties载荷时间历程映射到FEA工况LoadtimehistorymappingtoFEAsubcases获取测量或解析的加速度载荷Obtainmeasuredoranalyticalaccelerations加速度载荷编辑/格式转换加速度Edit/formataccelerationsproperties通道处理Channelprocessing图1流程图Fig1ProcessFlowDiagram工具描述ToolDescription仿真分析过程中需要用到的如下软件:Thefollowingsoftwarefacilitatestheanalyticalsimulationprocess:前处理(Preprocessors):Hypermesh求解器(AnalysisCode):Nastran,nCode后处理(Postprocessors):Hyperview矩阵处理(Matrixmanipulation):Matlab建模和分析过程Modeling/AnalysisProcedure单位Units分析中所用单位制如下所示:Theunitsusedintheanalysisareasfollows:力(Force) 牛顿(N)质量(Mass) 吨(Ton)长度(Length) 毫米(mm)时间(Time) 秒(Second)内容Contents有限元模型应包括安装部件，包括导致惯性反力的质量以及提供载荷传递路径的结构或连接到惯性反力部件上的特殊结构。惯性反力部件的边界的应力场应较低，并且对较小的改动不敏感。TheFEMshouldincludethemountedcomponent,includingtherepresentativemassthatcausestheinertialreaction,aswellasanystructureprovidingsignificantloadpathsorproductionintendedstructuresthatareattachedtotheIRC.ThestressfieldshouldbelowattheboundaryandpeakvalueswithinoraroundtheIRC,anditshouldbeinsensitivetosmallchanges.坐标系CoordinateSystems除特殊说明，本规范一般使用整车坐标系。（X轴向后，Y轴向右，Z轴向上）Generally,theglobalvehiclesystemisused.Mathdataforthebody-in-whiteisdesignedinthevehiclecoordinatesystem(ie.X-axisrearward,Y-axisrightandZ-axisupward)建模技巧ModelingTechniques网格质量要求，平均单元尺寸10mm，翘曲小于12°，雅克比大于0.6，三角形单元数量小于10%。Meshqualityrequirements:Averageelementsizeis3to8mm,Warpage<12,Jacobin>0.6，Triangleselementproportion<10%.假设和限制Assumptions/Limitations假设Assumptions线性静力学分析使用小转动/小变形理论。Linearstaticanalysisisperformedusingthesmallangle/smalldeflectiontheory.缺口系数Kf=1，除非分析者有结果数据能给出另外的Kf建议值Thenotchfactor,Kf=1,unlesstheanalysthasresultsdatathatwouldsuggestanotherKf.限制Limitations本规范不包含瞬态动力学和热力学分析方法。Thisproceduredoesnotcovertransientdynamicorthermalanalysisapproaches.载荷和边界条件Loads/BoundaryConditions边界条件BoundaryConditions如果仿真台架试验，确保夹具限制的方向运动和仿真分析的约束相一致。对于给定的夹具位置，确定部件的自由度(DOF)。除此之外，建立夹具位置的部件自由度的构图，以便于更容易理解边界约束。Ifsimulatingatest,ensurethattheconstraintsareconsistentwiththedirectionalmovementlimitationscausedbyfixtures.Foreachgivenfixturelocation,determinethedegreesoffreedom(DOF)onthecomponent.Additionally,createaschematicofthecomponentandtheDOFateachfixturelocationsothattheboundaryconstraintsareeasilyunderstood.下面的例子中，三个作动器在车架截面和接附的油箱的Z向施加运动。图2中这些输入以黄色箭头给出。另外夹具约束车架的X和Y向运动。在构图中这些夹具用红色圆圈表达并详细说明了其自由度。Inthisexample,threeactuatorsapplymotionintheZdirectiontotheframesectionandattachedfueltank.TheseinputsarepicturedinFig2withthreeyellowarrows.Additionally,therearefixturesthatconstraintheframeintheXandYdirectionsbyhorizontalpivotrods.ThesefixturesarerepresentedwithredcirclesandtheirDOFaredetailedontheschematic.Independent:TestFixtureDependent:FrameRelationship:23456DOFIndependent:TestFixtureDependent:FrameRelationship:13456DOFIndependent:TestFixtureDependent:FrameRelationship:13456DOFIndependent:TestFixtureDependent:FrameRelationship:23456DOFIndependent:TestFixtureDependent:FrameRelationship:13456DOFIndependent:TestFixtureDependent:FrameRelationship:13456DOF图2构图示例Fig2Exampleofschematic载荷Loads输入数据一般有几种类型（比如加速度，力等）。通常，输入数据是测量或解析的加速度值，需要转换。对于惯性释放分析，输入数据必须力。以下是将加速度转换成力的方法。Inputdatamaybeprovidedindifferentquantities(i.e.acceleration,force,etc.).Typically,inputdatawillbeeithermeasuredoranalyticalaccelerations,andaconversionisrequired.Forinertiareliefanalysis,theinputmustbeinforceunits.Aprocedureforconversionofaccelerationtoforceunitsfollows.图3加速度输入数据Fig3AccelerationinputdataNOTE:A在每个输入位置的建立一个CELAS单元并在弹簧的端点附加一个单位质量。（见图4）CreateaCELASwithaunitmassattheendofthespringateachinputlocation.(SeeFig.4)图4CELAS弹簧单元Fig4CELASwithspring在每个输入位置施加1N的作用力。Apply1Nforceateachinputlocation.使用惯性释放法计算模型，获取每个工况下每个输入点的弹簧力。Runthemodelusinginertiareliefandrecovertheforceinthespringateachinputlocationforeachloadcase.知道弹簧力后就可以推算出每个输入位置质量单元的加速度。Knowingthespringforceyoucandeducethemassaccelerationateachinputlocation.可以计算出加速度矩阵Aspring。Aspring是集中质量矩阵Amass的逆矩阵。ThiscreatesanaccelerationmatrixAspring.Aspringistheinverseofthecondensedmassmatrix,Amass.NOTE:Aspring=a11加速度矩阵等于弹簧加速度矩阵乘以