复合扭力后轴疲劳分析规范

Q/SZJ191001-2017复合扭力后轴疲劳分析规范SpecificationofFatigueAnalysisforCompoundCrankRearAxles20XX20XX-XX-XX实施20XX-XX-XX发布XXXX汽车工程技术有限公司发布Q/SZXX-X-2017复合扭力后轴疲劳分析规范范围本标准规定了汽车复合扭力后轴疲劳分析的方法及要求。本标准适用于CAE部门汽车复合扭力后轴疲劳分析。规范性引用文件无。术语和定义无。摘要Abstract本流程根据应变-寿命理论，描述了复合扭力后轴裂纹萌生的疲劳分析。Thisproceduredescribescrackinitiationfatigueanalysisaccordingtothestrain-lifeconceptforcompoundcrankrearaxles.以下给出了流程图并阐述部件疲劳分析的典型方法。Theprocessflowdiagramisgivenbelowandrepresentsatypicalwaytoanalysesacomponentconcerningtofatiguelife.图1复合扭力后轴有限元模型Fig1CompoundCrankRearAxlesFEA流程图ProcessFlowDiagramGatherinputforstrengthanalysisTargetReached?PreparatoryworkonmodelGatherinputforstrengthanalysisTargetReached?PreparatoryworkonmodelPreparatoryworkonmaterialPreparatoryworkonloadingDocumentandreportRunfatigueanalysisPreparefiniteelementmodelaccordingthegeneralmodellingguidelines.Editinputfileforfatigueanalysis.Carryoutalinearelasticstressfiniteelementanalysis.根据通用的建模指南，准备有限元分析模型，编辑疲劳分析输入文件。完成线弹性有限元应力分析Ifnecessary,addcyclicmaterialpropertiesintomaterialdatabase.如有必要，增加循环材料属性在材料数据库中。Importhistoriesintoloadingdatabase.将载荷历程导入到载荷数据库中。Associatematerialaccordingtothedifferentmaterialsinthestructure.根据结构中不同的材料关联材料。Associatethefiniteelementloadswiththeirtimevariations.Customizeloadingunits,scalingandoffset.关联有限元载荷时间的历程。适配单位载荷，缩放偏移。Ifdesired,createspecialelementgroupsofinterest.如果期望，可以创建感兴趣的特殊单元组。Selectstrain-lifefatigueanalysis.UseSmith-Watson-Toppermeanstresscorrection.SelectNeuberplasticitycorrection.Activateabiaxialitycheck.Performfatigueanalysisonelementsusingaveragingformaximumabsoluteprincipals。选择应变-寿命疲劳分析，使用SWT平均应力修正。选择Neuber塑性修正，激活二轴率检查。使用单元平均绝对值最大主应力开展疲劳分析。Checkdamagemodelatthecriticalareas.Ascertainservicelife.Modifymodel,ifnecessary.检查模型危险区域的损伤值。确定服役寿命。如有必要，修改模型Reportonanalysis.Documentwithdamagecontourplot.编写报告，记录损伤云图。图2流程图Fig2ProcessFlowDiagram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(N)质量(Mass) 吨(Ton)长度(Length) 毫米(mm)时间(Time) 秒(Second)内容Contents本流程用线弹性分析叠加有限元模型，用E-N方法计算疲劳。载荷本身的获取不是本流程的主题。载荷历程通过全或半解析的方法得到。半解析的方法通过测量轮心载荷，作为多体系统分析MBS的输入，输出复合后轴连接点的载荷历程。全解析的方法不需要在轮心测量，但是需要创建数字输入。疲劳模型与结构分析模型没有什么不同。Thisprocedureuseslinearelasticstressanalysisforsuperpositiononthefiniteelementsideandthestrain-lifeapproachforfatiguecalculations.Theloadingacquisitionitselfisnotatopicofthisprocedure.Loadinghistoriescanbeobtainedinafull-orsemi-analyticalway.Thesemi-analyticalwaytakesmeasuredloadsatthewheelcentersasinputforamultibodysystemanalysisandoutputsloadinghistoriesatthecouplingpointsofthecompoundcrankrearaxle.Thefullyanalyticalapproachdoesnotneedmeasurementsatthewheelcentersbutbuilduptheinputdigitally.坐标系CoordinateSystems有限元单元坐标系和载荷坐标系都是全局坐标系：+X：整车纵向从前到后；+Y:侧向从驾驶员到副驾驶；+Z：垂向从底部到顶部。Thefiniteelementcoordinatesystemandtheloadingcoordinatesystemareboththeglobalonewith:+X:longitudinallyfromfronttorearofthevehicle;+Y:laterallyfromdrivertopassenger(forlefthanddrive);+Z:verticallyfrombottomtotop.建模技巧ModelingTechniques7.4.1后桥的CAD信息应包含以下内容：各部件的钣金件及焊点，焊缝位置；各部件的钣金和焊缝材料属性；CADinformationoftheRearAxlesstructure:Sheetmetalpartsandtheirspotandseamposition;Materialpropertiesofsheetmetalcomponentsandseam;7.4.2根据车身和其他部件的结构设计，应用不同的单元类型建立有限元模型。如部件是钣金件，用壳单元模拟；如是铸造，则使用实体单元。如是焊缝，用壳单元建模。Thetypeofelementusedtomodelthebody-in-whiteoranyotherstructuredependsonitsdesign.Ifthecomponentisstampedfromsheetmetal,itshouldbemodeledusingshellelements.Ifitisforgedorcast,thensolidelementsshouldbeused.Ifitisseam,itshouldbemodeledusingshellelements.假设和限制Assumptions/Limitations假设Assumptions就应力计算而言：Asfarasstresscalculationsareconcerned:习惯性使用线弹性理论（NASTRANSOL101求解器）；Customaryassumptionsofthelineartheoryofelasticityareused(NASTRANSol101);材料的性能是在室温下测定的。Materialperformanceistestedatroomtemperature.限制Limitations自然的，疲劳是随机的，载荷历程受驾驶员，路面和天气条件的影响，材料特性受自造过程的影响，模拟受模型的影响等。Bynature,fatigueisstochastic:loadinghistoriesareinfluencedbydriver,roadandweatherconditions,materialpropertiesareinfluencedbythemanufacturingprocess,simulationisinfluencedbythemodellingetc.载荷和边界条件Loads/BoundaryConditions约束Constrain使用惯性释放来模拟地面激励Forprovinggroundsimulationinertiareliefisperformed.载荷Load当完成一次地面激励，有35个单一力和扭矩作用在复合后轴上Whenperformingaprovinggroundsimulation35singleforcesandmomentsactonthecompoundcrankrearaxle.ForcesFForcesFx,Fy,FuapplyattheA-bushing(Fabs)thebumpstopmount(Fbsm),theshockabsorbermount(Fsam)andthespringseatmount(Fssm)ForcesFx,Fy,andFzandmomentsMx,My,andMzactonthewheelcenter(Fwhc)力Fx,Fy,Fz作用在A-衬套（Fabs）缓冲块安装点（Fbsm）减震器支柱安装点（Fsam）弹簧座安装点（Fssm）力Fx,Fy,Fz和扭矩Mx,My,Mz作用在车轮中心（Fwhc）图3载荷和边界Fig3Load&BoundaryConditions结果Results在提交nCode的计算文件格式为*.flo，结果文件为*.hyp。TheformatofresolvefilefornCodeis*.flo,theformatofresultfileis*.hyp.为了便于重复使用，下列的输入文件应存盘并确保可用。Forrepeatability,allinputfilesmustbekept.Forconvenience,allthefollowingfilesshouldremainavailable:jobname.dat MSC