转向系统建模和模态分析规范

Q/SZJ191001-2017转向系统建模和模态分析规范SpecificationofModelingandModalAnalysisForSteeringsystem20XX20XX-09-30实施20XX-08-28发布XXXX汽车工程技术有限公司发布Q/SZXX-X-2017转向系统建模和模态分析规范范围本标准规定了术语和定义、转向系统建模和模态分析方法及结果处理方法。本标准适用于CAE部门转向系统建模和模态分析规范。规范性引用文件无。术语和定义无。摘要Abstract汽车转向系统是用来改变或保持汽车行驶或倒退方向的一系列装置，汽车转向系统的功能就是按照驾驶员的意愿控制汽车的行驶方向。汽车转向系统对汽车的行驶安全至关重要。本文描述转向系统的建模和模态分析规范。Vehiclesteeringsystemisusedtochangeoraseriesofdevicestokeepthecarorthereversedirection.Thefunctionoftheautomobilesteeringsystemisinthedirectionoftheintendtocontrolthemotionofthecardriver.Vehiclesteeringsystemisessentialtothecardrivingsafety.Thisspecificationdescribesthemodelingandmodalanalysismethodofsteeringsystem.流程图ProcessFlowDiagram转向系统转向系统CAD模型SteeringsysteminWhiteCADmodel建模BuildFEmodel设置边界条件Defineconstraints/boundaryconditions计算SubmittoNastranorOptistruct处理输出文件Dealwiththeoutputfiletogettheresults结果是否满足要求Istheresultsok?结束EndYES优化OptimizationNO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):MSC.Nastran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) 牛顿(N)质量(Mass) 吨(Ton)长度(Length) 毫米(mm)时间(Time) 秒(Second)内容Contents转向系统包括转向管柱和方向盘。Steeringsystemincludesteeringcolumnandsteeringwheel.图2转向系统Figure2Steeringsystem坐标系CoordinateSystems分析采用整车坐标系，有些弹簧需要建局部坐标系。Analysisusesvehicleglobalcoordinatesystem,LocalcoordinatesystemsareneededforsomespringsintheSteeringandCCB.globalcoordinatesystem.建模技巧ModelingTechniques网格质量要求，平均单元尺寸3-8mm，翘曲小于12°，雅克比大于0.6，三角形单元数量小于10%。局部应力区域没有三角形单元，关键安装点周围没有三角形单元。增加一圈washer在螺栓孔上。螺栓用Rbe2+Cbar单元或Rbe2+Rbe2单元模拟。焊缝用Penta焊缝类型模拟。万向节采用四面体单元。简化的建模技术：本节将从没有隔振器的转向轴进行描述。转向轴有以下组件：内、外两个轴，提供一个吸收能量的滑动机构。这些是结构构件。两个万向节。一个连接到转向柱轴，另一个连接转向齿轮。这些机构的末端也是结构成员。FOD声学密封圈，具有薄薄的一层橡胶外套，里面填充泡沫，这些通常不需要建模。图3转向轴Fig3Steeringshafts请参阅图4。要模拟万向节，本文档描述了如何定义局部坐标系。内轴和外轴通过RBE2单元把他们连接在一起，RBE2约束所有6自由度。两个内外轴之间用释放轴向转动的RBE2单元进行连接。主点在万向节接头的一侧,从点在轴的一侧。这将避免与万向节连接模型的依赖性冲突。使用CBEAM单元模拟内外轴，横截面赋予常规属性。FOD密封圈通常不建模。这部分已确认被取消，关于这部分的功能很难模拟。图4转向轴Fig4SteeringshaftsModal图5描述如何简化模型连接内外两个轴。转动轴机构的局部坐标系:定义一个局部坐标系，该坐标系统与两个轴的中线平行。本局部坐标系应与万向节共用同一坐标系。附件所有产生位移的节点都应附到局部坐标系下(cd=局部坐标系ID7)。如果用CBUSH单元来模拟轴向和扭转方向弹簧刚度,这个局部坐标系也是CBUSH单元坐标系。内外两个重叠的套筒，CBEAM模拟应该有一对重合网格。在本例中，3对连接单元仅显示为说明目的。实际的连接将取决于模型单元的大小。对于垂直于轴向方向的平移自由度，使用零长度RBE2单元连接两个轴。不能在这些连接网格上约束弯曲旋转。CBEAM单元已经模拟了内外轴的弯曲刚度。图5内外轴连接Fig5ConnectingtheInnerandOutShaftsoftheI-Shaft带有隔振器的轴有些轴采用隔振器，以减少或消除由于液压功率引起的结构噪声，转向系统嘶嘶声，发生在700–900Hz或者以上的频率范围。见图6。图6隔振器I-ShaftwithanIsolatorFig6Generation-1EpsilonSaab在这个例子中，隔振器轴和万向节之间。也可以在隔振器中间插入一根轴。转向轴与隔振器之间模拟如下。见图7。隔振器模型网格必须引用一个与转动轴轴线平行的局部坐标系，常见的两端为一根轴和一根万向节。使用cbush单元模拟隔振器。弹簧刚度由试验提供，需要提供弹簧轴向和扭转刚度值。图7转动轴与隔振器模拟Fig7SimulatinganIsolatoronanI-Shaft万向节采用BEAM单元或者RBE2单元模拟，RBE2单元释放轴向转动自由度。图8Beam与RBE2两种模拟方式Fig8TwoSimulationofBeamandRBE2Meshqualityrequirements:Averageelementsizeis3to8mm,Warpage<12,Jacobin>0.6，Triangleselementproportion<10%.Notrianglesinlocalstressconcentratedarea.Notriangularelementsaroundkeyfixpoints.Addonewasherattheboltholes.UseRbe2+CbarelementsorRbe2+Rbe2elementstosimulatebolts.UsePenta-typedweldtosimulatewelds.U-JointsusingCTETRAelement.SimplifiedModelingTechnique：ThissectionwillstartwithanI-Shaftwithnoisolatorelement.I-Shafthasthefollowingcomponents:Twoshafts,aninnerandouter,whichprovideaslidingmechanismtoabsorbenergy.Thesearestructuralmembers.TwoU-Joints.Oneconnectstothesteeringcolumnshaft,theothertothesteeringgear.Thesearemechanisms,buttheirendsarealsostructuralmembers.AFront-of-Dash(FOD)acousticseal,whichhasathinrubberouterbootthatisfilledwithfoam.ThisistypicallyNOTmodeled.RefertoFigure3.TosimulatetheU-Joints,ThisdocumentspecifieshowtheU-Jointlocalcoordinatesystemsshouldbeoriented.TheinnerandoutershaftsareconnectedtotheirrespectiveU-JointswithRBE2elementsthatconstrainall6DOFs(DegreesofFreedom).usezero-lengthRBE2elementstoconnectthetwoshafts.TheindependentgridwillbeontheU-Jointside,thedependentgridwillbeontheshaftside.ThiswillavoiddependencyconflictswiththeU-Jointmodels.UseCBEAMelementstorepresenttheinnerandoutershafts,evenwhenthecross-sectionpropertiesareconstant.TheFODsealistypicallyNOTmodeled.Thisparthasbeenidentifiedheretoeliminateanyconfusionaboutthefunctionalityofthispart.Figure4illustrateshowtheinnerandoutshaftsshouldbeconnectedforasimplifiedmodel.LocalcoordinatesystemfortheI-Shaftslidingmechanism:Definealocalcoordinatesystemthathasoneaxisparalleltothecenterlineofthetwoshafts.ThislocalcoordinatesystemshouldbecompatiblewiththoseoftheU-Joints.Thedisplacementsoftheattachmentgridsshouldbedefinedrelativetothelocalcoordinatesystem(CD=field7oftheGRIDentry).IfCBUSHelementsareusedfortheaxialandtorsionaldirectionsspringrates,thislocalcoordinatesystemisalsotheCBUSHelementcoordinatesystem.TheoverlappingCBEAMelementsoftheinnerandoutershaftsshouldhavepairsofcoincidentgrids.Inthisexample,3pairsofcoincidentgridsareshownforillustrativepurposesonly.Theactualnumberwilldependonthesizeofthebarelements.ForthetranslationalDOFsperpendiculartotheaxialdirection,usezero-lengthRBE2elementstoconnectthetwoshafts.DoNOTconstrainthebendingrotationsattheseconnectiongrids.TheCBEAMelementsalreadysimulatethebendingstiffnessratesoftheinnerandoutershafts.I-ShaftswithanIsolatorSomeI-Shaftsuseanisolatortoreduceoreliminatestructure-bornenoiseduetohydraulicpowersteeringsystemhiss,whichoccursatorabovethe700–900Hzfrequencyrange.SeeFigure5.Inthisexample,theisolatorisbetweenashaftandaU-Joint.Itisalsopossibletoinserttheisolatorinthemiddleofoneoftheshafts.AnisolatoronanI-Shaftshouldbesimulatedasfollows.SeeFigure6.Theisolatorgridsmustreferencealocalcoordinatesystemthathasoneaxisparalleltothecommonaxesoftheendsof(a)thetwoshaftsor(b)theshaftandU-Joint.UseaCBUSHelementtorepresenttheisolator.Springstiffnessisprovidedbytestandtheneedtoprovidespringaxialandtorsionalrigidityvalue.UsebeamelementsorRbe2elementstosimulateU-Joints.假设和限制Assumptions/Limitations假设AssumptionsNA限制LimitationsN/A载荷和边界条件Loads/BoundaryConditions约束和边界条件Constraints/BoundrayConditions自由状态。载荷LoadsN/A结果Results结果格式ResultsFormats输出位移和振型云图。OutputDisplacementsandModeShapes.相关测试CorrelationTestsN/A性能要求PerformanceRequirements正常模型检查应包括两个轴（内部和外部），滑动机构，和隔振器。应核实以下内容：质量、重心、惯量值