Q/SZJ191001-2017轉(zhuǎn)向系統(tǒng)建模和模態(tài)分析規(guī)范SpecificationofModelingandModalAnalysisForSteeringsystem20XX20XX-09-30實施20XX-08-28發(fā)布XXXX汽車工程技術有限公司發(fā)布Q/SZXX-X-2017轉(zhuǎn)向系統(tǒng)建模和模態(tài)分析規(guī)范范圍本標準規(guī)定了術語和定義、轉(zhuǎn)向系統(tǒng)建模和模態(tài)分析方法及結(jié)果處理方法。本標準適用于CAE部門轉(zhuǎn)向系統(tǒng)建模和模態(tài)分析規(guī)范。規(guī)范性引用文件無。術語和定義無。摘要Abstract汽車轉(zhuǎn)向系統(tǒng)是用來改變或保持汽車行駛或倒退方向的一系列裝置，汽車轉(zhuǎn)向系統(tǒng)的功能就是按照駕駛員的意愿控制汽車的行駛方向。汽車轉(zhuǎn)向系統(tǒng)對汽車的行駛安全至關重要。本文描述轉(zhuǎn)向系統(tǒng)的建模和模態(tài)分析規(guī)范。Vehiclesteeringsystemisusedtochangeoraseriesofdevicestokeepthecarorthereversedirection.Thefunctionoftheautomobilesteeringsystemisinthedirectionoftheintendtocontrolthemotionofthecardriver.Vehiclesteeringsystemisessentialtothecardrivingsafety.Thisspecificationdescribesthemodelingandmodalanalysismethodofsteeringsystem.流程圖ProcessFlowDiagram轉(zhuǎn)向系統(tǒng)轉(zhuǎn)向系統(tǒng)CAD模型SteeringsysteminWhiteCADmodel建模BuildFEmodel設置邊界條件Defineconstraints/boundaryconditions計算SubmittoNastranorOptistruct處理輸出文件Dealwiththeoutputfiletogettheresults結(jié)果是否滿足要求Istheresultsok?結(jié)束EndYES優(yōu)化OptimizationNO圖1流程圖Fig1ProcessFlowDiagram工具描述ToolDescription仿真分析過程中需要用到的如下軟件:Thefollowingsoftwarefacilitatestheanalyticalsimulationprocess:前處理(Preprocessors):Hypermesh求解器(AnalysisCode):MSC.Nastran后處理(Postprocessors):Hyperview建模和分析過程Modeling/AnalysisProcedure單位Units分析中所用單位制如下所示:Theunitsusedintheanalysisareasfollows:力(Force) 牛頓(N)質(zhì)量(Mass) 噸(Ton)長度(Length) 毫米(mm)時間(Time) 秒(Second)內(nèi)容Contents轉(zhuǎn)向系統(tǒng)包括轉(zhuǎn)向管柱和方向盤。Steeringsystemincludesteeringcolumnandsteeringwheel.圖2轉(zhuǎn)向系統(tǒng)Figure2Steeringsystem坐標系CoordinateSystems分析采用整車坐標系，有些彈簧需要建局部坐標系。Analysisusesvehicleglobalcoordinatesystem,LocalcoordinatesystemsareneededforsomespringsintheSteeringandCCB.globalcoordinatesystem.建模技巧ModelingTechniques網(wǎng)格質(zhì)量要求，平均單元尺寸3-8mm，翹曲小于12°，雅克比大于0.6，三角形單元數(shù)量小于10%。局部應力區(qū)域沒有三角形單元，關鍵安裝點周圍沒有三角形單元。增加一圈washer在螺栓孔上。螺栓用Rbe2+Cbar單元或Rbe2+Rbe2單元模擬。焊縫用Penta焊縫類型模擬。萬向節(jié)采用四面體單元。簡化的建模技術：本節(jié)將從沒有隔振器的轉(zhuǎn)向軸進行描述。轉(zhuǎn)向軸有以下組件：內(nèi)、外兩個軸，提供一個吸收能量的滑動機構。這些是結(jié)構構件。兩個萬向節(jié)。一個連接到轉(zhuǎn)向柱軸，另一個連接轉(zhuǎn)向齒輪。這些機構的末端也是結(jié)構成員。FOD聲學密封圈，具有薄薄的一層橡膠外套，里面填充泡沫，這些通常不需要建模。圖3轉(zhuǎn)向軸Fig3Steeringshafts請參閱圖4。要模擬萬向節(jié)，本文檔描述了如何定義局部坐標系。內(nèi)軸和外軸通過RBE2單元把他們連接在一起，RBE2約束所有6自由度。兩個內(nèi)外軸之間用釋放軸向轉(zhuǎn)動的RBE2單元進行連接。主點在萬向節(jié)接頭的一側(cè),從點在軸的一側(cè)。這將避免與萬向節(jié)連接模型的依賴性沖突。使用CBEAM單元模擬內(nèi)外軸，橫截面賦予常規(guī)屬性。FOD密封圈通常不建模。這部分已確認被取消，關于這部分的功能很難模擬。圖4轉(zhuǎn)向軸Fig4SteeringshaftsModal圖5描述如何簡化模型連接內(nèi)外兩個軸。轉(zhuǎn)動軸機構的局部坐標系:定義一個局部坐標系，該坐標系統(tǒng)與兩個軸的中線平行。本局部坐標系應與萬向節(jié)共用同一坐標系。附件所有產(chǎn)生位移的節(jié)點都應附到局部坐標系下(cd=局部坐標系ID7)。如果用CBUSH單元來模擬軸向和扭轉(zhuǎn)方向彈簧剛度,這個局部坐標系也是CBUSH單元坐標系。內(nèi)外兩個重疊的套筒，CBEAM模擬應該有一對重合網(wǎng)格。在本例中，3對連接單元僅顯示為說明目的。實際的連接將取決于模型單元的大小。對于垂直于軸向方向的平移自由度，使用零長度RBE2單元連接兩個軸。不能在這些連接網(wǎng)格上約束彎曲旋轉(zhuǎn)。CBEAM單元已經(jīng)模擬了內(nèi)外軸的彎曲剛度。圖5內(nèi)外軸連接Fig5ConnectingtheInnerandOutShaftsoftheI-Shaft帶有隔振器的軸有些軸采用隔振器，以減少或消除由于液壓功率引起的結(jié)構噪聲，轉(zhuǎn)向系統(tǒng)嘶嘶聲，發(fā)生在700–900Hz或者以上的頻率范圍。見圖6。圖6隔振器I-ShaftwithanIsolatorFig6Generation-1EpsilonSaab在這個例子中，隔振器軸和萬向節(jié)之間。也可以在隔振器中間插入一根軸。轉(zhuǎn)向軸與隔振器之間模擬如下。見圖7。隔振器模型網(wǎng)格必須引用一個與轉(zhuǎn)動軸軸線平行的局部坐標系，常見的兩端為一根軸和一根萬向節(jié)。使用cbush單元模擬隔振器。彈簧剛度由試驗提供，需要提供彈簧軸向和扭轉(zhuǎn)剛度值。圖7轉(zhuǎn)動軸與隔振器模擬Fig7SimulatinganIsolatoronanI-Shaft萬向節(jié)采用BEAM單元或者RBE2單元模擬，RBE2單元釋放軸向轉(zhuǎn)動自由度。圖8Beam與RBE2兩種模擬方式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.假設和限制Assumptions/Limitations假設AssumptionsNA限制LimitationsN/A載荷和邊界條件Loads/BoundaryConditions約束和邊界條件Constraints/BoundrayConditions自由狀態(tài)。載荷LoadsN/A結(jié)果Results結(jié)果格式ResultsFormats輸出位移和振型云圖。OutputDisplacementsandModeShapes.相關測試CorrelationTestsN/A性能要求PerformanceRequirements正常模型檢查應包括兩個軸（內(nèi)部和外部），滑動機構，和隔振器。應核實以下內(nèi)容：質(zhì)量、重心、慣量值