準靜態(tài)有限元法慣性反力部件疲勞分析規(guī)范SpecificationforQuasi-StaticFiniteElementBasedDurabilityAnalysisofInertiallyReactedComponents20XX20XX-XX-XX實施20XX-XX-XX發(fā)布XXXX汽車工程技術(shù)有限公司發(fā)布準靜態(tài)有限元法慣性反力部件疲勞分析規(guī)范范圍本標(biāo)準規(guī)定了術(shù)語和定義、準靜態(tài)有限元慣性反力部件疲勞分析方法及結(jié)果處理方法。本標(biāo)準適用于CAE部門慣性反力部件疲勞分析。規(guī)范性引用文件無。術(shù)語和定義無。摘要Abstract本文詳細描述開展安裝部件疲勞分析的規(guī)范。安裝部件是指其主要的應(yīng)力是由強制的運動和結(jié)構(gòu)本身的質(zhì)量導(dǎo)致的，而不是其承受的作用力。這種類型的部件也稱為慣性反力部件（IRC）。本規(guī)范描述了使用靜態(tài)疊加有限元分析（FEA）和疲勞軟件評估由車輛運動激勵導(dǎo)致的安裝部件結(jié)構(gòu)疲勞分析方法。典型的應(yīng)用是懸臂梁、對加速度敏感的部件，如油箱和蓄電池托盤等。因為這些部件主要承受整車的加速度且一般不發(fā)生共振，可以通過使用慣性釋放法來進行分析。其他影響結(jié)構(gòu)疲勞的因素，如瞬態(tài)效應(yīng)、熱載荷和腐蝕等不在本規(guī)范的討論范圍內(nèi)。Thisdocumentdetailsaprocedureforperformingmountedcomponentdurabilityanalysis.Amountedcomponentisdefinedasonewhosedominantstressesarecreatedbyenforcedmotionandthestructure’sownmass,ratherthanappliedforces.Thistypeofcomponentisalsoreferredtoasaninertiallyreactedcomponent(IRC).Thisproceduredescribesatechniquetoestimatethestructuraldurabilityofamountedcomponentexcitedbyvehiclemotionusingstaticsuperpositionfiniteelementanalysis(FEA)andfatiguesoftware.Typicalapplicationsarecantilevered,accelerationsensitivecomponents,suchasthefueltankandbatterytray.Becausethesecomponentsareprimarilyloadedbyoverallvehicleaccelerations,andtheytypicallydonotresonate,theycanbeanalyzedusinganinertiareliefmethod.Othereffectsthatinfluencestructuraldurabilitysuchastransienteffects,thermalloading,andcorrosionarenotcoveredbythisprocedure.流程圖ProcessFlowDiagram有限元有限元線性分析FEAlinearanalysis建立疲勞分析模型Createfatigueinputfile運行疲勞分析Runfatigueanalysis損傷/壽命云圖Damage/lifecontourplot結(jié)果是否滿足要求？Aretheresultsmeettarget?建立有限元模型BuildFEAmodel記錄存檔編制報告Documentandreport是YES優(yōu)化Optimization否NO材料疲勞屬性Materialfatigueproperties載荷時間歷程映射到FEA工況LoadtimehistorymappingtoFEAsubcases獲取測量或解析的加速度載荷Obtainmeasuredoranalyticalaccelerations加速度載荷編輯/格式轉(zhuǎn)換加速度Edit/formataccelerationsproperties通道處理Channelprocessing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):Nastran,nCode后處理(Postprocessors):Hyperview矩陣處理(Matrixmanipulation):Matlab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有限元模型應(yīng)包括安裝部件，包括導(dǎo)致慣性反力的質(zhì)量以及提供載荷傳遞路徑的結(jié)構(gòu)或連接到慣性反力部件上的特殊結(jié)構(gòu)。慣性反力部件的邊界的應(yīng)力場應(yīng)較低，并且對較小的改動不敏感。TheFEMshouldincludethemountedcomponent,includingtherepresentativemassthatcausestheinertialreaction,aswellasanystructureprovidingsignificantloadpathsorproductionintendedstructuresthatareattachedtotheIRC.ThestressfieldshouldbelowattheboundaryandpeakvalueswithinoraroundtheIRC,anditshouldbeinsensitivetosmallchanges.坐標(biāo)系CoordinateSystems除特殊說明，本規(guī)范一般使用整車坐標(biāo)系。（X軸向后，Y軸向右，Z軸向上）Generally,theglobalvehiclesystemisused.Mathdataforthebody-in-whiteisdesignedinthevehiclecoordinatesystem(ie.X-axisrearward,Y-axisrightandZ-axisupward)建模技巧ModelingTechniques網(wǎng)格質(zhì)量要求，平均單元尺寸10mm，翹曲小于12°，雅克比大于0.6，三角形單元數(shù)量小于10%。Meshqualityrequirements:Averageelementsizeis3to8mm,Warpage<12,Jacobin>0.6，Triangleselementproportion<10%.假設(shè)和限制Assumptions/Limitations假設(shè)Assumptions線性靜力學(xué)分析使用小轉(zhuǎn)動/小變形理論。Linearstaticanalysisisperformedusingthesmallangle/smalldeflectiontheory.缺口系數(shù)Kf=1，除非分析者有結(jié)果數(shù)據(jù)能給出另外的Kf建議值Thenotchfactor,Kf=1,unlesstheanalysthasresultsdatathatwouldsuggestanotherKf.限制Limitations本規(guī)范不包含瞬態(tài)動力學(xué)和熱力學(xué)分析方法。Thisproceduredoesnotcovertransientdynamicorthermalanalysisapproaches.載荷和邊界條件Loads/BoundaryConditions邊界條件BoundaryConditions如果仿真臺架試驗，確保夾具限制的方向運動和仿真分析的約束相一致。對于給定的夾具位置，確定部件的自由度(DOF)。除此之外，建立夾具位置的部件自由度的構(gòu)圖，以便于更容易理解邊界約束。Ifsimulatingatest,ensurethattheconstraintsareconsistentwiththedirectionalmovementlimitationscausedbyfixtures.Foreachgivenfixturelocation,determinethedegreesoffreedom(DOF)onthecomponent.Additionally,createaschematicofthecomponentandtheDOFateachfixturelocationsothattheboundaryconstraintsareeasilyunderstood.下面的例子中，三個作動器在車架截面和接附的油箱的Z向施加運動。圖2中這些輸入以黃色箭頭給出。另外夾具約束車架的X和Y向運動。在構(gòu)圖中這些夾具用紅色圓圈表達并詳細說明了其自由度。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圖2構(gòu)圖示例Fig2Exampleofschematic載荷Loads輸入數(shù)據(jù)一般有幾種類型（比如加速度，力等）。通常，輸入數(shù)據(jù)是測量或解析的加速度值，需要轉(zhuǎn)換。對于慣性釋放分析，輸入數(shù)據(jù)必須力。以下是將加速度轉(zhuǎn)換成力的方法。Inputdatamaybeprovidedindifferentquantities(i.e.acceleration,force,etc.).Typically,inputdatawillbeeithermeasuredoranalyticalaccelerations,andaconversionisrequired.Forinertiareliefanalysis,theinputmustbeinforceunits.Aprocedureforconversionofaccelerationtoforceunitsfollows.圖3加速度輸入數(shù)據(jù)Fig3AccelerationinputdataNOTE:A在每個輸入位置的建立一個CELAS單元并在彈簧的端點附加一個單位質(zhì)量。（見圖4）CreateaCELASwithaunitmassattheendofthespringateachinputlocation.(SeeFig.4)圖4CELAS彈簧單元Fig4CELASwithspring在每個輸入位置施加1N的作用力。Apply1Nforceateachinputlocation.使用慣性釋放法計算模型，獲取每個工況下每個輸入點的彈簧力。Runthemodelusinginertiareliefandrecovertheforceinthespringateachinputlocationforeachloadcase.知道彈簧力后就可以推算出每個輸入位置質(zhì)量單元的加速度。Knowingthespringforceyoucandeducethemassaccelerationateachinputlocation.可以計算出加速度矩陣Aspring。Aspring是集中質(zhì)量矩陣Amass的逆矩陣。ThiscreatesanaccelerationmatrixAspring.Aspringistheinverseofthecondensedmassmatrix,Amass.NOTE:Aspring=a11加速度矩陣等于彈簧加速度矩陣乘以