Q/SZJ191001-2017控制臂疲勞疲勞分析規(guī)范Specificationofanalysisforcontrolarmfatigue20XX20XX-XX-XX實(shí)施20XX-XX-XX發(fā)布XXXX汽車工程技術(shù)有限公司發(fā)布Q/SZXX-X-2017控制臂疲勞分析規(guī)范范圍本標(biāo)準(zhǔn)規(guī)定了術(shù)語和定義、控制臂疲勞分析方法及結(jié)果處理方法。本標(biāo)準(zhǔn)適用于CAE部門控制臂疲勞分析。規(guī)范性引用文件無。術(shù)語和定義本規(guī)范涉及到的術(shù)語及其定義如下：控制臂（ControlArm）連接副車架和轉(zhuǎn)向節(jié)的底盤零部件。摘要Abstract本流程根據(jù)應(yīng)變-壽命理論描述了控制臂裂紋萌生疲勞分析方法。Thisproceduredescribescrackinitiationfatigueanalysisaccordingtothestrain-lifeconceptforcontrolarm.疲勞分析的目的是識(shí)別因重復(fù)或變化的載荷而導(dǎo)致的危險(xiǎn)區(qū)域，而這些載荷遠(yuǎn)未達(dá)到一次就可導(dǎo)致結(jié)構(gòu)發(fā)生破壞的程度。Thepurposeofanyfatigueanalysisistoidentifycriticalareasduetorepeatedorotherwisevaryingloading,whichneverreachesalevelhighenoughtocausefailureinasingleoccurance.對(duì)于控制臂疲勞分析而言，是由線彈性應(yīng)力分析，循環(huán)材料，交變載荷以及損傷模型等組成。Forcontrolarmsfatigueanalysisiscomposedofalinearelasticstressanalysis,cyclicmaterialconsideration,varyingloadingapplicationandthedamage-modellingpart.在有限元分析中，在載荷作用點(diǎn)施加單位載荷。隨后將每個(gè)單位載荷下的應(yīng)力分布與對(duì)應(yīng)的載荷歷程相組合。這種組合的結(jié)果就是交變載荷作用在部件上的應(yīng)力歷程。最后通過線性疊加得到每個(gè)單元的載荷歷程。Inthefiniteelementanalysisunitloadsareappliedtoloadapplicationpoints.Subsequently,thestressdistributionforeverysingleunitloadinputiscombinedwiththecorrespondingtimehistoryofloading.Theresultsofthisfactorizationareasmanystresshistoriesasvaryingloadsactingonthecomponent.Finally,alinearsuperpositionisperformedfromwhichoneloadinghistoryperfiniteelementisobtained.應(yīng)力歷程和循環(huán)載荷作用下的材料響應(yīng)描述輸入到實(shí)際的疲勞分析當(dāng)中。Togetherwithadescriptionofthematerialresponsetocyclicloading,thesecombinedstresshistoriesareinputtotheactualfatigueanalysis.疲勞分析軟件會(huì)進(jìn)行彈塑性轉(zhuǎn)換。載荷歷程最終會(huì)被提取成等效的常幅循環(huán)載荷。使用Palmgren-Miner累積損傷假設(shè)，開展疲勞壽命預(yù)測(cè)分析并給出施加載荷的重復(fù)循環(huán)次數(shù)信息。Thefatigueanalyzercodecarriesoutelastic-plastictransformations.Thesequencesoftheloadinghistoriesareextractedassetsofequivalentconstantamplitudecycles.UsingthePalmgren-Minersummationdamagehypothesis,fatiguelifepredictioniscarriedoutwhichgivesinformationabouttherepeatabilityoftheappliedhistories.流程圖ProcessFlowDiagram準(zhǔn)備準(zhǔn)備強(qiáng)度分析輸入Gatherinputforstrengthanalysis目標(biāo)達(dá)成？TargetReached?準(zhǔn)備模型Preparatoryworkonmodel準(zhǔn)備材料Preparatoryworkonmaterial準(zhǔn)備載荷PreparatoryworkonloadingDocumentandreport運(yùn)行疲勞分析RunfatigueanalysisObtainfiniteelementinputfile.Inquireaboutmaterialandloadinghistories.獲取有限元輸入文件，查詢材料和載荷歷程曲線。

Editinputfileforfatigueanalysis.Ifnecessary,refinemesh.Carryoutalinearelasticstressfiniteelementanalysis.編輯疲勞分析輸入文件，如有必要優(yōu)化網(wǎng)格。開展線彈性有限元靜力學(xué)分析。Lookforappropriatecyclicmaterialinformationandentermaterialpropertiesintomaterialdatabase.查找恰當(dāng)?shù)难h(huán)材料信息并將材料屬性輸入到材料數(shù)據(jù)庫中。

Checktheloadinghistoriesintermsofsamplingrate,noise,spikesetc.Importhistoriesintoloadingdatabase.檢查載荷歷程的采樣頻率，噪聲，尖峰值。將載荷歷程導(dǎo)入到載荷數(shù)據(jù)庫中。Importmodelwithfiniteelementresultsofunitloadcasescalculation.Associatethefiniteelementloadswiththeirtimevariations.導(dǎo)入單位載荷有限元結(jié)果模型。將載荷歷程與有限元計(jì)算結(jié)果相關(guān)聯(lián)。Selectstrain-lifefatigueanalysis.UseSmith-Watson-Toppermeanstresscorrection.SelectNeuberplasticitycorrection.Activateabiaxialitycheck.Performfatigueanalysisonelementsusingaveragingformaximumabsoluteprincipals。選擇應(yīng)變-壽命疲勞分析，使用Smith-Watson-Topper平均應(yīng)力修正。選擇Neuber塑性修正，激活二軸率檢查。使用單元平均絕對(duì)值最大主應(yīng)力開展疲勞分析。

Checkdamagemodelatthecriticalareas.Modifymodel,ifnecessary.檢查模型危險(xiǎn)區(qū)域的損傷值。如有必要，修改模型。

Reportonanalysis.Documentwithdamagecontourplot.編寫報(bào)告，記錄損傷云圖。

NOYES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(shí)間(Time) 秒(Second)內(nèi)容Contents疲勞分析模型與結(jié)構(gòu)靜力學(xué)分析并無差異。Thefatiguemodeldoesnotdifferfromthestructureanalysismodel.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根據(jù)材料的循環(huán)應(yīng)力-應(yīng)變曲線和壽命-應(yīng)變壽命曲線，建立應(yīng)變-壽命理論開展裂紋萌生疲勞分析。Crackinitiationfatigueanalysisaccordingtothestrain-lifeconceptbuildsuponthecyclicstress-straincurveandthestrain-lifecurve.另外需要考慮的材料信息是抗拉強(qiáng)度（UTS）和屈服強(qiáng)度（Ys）。Additionalmaterialinformationtakenintoaccountistheultimatetensilestrength(UTS)andtheyieldstress(Ys).值得注意的是材料循環(huán)屬性高度依賴于表面加工質(zhì)量和后處理。Beawarethatcyclicmaterialpropertiesarehighlydependentonfactorssuchassurfacetreatmentandfinish.假設(shè)和限制Assumptions/Limitations假設(shè)Assumptions就應(yīng)力計(jì)算而言：Asfarasstresscalculationsareconcerned:習(xí)慣性使用線彈性理論（NASTRANSOL101求解器）；Customaryassumptionsofthelineartheoryofelasticityareused(NASTRANSol101);材料的性能是在室溫下測(cè)定的。Materialperformanceistestedatroomtemperature限制Limitations疲勞天生就是隨機(jī)的：載荷歷程受駕駛員、路面和天氣條件影響，材料屬性受制造工藝的影響，仿真分析受模型的影響等。Bynature,fatigueisstochastic:loadinghistoriesareinfluencedbydriver,roadandweatherconditions,materialpropertiesareinfluencedbythemanufacturingprocess,simulationisinfluencedbythemodellingetc.載荷和邊界條件Loads/BoundaryConditions邊界條件BoundaryConditions對(duì)于試驗(yàn)場(chǎng)載荷仿真，使用慣性釋放方法。對(duì)于臺(tái)架測(cè)試試驗(yàn)仿真，邊界條件和測(cè)試規(guī)范相同。Forprovinggroundsimulationinertiareliefisperformed.Fortestrigsimulationtheboundaryconditionsareaccordingthetestspecification.載荷Loads試驗(yàn)場(chǎng)仿真分析，控制臂上需加載9個(gè)作用力。Whenperformingaprovinggroundsimulation9singleforcesactonthecontrolarm.圖2控制臂載荷示意圖Figure2Loadsatcontrolarm力Fx，F(xiàn)y，F(xiàn)z作用在ForcesFx,Fy,andFzapplyat?球鉸theballjoint(Fbjt)?副車架前安裝點(diǎn)thefrontsubframemount(Fsmf)?副車架后安裝點(diǎn)therearsubframemount(Fsmr)性能要求PerformanceRequirements控制臂扭轉(zhuǎn)疲勞的壽命應(yīng)不小于1200次循環(huán)。Thelifeofcontrolarmfatigueshouldnotlessthan12,00repeats.在疲勞分析的后處理中確定結(jié)構(gòu)的壽命。對(duì)于0.1%失效概率的估算壽命為：N=Ncal*DM*Tm(-1/2)其中：Ncal：50%存活率下的計(jì)算壽命DM：Miner常量Tm：制造分散性Youmightascertaintheservicelifewithinthepost-processingofthefatigueanalysis.Theestimatedservicelifefor0.1%probabilityoffailureis:N=Ncal*DM*Tm(-1/2)with:Ncal:calculatedservicelifefor50%probabilityofsurvivalPSDM:Miner’sconstant.Tm:manufacturingscatter使用Miner常量DM考慮分析方法的系統(tǒng)誤差。DM的典型值為0.4?？紤]制造分散性Tm，典型值為3~5。UsetheMiner’sconstantDMtotakeintoaccountsystematicerrorsofthemethod.AtypicalvalueforDMis0.4forcasts.TakeintoconsiderationthescatterofmanufacturingTm.TypicalvaluesofTmarebetween3and5.分析要求ANALYSISREQUIREMENTS對(duì)于控制臂的疲勞分析，推薦使用殼單元絕對(duì)值最大主應(yīng)力。Themaximumabsoluteprincipalelementstressesarerecommendedforfatigueanalysisonthesolidcontrolarmswithshellskins.選擇最保守的Smith-Watson-Topper平均應(yīng)力修正方法。使用Neuber塑性修正將局部彈性應(yīng)變轉(zhuǎn)換成局部彈塑性應(yīng)變。SelectSmith-Watson-Toppermeanstresscorrectionmethodwhichisgenerallythemostconservativemethod.Inordertotranslatefromthelocalelasticstraintothelocalelastic-plasticstrain,useNeuber’splasticitycorrection.激活二軸比檢查評(píng)估使用方法的正確性。Activateabiaxialitychecktoassessthevalidityoftheusedapproach.檢查是否為單軸加載，其為疲勞分析的隱含假設(shè)。Checkifuniaxialityisgiven,asthisassumptionisimplicitforthedescribedfatigueanalysis.單軸加載是指在交變載荷作用下，只有結(jié)構(gòu)響應(yīng)的應(yīng)力幅發(fā)生，而應(yīng)力的方向不變。這種情況