NVH座椅建模规范

Q/SZJ191001-2017NVH座椅建模规范SpecificationofNVHModelingforseats20XX20XX-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-2017NVH座椅建模规范范围本标准规定了术语和定义、NVH座椅建模方法及结果处理方法。本标准适用于CAE部门的NVH座椅建模。规范性引用文件无。术语和定义无。摘要Abstract商用车的座椅是一个复杂的结构和非结构的复杂装配。座椅是为驾乘者提供舒适和安全的基本部件。市面上不同车型的座椅大小不一,形状各异。重要的是获得可靠的座椅模型，用于车辆的NVH性能评估，用于怠速抖动,光滑路面的性能评定抖动和粗糙的路面振动条件。本文件中将讨论座椅装配的建模准则,供系统NVH分析。由于座椅装配模型的复杂性和程序固定,最好的近似方法只能在特定的条件下定义。Aseatinacommercialvehicleisacomplicatedassemblyofstructuralandnon-structuralcomponents.Seatsareessentialcomponentsprovidingcomfortandsafetyfortheoccupants.Therearevarioussizeandshapesofseatsfordifferentvehiclesonthemarket.ItisimportanttoobtainareliableseatmodelforvehicleNVHperformanceassessmentforidleshake,smoothroadshakeandroughroadshakeconditions.ThemodelingguidelinesofseatassemblyaretobediscussedinthisdocumentforsystemNVHanalysis.Duetothecomplicatednatureoftheseatassemblymodelandprogramtiming,abestapproximationmethodcanonlybedefinedwithcertaingivenconditions.、

流程图ProcessFlowDiagram图1图1流程图Fig1ProcessFlowDiagram座椅CAD模型seat-in-whiteCADmodel建立简化模型BuildSimpleModel建立详细模型BuildSimpleModel模态计算SubmittoNastranorOptistruct模型配重CheckModelMass模型输出ModelCheckout: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或OptiStruct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有限元的模型内容包括结构特征，有几何和材料属性，内饰质量，以及地板与座椅导轨连接的边界条件。Thecontentsofthefiniteelementmodelshouldincludeastructuralrepresentation,composedof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。Analysisusevehicleglobalcoordinatesystem,andlocalcoordinatesystemsareneededforsomespringsinthetrimmedbody.建模技巧ModelingTechniques商用车的座椅是一个复杂的结构和非结构的装配。座椅包括靠背和坐垫，可以按照以下不同的方式：·简化座椅模型-总质量/惯性矩和/或座椅刚度。·详细座椅模型-一个详细的板/壳单元模型金属结的座椅构造，梁用于模拟金属丝和泡沫/座椅盖，其他内饰件用集中质量。当详细模型参数不完整不可用时，建议使用简化的座椅模型，为特别研究或座椅设计验证时，一个详细的座椅模型是被推荐的。基于测试座椅的频率传递功能,从座椅轨道/底板到驾驶员座椅底部和座椅靠背位置，可以处理为一些粗糙的道路平顺性度量评估或优化。座椅背部和底部传递的准确性仍然取决于座椅轨道响应的可靠性。座椅对地板的动态效果影响非常重要,单凭单向传递函数可能无法表示此效果。简化建模技巧由于时间或缺乏验证设计无法提供详细座椅模型，简化座椅模型，有三个简化模型的常用类型：·简化模型的软连接：通过RBE3连接，采用集中质量（conm2）与地板进行连接。将质量/惯量分布到与地板连接位置上。座椅质量用集中质量单元（conm2）模拟，于CG代表其质量、惯量模拟。可通过座椅台架的摆动试验或估算得到。集中质量单元通过RBE3与地板进行连接固定。图2简化座椅软连接Fig2SimplifiedSoftSeat·座椅质量用集中质量单元（conm2）模拟，集中质量单元通过RBE2用弹簧单元(CELAS2)与地板进行连接固定。座椅是用集中质量单元conm2表示质量和转动惯量，可以通过硬件或摆动试验得到的估计模型。集中质量单元通过刚性单元RBE2与地板进行连接，约束自由度123，集中质量单元CONM2依附于刚性单元RBE2的主点。座椅与地板之间的连接可以通过弹簧单元CELAS2进行连接.假设在每个方向上的所有连接位置都有相等的刚度，这些弹簧单元的刚度值被调整为近似值。图3列出驾驶员座椅与地板4个连接处。由于该模型是线性分析，通过平动自由度来调整弹簧刚度，所以同螺栓、钩销之间与地板连接没有区别。图3简化座椅模型与地板的4个连接Fig3(SimplifiedTunedSeatwith4FloorConnections注:集中质量单元conm2和惯性特性可以单独代表座椅总成，或座椅和乘员，取决于分析的类型（模态分析或道路响应/怠速抖动分析）。相关的模态验证，正常的模态测试车辆是没有乘员的。然而，PSD路谱采集时必须包括驾驶员。·集中的质量/惯量，调整座椅靠背的刚度(调整座椅靠背角度)-两个集中质量单元通过弹簧单元（CELAS2）模拟两端座椅靠背刚度。整个座椅质量/转动惯量被分为一个在座椅底部CG(m1)和另一个在座椅靠背CG（M2），如图4.3.1-3所示。M1的连接建模与简化的软座椅连接相似。座椅靠背和座椅底座用H型铰链进行连接。M1上通过6个自由度全约束的刚性单元RBE2连接到H型铰链上。M2也是通过6个自由度全约束的刚性单元RBE2连接到H型铰链。图4简化座椅靠背模型Fig4SimplifiedTunedSeatBackModel有一对重合的单元连接H型铰链，Y向转动DOF5控制座椅靠背的前后转动，X向转动DOF4来调节座椅靠背的横向运动。转动弹簧刚度(K4和K5)可以分别调整，分别调节横向和前后运动模式，以匹配实验测试或早期车辆开发计划。详细的建模技术座椅轨道与地板有各种不同的连接方式。通常座椅有限元模型由座椅供应商建立。座椅模型要适用于噪声和振动分析的系统模型。详细的座椅模型实例图5图5简化座椅靠背模型Fig5(SimplifiedTunedSeatBackModel座椅总成一般可分为两部分:座椅骨架(SIW)和座椅附件。座椅骨架（SIW）采用壳，梁单元，和弹簧单元进行详细建模。座椅用集中质量单元或非结构质量单元建模。一个集中质量单元通过RBE3分布一个区域内，有多少RBE3和集中质量相连接取决于座椅类型，在图6中显示了一个相对详细的座椅内饰质量的例子。分析人员应该验证座椅模型是否设计合理，质量/惯性，质心，以及是否与一些适当的测试数据相吻合。图6驾驶员座椅的质量分布例子Fig6AnExampleofTrimmedMassDistributionforaDriver’sSeatAssemblyAseatinacommercialvehicleisacomplicatedassemblyofstructuralandnon-structuralcomponents.Seats,includingbucketseatsandbenchseats,canbemodeledinthefollowingdifferentways:·Simplifiedseatmodel–lumpedmass/momentofinertiaand/orseatstiffnessareused.·Detailedseatmodel-adetailedplate/shellelementmodelfortheseatmetalstructures,beamelementsformetalwires,andlumpedmassforfoams/seatcoversandothertrimmeditems.Asimplifiedseatmodelisrecommendedwhenavalidateddetailedmodelisnotavailable.Forspecialstudyorseatdesignvalidation,adetailedseatmodelisrecommended.Notethatatestbasedseatfrequencytransferfunctionsfromseattrack/floortodriverseatbottomandseatbacklocationscanbetreatedasapost-processforsomeroughroadridemetricevaluationoroptimization.Theaccuracyoftheresponsesontheseatbackandthebottomstilldependsonthereliabilityoftheseattrackresponses.Theseatdynamiceffectonthefloorisveryimportant,andtheone-waytransferfunctionsalonemaynotbeabletorepresentthiseffect.SimplifiedModelingTechniqueDuetotimingorlackofvalidateddesignintentdetailedseatmodels,simplifiedseatmodelsareusuallyapplied,Therearethreecommontypesofsimplifiedmodels:·Lumpedmass/inertiawithnostiffness(SoftSeat)-ACONM2forthewholeseatwithRBE3todistributethemass/inertiatotheconnectingfloorlocations.TheseatismodeledusingoneCONM2elementlocatedatitsCGtorepresentitsmassandinertiathatcanbeobtainedbyswingtestoftheseathardwareorestimate.RBE3elementsareusedtoconnecttheCONM2elementtothefloorattachmentlocations.·Lumpedmass/inertiawithtunedstiffness(TunedSeat)–ACONM2forthewholeseatwithRBE2spidertoitsfloorlocationsandconnectingtothefloorwithspring(CELAS2)elements.TheseatismodeledusingoneCONM2elementlocatedatitsCGtorepresentitsmassandmomentsofinertia.Coincidentgridsarecreatedattheseat-floorconnectionlocations.RBE2elementsareusedtoconnecttheCONM2elementtothesecoincidentgridsintheDOF123.TheCONM2elementshouldbeplacedattheindependentgridoftheRBE2elements.OnlyDOF123areneededfortheRBE2spiderconnections.TheCONM2shouldbelocatedattheindependentgridofthespider.TheconnectionsbetweenthecoincidentgridsandtheflooraremadebytheCELAS2springelements.Assumingequalstiffnessratesatalltheseattachmentlocationsineachdirectionrespectively,thestiffnessvaluesofthesespringelementsaretunedtoapproximatethelateral,verticalandfore/aftmodesoftheseatbasedonavailabletestdataforroughroadvibrationsimulation.Figure4.3.1-2showsanexampleofdriverseatwith4connectionlocationsatthebodyfloor.SincethemodelisusedinalinearanalysisandonlyDOF123(translationalDOF)areconsideredinthetunedspringstiffness,nodistinctionismadebetweenabolt-onandahook-pinconnectionatthefloor.NOTE:ThemassandinertiapropertiesoftheCONM2canrepresenttheseatassemblyalone,ortheseatassemblyandoccupant,dependingonthetypeofanalysisbeingdone(i.e.,normalmodesanalysisorroadresponse/idleshakeanalysis).Thereasonisthatwhencorrelatingtomodaltests,anormalmodeslaboratorytestisdonewithnooccupantinthevehicle.However,aPSDroadresponsemeasurementmustincludethedriver.·Lumpedmass/inertiawithtunedseatbackstiffness(TunedSeatBack)–TwoCONM2elementsandtwoseatbackstiffnessrateswithspring(CELAS2)elements.Thewholeseatmass/momentofinertiaisdividedintooneattheseatbottomCG(m1)andintoanotheroneattheseatbackCG(m2)asshowninFigure4.3.1-3.Theconnectionmodelingofm1issimilartothatofthesimplifiedsoftseat.TheJointHisdefinedasthehingelocationbetweentheseatbackandtheseatbottom.Thegridatm1isconnectedtothejointHusingRBE2withall6-DOFs.ThejointHisconnectedtogridatm2byaRBE2withall6-DOFs.ThereisapairofcoincidentgridsforthejointHthatcanonlyrotateintheDOF5forseatbackfore/aftandDOF4forseatbacklateralmotions.Therotationalspringstiffnessrates(K4andK5)canbetunedrespectivelytomatchthelateralandfore/aftvibrationmodesoftheseatbackfromalabtestorfromaspecificationinaearliervehicleprogram.DetailedModelingTechniqueTherearevarioustypesofseatstructuresandseattrack-to-floorconnections.Thedetailedseatmodelsinfiniteelementsarenormallybuiltbyseatsuppliers.BothSMTandSystemmodelsfornoiseandvibrationanalysesapplythereceivedseatmodels.SomeoftheexamplesofthedetailedseatmodelsareshowninFigures5.Componentsoftheseatassemblycanbegenerallydividedintotwogroups:seat-in-white(SIW)andseattrim.ASIWismodeledindetailusingshell,beam,andspringelementsasstated.SeattrimismodeledusingeitherCONM2ornon-structuralmassasstatedinthisdocument.ThelumpedmassofaCONM2isdistributedoveranareabyRBE3spider.HowmanyRBE3spidersandwheretoconnectthemdependsontheseattypeandtherelativesignificanceofthelumpedmass.ArelativedetailedexampleofmodelingtheseattrimmedmassisshowninFigure6.Thesystemanalystshouldverifythattheseatmodelrepresentstherightdesignlevel,themass/momentofinertia,centerofmass,andifithasbeencorrelatedtosomeappropriatetestdata.假设和限制Assumptions/Limitations在给定的条件下，座椅模型的动力学性能是线性的。Thedynamicsperformanceoftheseatmodelsislinearforagivenoperatingconditio