内饰车身噪声传递函数分析规范

Q/SZJ191001-2017内饰车身噪声传递函数分析规范SpecificationOfNoiseTransferFunctionAnalysisAnalysisForTrimmedBody20XX20XX-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内饰车身噪声传递分析规范范围本标准规定了术语和定义、内饰车身噪声传递分析方法及结果处理方法。本标准适用于CAE部门的内饰车身噪声传递分析。规范性引用文件无。术语和定义无。摘要Abstract噪声传递函数分析主要考察声传递特性，是对车身与底盘之间的主要连接区域进行声学传递函数分析，以便找出噪声传递路径及对NVH特性影响较大的关键零部件。对车身与动力系统及底盘系统接附点施加单位载荷，分析计算乘员耳侧的噪声响应。本规范旨在描述噪声传递函数的分析方法、要求和评价标准。NTFanalysisismainlyfocusedonacoustictransmissioncharacteristics,andtakesacoustictransferfunctionanalysistoidentifynoisetransferpathsandkeypartsofalargerinfluenceontheNVHcharacteristics.Imposetheunitloadontheattachmentpointsbetweenthebodyandpowertrain,chassissystem,thengetthenoiseresponsebesidesthedrivers’earandpassengers’ear.Thisspecificationspecifiesthemethods,requirementsandEvaluationstandardfortheanalysisofthenoisetransferfunction.

流程图ProcessFlowDiagram收集详细模型收集详细模型(TrimmedBody)CollectDetailedModels(TrimmedBody)设置边界条件和载荷SettheboundaryConstraintsandLoads提交计算NastranSOL111RunNastranSOL111结果后处理（HyperGraph）Resultsprocessing（HyperGraph）输出X向位移（声压）OutputXDisplacements(Soundpressure)结束End优化Optimization结果是否满足要求？IstheresultOK？YesNo评价标准Evaluationstandard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噪声传递函数分析主要考察结构在外激励作用下乘员舱驾驶员处的噪声响应水平，外激励频域为2Hz-200Hz。NTFanalysisdetectsthenoiseresponseatthedriver’sseatinthepassengercompartment,onwhichapplytheexternalunitloadvariedwiththefrequencyinthe20Hz-200Hzdomain.噪声传递函数分析模型分为结构有限元模型和声学空腔有限元模型，两种模型耦合在一起。其中结构有限元模型是带内饰的TrimmedBody模型（以下简称TB模型），TB模型按照是否带副车架又分为不带副车架的TB模型和带副车架的TB模型两种。ThemodelusedintheanalysisofnoisetransferfunctionincludeFEMmodelandfiniteelementmodelofacousticcavitymodels,andthesetwoarecoupledtogether.StructurefiniteelementmodelsistheTrimmed-Bodymodelswithinteriorbody(hereinafterreferredtoasTBmodel).theTBmodelcanbedividedintotwokinds,onewithasub-frameandtheotherwithoutasub-frame.副车架与车身的连接是软连接通过衬套连接的，使用不带副车架的TB模型进行NTF分析。图2是不带副车架的NTF分析有限元模型。Onthesituationtheconnectionbetweenthesub-frameandthebodyissoft,useTBmodelwithoutasub-frametodoNTFanalysis.Thefiniteelementmodelwithoutasub-frameusedinNTFanalysisisshowinfigure2.图2不带副车架的NTF有限元模型Fig2ThefiniteelementmodelwithoutsubframeinNTF车架与车身连接是硬连接通过螺栓连接的，使用带副车架的TB模型进行VTF分析。图3是带副车架的VTF分析有限元模型。Whenthesubframeandbodyisconnectedbythehardbolts,VTFanalysisusesaTBmodelwithsub-frame.Figure3showsafiniteelementmodelwithsub-frameinVTFanalysis.图3带前后副车架的NTF有限元模型Fig3Thefiniteelementmodelwithfrontandrearsub-framesinNTF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,Localcoordinatesystemsareneededforsomespringsinthetrimmedbody.建模技巧ModelingTechniques请参阅TrimmedBodyRefertotheTrimmedBodymodelingguidelines.接附点的衬套直接用螺栓与车身侧连接时，需要建立一维CBEAM或CBAR单元螺栓模型，如摆臂接附点，见图4所示。加载点在CBEAM或CBAR单元的中点。Onthesituationthebushismodeledasaboltconnectedtothebody,a1DCBEAMelementorCBARelementcanbeusedtomodelthebolt.Forinstance,anattachmentpointattheswingarmisshowedinFigure4.TheloadingpointisatthemiddlelocationofCBEAMorCBAR.图4衬套直接用螺栓与车身侧连接的建模示意图Fig4Bushingasabolt接附点的衬套以支架总成形式与车身侧连接时，需要将固定衬套橡胶的钢圈用RBE2单元连接，钢圈中心点为RBE2主节点，钢圈上节点为RBE2从节点，RBE2单元耦合全部6个自由度。加载点在RBE2主节点，如发动左悬置接附点见图5所示。Onthecircumstancethemountingpointbushispresentedbyabracketassemblyconnectedtothebodyside,aRBE2elementshouldbeusedtomodeltherimsonthefixedbushingrubber.Theindependentnodeisthecenterofrim,andtheindependentnodesconnectthewholerim.TheRBE2coupledall6degreesoffreedoms.TheloadisimposedontheindependentnodeofRBE2.Forinstance,theleftenginemountpointisasshowninFig5.图5发动机左悬置接附点建模示意图Fig5Theleftenginemountmodeling如图6所示，为前、后减振弹簧安装支座处接附点建模方式，其加载点为前后减振弹簧支座中心点。ThemodelingmethodoffrontandreardampingspringinstallationsupportsisshowedinFigure6.Theloadingpointisthecenterpointofsprings.图6前、后减振弹簧接附点建模示意图Fig6frontandreardampingSpringsmodeling车身侧排气系统接附点的建模方式为，将被动侧挂钩与挂钩隔振器相连的区域的节点用RBE2单元与从节点连接，主节点自动生成，RBE2单元耦合全部6个自由度。加载点在RBE2单元的主节点。图7是车身侧排气系统接附点的建模示意图。Bodysideexhaustsystemmodelingmethod：TheRBE2isusedtomodelthemountingpoint,withitsdependentnodesconnectingthenodesontheregionwhichrelatedthepassivelinktothelinkisolator,whileitsindependentnodeisautomaticallygenerated.TheRBE2couplesall6degreesoffreedom.Itsindependentnodeistheloadingpoint.Figure7showsthebody-sideexhaustsystemmodeling.图7车身侧排气系统接附点建模示意图Fig7Thebody-sideexhaustsystemmodeling假设和限制Assumptions/Limitations无。载荷和边界条件Loads/BoundaryConditions约束：自由模态。Noconstraints.包括底盘悬架系统与车身相连的接附点、发动机与车身相连的接附点、副车架与车身相连的接附点、排气与车身相连的接附点。不同车型间可能因为底盘悬架系统、发动机安装方式、副车架连接和排气系统的不同，而存在差异。图8为接附点位置示意图，其中副车架、前悬、后摆臂、后减振器、后弹簧安装点、排气吊挂安装点。Includeschassissystemandvehiclebodyattachmentpoints,engineandbodyattachmentpoints,sub-frameandbodyattachmentpoints,exhaustandbodyattachmentpoints.Betweendifferentmodelsbecausethechassissuspensionsystems,engineinstallation,connectedtotheframeandexhaustsystemsofdifferent,therearedifferences.Figure8-mountpoints,subframe,frontsuspension,rearswingarm,rearshockabsorbers,rearspringmountingpoint,exhaustsuspensionattachmentpoints.图8接附点位置示意图Fig8mountpoints加载：在接附点处分别沿XYZ三个方向，加载1N随频率（2Hz~200Hz）变化的动载荷。ApplyunitloadsattheattachmentpointsinX,YandZdirectionsontheseparatesubcases.andfrequencyfrom2Hzto200Hz;加载方向和接附点的受力方向一致。接附点受力方向如果与整车坐标不一致，需要根据受力方向建立局部坐标，如摆臂接附点。图9是局部坐标、整车坐标示意图。Applytheloadintheattachmentpointsforceddirection.Iftheloadingdirectionisinconsistentwiththeglobalcoordinatesystem,thelocalcoordinatesystemisneeded.anattachmentpointattheswingarmisshowedinFigure8.Figure8showsthelocalandglobalcoordinatesystems.图9局部坐标、整车坐标示意图Fig9Thelocalcoordinatesystemandtheglobalcoordinatesystem载荷大小：单位载荷1N。Load:unitload1N模态阻尼：1-20Hz是0.1，20－400Hz是0.04；Modaldamping:1-20Hzwas0.1,20-400Hzwas0.04;载荷激励频率范围：2Hz－200Hz；Loadexcitationfrequencyrange:20Hz－200Hz；结构模态频率范围：0Hz－400Hz；Structuralmodalfrequencyrange:0Hz－400Hz声腔模态频率范围：0Hz－600Hz；Acousticmodefrequencyrange:0Hz－600Hz；求解采用NASTRAN模态频率响应SOL111。Solve111声固耦合用NASTRAN语句ACMODL来控制。表1是NTF分析中ACMODL卡片参数，参数具体含义参考NASTRAN手册。Acoustic-structuralcoupletakestheNASTRANstatementsACMODLtobecontrolled.Table1showstheACMODLcardparametersusedintheNTFanalysis,andthespecificmeaningofparametersreferstotheNASTRANmanual.表1NTF分析中ACMODL卡片参数ACMODLDIFFGRIDS1.BW0.50.750.5NOREL具体的参数设置详见13例子Specificparametersettingsisshowninchapter13EXAMPLES.结果Results输出驾驶员外耳、副驾驶员以及后排乘员内外耳声压（即位移）Outputtheearpressure(displacement)insideandoutsideofthedriver,co-pilotandcrewintheback.图10输出点位置示意图Fig10outputpointslocation输出XYZ三个方向响应曲线，曲线是输出点的声压级响应曲线。输出曲线X轴表示频率，单位为Hz，Y轴为响应的声压级，单位为dB。输出结果的响应频率是20Hz－200Hz。图11是右前摆臂后点NTF响应曲线示意图。图11NTF响应曲线示意图Fig11NTFresponsecurveTheoutputcurveisthesoundpressurelevelresponsecurve.TheXaxisoftheoutputcurverepresentsthefrequency,andtheunitisHz.TheYaxisrepresentssoundpressureresponse,theunitisdB.Theresponsefrequencyrangeoftheoutputis20Hz-200Hz.Figure11istheNTFresponsecurveofarightfrontarm.车内结构噪声是车身噪声传递函数与激励力的乘积，降低车身噪声传递函数是降低车内噪声的有效方法之一。车身噪声传递函数用表示，单位是dB,参考声压是。………….（1）代表车身结构的振动传递函数，代表车身振动转化为测量点处的噪声能力。把测量点的空气压力转化为声压级………..（2）参考声压=参考声压为28.28e-12，peak为20.0e-12Bodystructurenoiseistheproductofthenoisetransferfunctionandtheexcitationforce.Reducingvehiclenoisetransferfunctionisoneofthemosteffectivewaystoreduceinteriornoise.BodynoisetransferfunctioncanberepresentedbyP/F,andtheunitisdB，referencesoundpressureis.………….（1）Representsbodystructurevibrationtransferfunction，Representstheperformancethatthebodyvibrationsconvertstothenoiseofthemeasurementpoints.Converttheairpressuretothesound-pressurelevelofthemeasuringpoint.………..（2）referencesoundpressure=referencesoundpressureis28.28e-12，peakis20.0e-12性能要求PerformanceRequirements分析得到的结果曲线是噪声传递函数的声压级响应曲线，响应曲线与目标值进行比较，如果分析得到的响应曲线结果小于目标值，则满足NTF分析的要求；响应结果曲线如果有高于目标值曲线的，则不满足NTF分析要求。Theresults-curveisthesoundpressure-levelcurveofthenoisetransferfunction.Comparethecurvewiththetargetcurve.TheresultmeetstherequirementsofNTFanalysisifitislessthanthetargetvalue.Itisfailedwhenthecurveishigherthanthetargetvaluecurve.通用目标值，排气挂钩≤60dB，其它接附点≤55dB。Thegeneraltarget:exhaustlinkedpoint<=60dB,otherpoints<=55dB.针对不同车型定位不同，目标值可根据具体项目要求进行调整。Thetargetvaluecanbeadjustedaccordingtothespecificprojectrequirements.分析要求ANALYSISREQUIREMENTS参考文件DOCUMENTATION无。联系人CONTACTS无。例子EXAMPLESSOL111$=======================================================================$CASECONTROLSECTION$AUTOSPC(NOPRINT)=YESECHO=NONEMETHOD(STRUCTURE)=10METHOD(FLUID)=20FREQ=30SDAMPING=40$$$$$$$$$$$$$$NodeSETforOutputaboveAllSubcases.SET99=9001$$DISPLACEMENT(PLOT)=99$$SUBCASE1SUBTITLE=FLTOPMTGXDLOAD=1$SUBCASE2SUBTITLE=FLTOPMTGYDLOAD=2$SUBCASE3SUBTITLE=FLTOPMTGZDLOAD=3$$$=======================================================================BEGINBULK$$PARAMPOST-1PARAMCOUPMASS1$PARAM LFREQ2.0PARAMGFL0.16PARAM ACOUT RMS$PARAM,CHECKOUT,YESACMODLDIFFGRIDS1.BW0.50.750.5NOREL$==============================================================================$RLOAD110011000150DLOAD11.01.01001DAREA10001101011.0DLOAD21.01.01002RLOAD110021000250DAREA10002101