Q/SZJ191001-2017結構聲學分析規(guī)范StructuralAcousticAnalysis20XX20XX-12-31實施20XX-11-27發(fā)布XXXX汽車工程技術有限公司發(fā)布Q/SZXX-X-2017結構聲學分析規(guī)范范圍本標準規(guī)定了術語和定義、結構聲學分析方法及結果處理方法。本標準適用于CAE部門的結構聲學分析。規(guī)范性引用文件無。術語和定義無。摘要Abstract結構聲學分析能夠分析出車廂內的噪聲水平,由于車輛結構板件的振動，如道路、動力總成或儀器的輸入載荷等激發(fā)出振動產生噪聲。有限元方法已成功地應用于此類分析。這種類型的模擬涉及到車輛結構和內部空氣(聲學)的空腔有限元建模,并把結構聲腔和流體聲腔耦合在一起。車輛早期設計階段，聲學性能的改進是昂貴和費時的，通過有限元分析可以有效的解決這一問題，早期解決潛在的問題和風險，快速有效的提高了車輛的NVH性能。本程序論述了結構聲學分析程序和計算環(huán)境，這篇文檔討論的程序是應用在卡車上的做法，這里討論的程序具體指的是目前在卡車上的做法。本程序還討論了有限元用nastran進行耦合的方法。結構聲學分析主要針對低頻結構噪聲20-200Hz范圍進行分析和優(yōu)化降噪（范圍可根據模型搭建的詳細程度而定），結構聲學分析可以提供以下。?車身聲學靈敏度定義為內部聲壓施加到車身的力，產生的振動稱為噪聲傳遞函數即聲壓/激勵力(P/F)。?由于路面、動力總成和傳動系統(tǒng)產生的振動源，通過車架和底盤連接件傳遞到車身，再引起車身板件振動，從而產生噪聲。?車身面板的動態(tài)特性決定了噪音峰值。?車身板件的模態(tài)特性也決定了噪音峰值。結構聲學分析要建立結構有限元模型（白車身或內飾車身、底盤和動力系統(tǒng)總成）和內部聲學腔模型，對兩個模態(tài)模型進行耦合，進行結構聲學板件貢獻量分析。通過對板件貢獻量分析結果可以找出引起振動噪聲的結構偏弱區(qū)域，從而對該結構進行更改，能在設計初期快速的解決潛在的結構弱點。Structuralacousticanalysispredictsthenoiselevelinsidethepassengercompartmentduetovibrationofvehiclestructuralpanelsexcitedbyloadssuchasroad,powertrain,orinstrumentedinputload.Thefiniteelement(FE)approachhasbeensuccessfullyappliedforsuchanalyses.Simulationofthistypeinvolvesfiniteelementmodelingofboththevehiclestructureandtheinteriorair(acoustic)cavityandcouplingthestructuralvibrationofbodypanelswithpressureloadingonthecavitywalls.Detailedhardwarechangesforimprovedvehicleacousticsandevaluationoftheireffectivenessattheprototypestagecanbecostlyandtimeconsuming.Thisproblemcanbeveryeffectivelyaddressedbyusingnumericalacousticmodelingattheearlydesignphases.ApplicationofsuchanalyseshasledtoimprovedNVHperformanceofvehiclesthroughearlyrecognitionandcorrectionofpotentialproblems.Thisprocedurediscussesthestructuralacoustic(S/A)analysisproceduredevelopedatGeneralMotorsandenhancementstoadapttothecurrentcomputingenvironment.TheprocedurediscussedherespecificallyreferstothecurrentpracticeatTruck.thisprocedurealsodiscussestheapproachapplyingNASTRANS/Acouplingschemes.TheFES/Asolutionstrategycanbeextremelyusefulforpredictinglowfrequencyinteriorstructure-bornenoiseinthe20-200Hzrange(Therangemayvarybasedonthelevelofdetailsinthemodel)andforexploringdesignchangestoreducetheboomsoundinvehicles.Inparticular,structuralacousticanalysiscanprovide:?Bodyacousticsensitivity,definedasinteriorsoundpressureduetounitforceappliedtothebody.ThisquantityisalsoreferredtoasthenoisetransferfunctionorP/F(pressure/force).?Structure-borneinteriornoiseinthefullvehiclesystemduetoroadinputsorpowertrainanddrivelinedisturbancestransmittedtothebodythroughframeandbodymounts.?Panelparticipationfactorsthatquantifydynamiccontributionofaspecificbodypanelareatoaparticularnoisepeak.Thegeneralapproachtostructuralacousticanalysisistocreatemodalmodelsofthevehiclestructure(body-onlyorbody,chassisandpowertraincombined)andtheinterioracousticcavityfromFEmodels;couplethetwomodalmodelsandthensolvethecoupledsystemmodelforacousticpressure[Ref.3].Theanalystcanalsorecovervariousmodalinformationofboththestructureandcavitytoidentifypotentialstructuralweaknesscontributingtonoiseandthenstudytheacousticeffectsofstructuralmodification.Onceagivenmodeliscorrelated,anydesignchangestudiescanbemadewithinaveryshortturnaroundtime.

流程圖ProcessFlowDiagram收集詳細模型(內飾車身和聲腔模型)CollectDetailedModels(TrimmedBodyandAcousticCavity)收集詳細模型(內飾車身和聲腔模型)CollectDetailedModels(TrimmedBodyandAcousticCavity)結構聲學相關分析StructuralAcousticCorrelationAnalysis設置邊界條件和載荷SettheboundaryConstraintsandLoads結果后處理（HyperWorks）Resultsprocessing（HyperWorks）結束End結果是否滿足要求？IstheresultOK？優(yōu)化OptimizationNo評價標準EvaluationstandardYes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或OptiStruct后處理(Postprocessors):Hyperview建模和分析過程Modeling/AnalysisProcedure所有的模型必須符合NVH建模標準，以及符合噪聲和振動分析的建模文檔。AllmodelsmustconformtotheNVHmodelingstandardsasoutlinedaswellastheindividualcomponentmodelingdocumentsasapprovedbytheNoiseandVibrationFocusGroup.單位Units分析中所用單位制如下所示:Theunitsusedintheanalysisareasfollows:力(Force) 牛頓(N)質量(Mass) 噸(Ton)長度(Length) 毫米(mm)時間(Time) 秒(Second)內容Contents坐標系CoordinateSystems分析采用整車坐標系。Analysisusevehicleglobalcoordinatesystem.建模技巧ModelingTechniques無。假設和限制Assumptions/Limitations無。載荷和邊界條件Loads/BoundaryConditions載荷：自由模態(tài)分析，沒有載荷。約束：無AsthisisaFree-Freemodalanalysis,noloadsarerequiredforanalysis.Load:N/A結果Results聲腔固有頻率CavityNaturalFrequency本節(jié)討論乘員艙的聲腔分析，在用NASTRAN計算前要做充足的準備工作，NASTRAN流體材料使用MAT10。表1是常規(guī)的模態(tài)分析，調用求解器SOL103，聲腔分析只有一個自由度。Thissectiondiscussestheanalysisoftheaircavityofthepassengercompartment.BeforeexecutingtheNASTRANrunoftheaircavitymodel,certainpreparationsmustbemade.TheproceduredescribedusestheMAT9cardapproach(NASTRAN3-DAcousticModelingUsingStructuralAnalogy,Ref.4)fordefiningairphysicalproperties.SeeTable4.4.1-1belowforasampleNASTRANdeckoftheaircavitynormalmodesrun.ItisaregularNASTRANSOL103runexceptanSPCshouldbeusedtoreleaseoneDOFforacousticpressure.表1聲腔模態(tài)分析IDJJ,MODAL_CAVITY$SOL103TIME6000CEND$TITLE=GMT360ACOUSTICCAVITYMODELSUBTITLE=p/FCALCULATIONSLABEL=SEATSRETAINED$MAXLINES=100000ECHO=SORT(PARAM,EIGRL,FORCE,MOMENT,SPC,SPCADD,PSHELL,MAT1)$METHOD=1DISP(PLOT)=ALL$BEGINBULK$PARAM,POST,-1PARAM,COUPMASS,1PARAM,GRDPNT,1$$EIGENVALUEEXTRACTIONCARDEIGRL,1,,150.0$INSERTACOUSTICCAVITYMODELBULKDATAHERE..ENDDATA后處理PostProcessing。在NASTRAN計算之后，需要對模態(tài)位移云圖進行評估。對聲壓變化的輪廓線進行定義，以確定聲壓的模態(tài)振型。如圖2是一階縱向聲腔模態(tài)。圖2一階縱向聲腔模態(tài)Fig2Contourplotofthefirstcavitymode下面是聲壓求解和后處理過程:a)運行nastran求解器,獲取HyperView結果文件。b)同時使用模型文件和結構文件，在HyperView中打開聲壓云圖(聲壓變化圖)。c)聲壓即是位移，查看X向位移。d)查看聲壓云圖。第一個模態(tài)是一個小于0Hz的剛體模態(tài)。剛體模態(tài)的聲壓云圖是同一顏色。SubsequenttotheNASTRANrun,modeshapesoftheaircavityneedtobeevaluated.Contourplotsofsoundpressurevariationmustbeevaluatedtodeterminethemodeshape.SeeFigure4.4.1.1-1foranexampleofafirstfore/aftcavitymodecontourplot.Belowistherecommendedprocedurefordisplayingsoundpressurevariationcontourplots:a)FromtheNASTRANrun,converttoaHyperViewresultsfile.b)Createfringeplots(soundpressurevariation)inHyperViewusingthecavitymodelandtheresultsfile.c)ForX-DOF,useX-displacement(analogyofacousticpressure).d)Evaluatecontoursplotstodeterminemodeshapes.Thefirstmodeisarigidbodymodeoccurringat0Hz.Thecolorcontourfortherigidbodymodeshouldbeonecolor.相關性Correlation分析工程師需要將聲腔模態(tài)與實驗結果進行對標。聲腔的模態(tài)可以通過調整座椅質量密度來調節(jié)座椅容積。通常情況下,測試結果可能會與仿真分析結果有幾赫茲的差異。Theanalystneedstocorrelatethecavitymodalfrequencywithexperimentalresults.Themodalfrequencyofthecavitymodescanbeadjustedbytuningtheseatequivalentmassdensityforseatvolume.Normallythetestresultsmayvaryseveralhertzforcavitymodefrequencies.手工計算HandCalculations聲腔模型分為多個諧振腔，對模型要進行檢查。分析人員需要對nastran結果與手工計算的模態(tài)結果進行比較。參考聲學空腔的建模過程，討論了對聲腔的手工計算。計算公式如下：Cavitymodescanbeestimatedasstatedinthemodelcheckingsectionofthecavitymodel.TheanalystsshouldalwayscomparetheNASTRANresultswiththehandcalculationofmodalfrequencies.Refertotheacousticcavitymodelingprocedureforthediscussionofthehandcalculationofthecavitymodes.圖3理論計算公式Fig3Theoreticalformula下面是一些例子用于指定i,j,k:Belowaresomeexamplesforspecifyingi,jandk:1stFore/AftMode=>i=1,j=0,k=02ndFore/AftMode=>i=2,j=0,k=01stLateralMode=>i=0,j=1,k=0下面的例子根據理論公式計算空腔振動頻率BelowaresomeexamplesforcalculatingestimatedcavityresonantfrequenciesfortheM-Van:Lx=3.67m1stFore/AftMode,F(1,0,0)=47.3HzLy=1.64m1stLateralMode,F(0,1,0)=105.8HzLz=1.18m1stVerticalMode,F(0,0,1)=147.0Hz試驗Experimental測試數據從NVC獲得，頻率范圍為0-250Hz之間，NVC可以使用揚聲器作為乘員艙內的激勵裝置來獲得聲腔的一階固有模態(tài)，麥克風在乘員艙內漫游測量車廂的聲壓級水平，測量精度會有偏差，但其他聲腔聲壓很難測量?？梢允褂美碚摴竭M行手動計算。對于卡車，一階聲腔模態(tài)可能是橫向或者縱向，這取決于駕駛室設計的相對尺寸。TestdataistobeobtainedfromNVC.Afrequencyrangebetween0and250Hz(with.25Hzresolution)isrecommended.NVCcandeterminethefirstfundamentalmodeofthecavitybyusingspeakersastheexcitationdeviceinsidethepassengercompartment.Microphonesareroamedinsidethepassengercompartmenttoapproximatelydeterminethefieldofsoundpressurelevel.Thetestcavitymodemayhavecertainvariationsduetothemeasurementmethodsused.Determinationofothercavitymodesisdifficulttoachieve.Thehandcalculationtechniquecanbeusedforpreliminarycorrelation.Typically,the1stcavitymodeistheF/Amodeformostofthevehicle.Forpick-uptruckcabs,the1stcavitymodecouldbelateralorverticaldependingontherelativedimensionsofcabdesign.性能要求PerformanceRequirements參考文件DOCUMENTATION無。聯系人CONTACTS無。例子EXAMPLES相關分析CorrelationAnalysis第一步：結構模態(tài)(StructuralNormalModes)此步驟將生成車身模態(tài)結果文件OP2。ThisstepgeneratesthebodymodelOP2file.表2：$***************************************************************************$NASTRANCASECONTROLFORSTEP#1FORGMRSTRUCTURAL-ACOUSTICANALYSIS:::$NAS1SDECKFORNASTRAN$*************************************************************************NastranSparse=25NASTRANSYSTEM(151)=1$IDJJ,STEP1TIME1000000SOL103CEND$METHOD=1DISP(PLOT)=ALL$BEGINBULK$INSERPARAMCARDSHEREPARAM,POST,-1..$SIDFminFmaxNDMsgLvlMaxSetSHFSCLEIGRL10.150.0$$INSERTNASTRANBULKDATAofBODYMODEL(NOTE:DONOTUSEINCLUDESTATEMENT)..ENDDATA第二步：聲腔模態(tài)(AcousticNormalModes)此步驟將生成聲腔模態(tài)結果文件OP2。ThisstepgeneratesthecavityOP2file.第三步：結構模型和聲腔模型流固耦合(AcousticNormalModes)這一步產生結構和流體耦合矩陣。Thisstepgeneratesthecouplingmatricesandcoupledstructure/fluidgrids.表3:$BOUNDARYDATADECKFORACOUSTICCOUPLING:::STEP#3$CONTROLTEMPLATEFORVECLOADIDJJ,STATICSOL101TIME30$RFALTERSTOOUTPUTEQEXIN,BGPDTANDPGZDATABLOCKSINCLUDEsssalterdir:RF101D002CEND$TITLE=VECLOADGENERATIONSUBTITLE=CAVITYSKIN$OLOAD=ALL$$LOADINGONFRTFLOORSUBCASE1LOAD=1001$……$LOADINGONREST(MISC)SUBCASE15LOAD=1015BEGINBULK$$PLOADCARDSFORSKIN$$INSERTNASTRANBULKDATAofCAVITYSKINMODELandPLOADCARDFOREACHPANEL$MAKESURETHENORMALVECTORSARECONSISTENTFORALLTHEPANELS$(NOTE:DONOTUSEINCLUDESTATEMENT)……ENDDATA表4：$NASSTFILEforNASTRAN$IDSTRGRID,GENERATIONSOL103TIME9999$INCLUDEsssalterdir:RF103D002..CEND$METHOD=1$BEGINBULK$INSERTPARAMCARDSHERE..$EIGRL10.0150.0$$INSERTNASTRANBULKDATAofBODYMODEL(NOTE:DONOTUSEINCLUDESTATEMENT)..ENDDATA表5：$STRUCTURAL_ACOUSTIC:STEP#3$IDRESPONSE,MODALTIME6000DIAG14SOL111$**********************************************************$$RFALTERFORMODAL&PANELPARTICIPATIONANALYSIS$$**********************************************************$INCLUDEsssalterdir:RF111D504CEND$========================================================TITLE=ACOURESP$MPC=2SPC=1METHOD=1FREQUENCY=100DLOAD=509$K2PP=STIFM2PP=MASS$SET10=300589OUTPUTDISP(PLOT,PHASE)=10$OUTPUT(XYPLOT)XYPUNCHDISPRESPONSE/300589(T3RM,T3IP)BEGINBULK$Sinceonlytheacousticresponsegrids&thestructurally-coupled$acousticgridsareintheAcousticCavity"modal"model,NASTRAN$willissue"WARNINGMSG2051A,UNDEFINEDGRIDPOINTINSPCSET"SPC1112456300001THRU303174$EIGRL1150.0$MPCADD,2,1,400000,500000FREQ1,100,20.0,0.50,240$RLOAD2,501,601,,,310..RLOAD2,512,612,,,310TABLED1,310,+,0.,1.,200.,1.,ENDT$UNITSINUSOIDALINPUT(VERTICAL)DAREA,601,100021,3,1.0..DAREA,612,100016,3,1.0$ENDDATA表6:'ANALYSISMODEL''Alpha3a''FULL''STRUCTUREDATA'1099870802295135'CAVITYDATA'3074203'VEHICLESYSTEMDATA'20.000.50100.00140.00'DAMPINGCOEFFICIENTS'.040.060'GRIDOFFSETS'000000000000000000000000'SURFACEDATA'130.0'SPOINTOFFSETS'1400000500000400000500000'INTERIORGRIDS'3300589302776300951'ATTACHEDGRIDS'1410000206…'FREQUENCIES''COMP1S'2150.000140.0002150.0180.0200.0210.0220.0230.024..138.010138.266138.754138.944139.588'FREQUENCIES''COMP2S'80.000140.00080.00050.53193.21997.015108.298116.869135.655136.864'COUPLEDSTRUCTURALGRIDS'105180610541701064179101408010679501051652105173210529371063918..'COUPLEDACOUSTICGRIDS'300100300107300136300271300273300330300331300343300383第四步：創(chuàng)建模態(tài)模型(ComponentModalModelGeneration)這一步創(chuàng)建了結構和聲學腔模態(tài)模型。ThisstepcreatesGETMODEfiles(modalrepresentation)ofthestructuralbodyandacousticcavity.第五步：聲學響應分析(AcousticResponseAnalysis)結構和聲學腔耦合模型，用于測試車輛的聲壓級水平。案例分析是測量車輛路面、動力總成及其他激勵源引起的振動、噪聲和瞬態(tài)響應。TheanalystcannowcouplethebodyandcavityGETMODEfilewithsurface.coup.dmitopredicttheacousticresponseofsub-systemorvehiclelevel.Thetemplatefilestoanalyzevehiclenoiseduetoroad,powertrainandimpactloadshouldrefertothechaptersforroadresponse,powertraininducedvibration/noise,andtransientresponse.表7:IDRESPONSE,MODALTIME6000SOL111$RFALTERFORMODAL&PANELPARTICIPATIONANALYSIS$$UncommentthefollowinglinetoperformModalandPanelParticipationAnalysis$INCLUDEsssalterdir:RF111D504CENDTITLE=FORCEDACOUSTICRESPONSE(BODYACOUSTICSENSITIVITY)$USEdifferentSUBCASEnumberfordifferentLOADINGLOCATION$Thistemplateshowedonly1LOADCASEMPC=1SPC=2FREQUENCY=200DLOAD=500METHOD=1K2PP=STIFM2PP=MASSOUTPUTSET1=600497,601285,602045$GRID600497:PASSENGER'SEAR(FRONTSEAT)DISP(PHASE)=1OUTPUT(XYPLOT)XYPLOT,XYPUNCHDISPRESPONSE/600497(T3RM,T3IP)BEGINBULK$Sinceonlytheacousticresponsegrids&thestructurally-coupled$acousticgridsareintheAcousticCavity"modal"model,NASTRAN$willissue"WARNINGMSG2051A,UNDEFINEDGRIDPOINTINSPCSET"SPC1212600001THRU602512EIGRL1150.0MPCADD1300000400000$FREQ1,200,20.,1.,130$RLOAD2,500,600,,,310TABLED1,310,+,0.,1.,150.,1.,ENDT$UNITSINUSOIDALINPUT(VERTICAL)$BodyMountGrid229721DAREA,600,229721,3,1.$$followingINCLUDEincludebodyandcavitymodaldatabase(GETMODEfile)INCLUDE'/db/pzcldt/workingdir/comp1s.mod.out'INCLUDE'/db/pzcldt/workingdir/comp2s.mod.out'$followingINCLUDEincludestheStructural-AcousticcouplingmatricesINCLUDE'/db/pzcldt/workingdir/surface.coup.dmi'ENDDATA第六步：板件貢獻量分析(AcousticResponseAnalysis)表8:SOL111TIME9