Q/SZJ191001-2017NVH模型相關(guān)性分析規(guī)范SpecificationofCorrelationofNVHModels20XX20XX-12-31實(shí)施20XX-11-27發(fā)布XXXX汽車工程技術(shù)有限公司發(fā)布Q/SZXX-X-2017NVH模型相關(guān)性分析規(guī)范范圍本標(biāo)準(zhǔn)規(guī)定了NVH模型相關(guān)性分析的方法。本標(biāo)準(zhǔn)適用于CAE部門NVH模型相關(guān)性分析。規(guī)范性引用文件無。術(shù)語和定義無。摘要Abstract測(cè)試與分析之間相關(guān)性分析就是比較并減少兩者之間差異的迭代過程，從而達(dá)到滿意的效果。這個(gè)過程是分析中非常重要和不可分割的一部分，尤其對(duì)于整車分析來說。在產(chǎn)品開發(fā)中引入一種新分析方法時(shí)，都應(yīng)該進(jìn)行模型相關(guān)性分析。新分析方法產(chǎn)生的結(jié)果在被接受前必須與測(cè)量結(jié)果進(jìn)行對(duì)標(biāo)，同時(shí)分析時(shí)輸入了不確定的參數(shù)時(shí)，也要進(jìn)行相關(guān)性分析。Testandanalysiscorrelationisdefinedasaniterativeprocessofidentifyingandreducingthedifferencesbetweentestmeasurementsandtheanalyticalsimulationofanobjecttoasatisfactorylevel.Itisanimportantandintegralpartoftheanalysisprocess,especiallyforafullvehiclesystemanalysis.Thecorrelationshouldbeperformedwhenanewanalysismethodologyisunderdevelopment.Theresultsofthenewmethodshouldbevalidatedagainsttestresultsbeforeitcanbeacceptedasananalysistoolforvehicledesign/developmentsupport.Additionally,correlationshouldbeperformedwhenananalysismodelhasinputparameterswhichareunreliableordifficulttoquantify.流程圖DesignReleaseDesignRelease設(shè)計(jì)數(shù)據(jù)發(fā)布BOMVariation明細(xì)改變ManufacturingVariation加工工藝改變AssemblyVariation裝配工藝改變TheoryAssumptions理論假設(shè)ModelingApproximations模型近似ModelingError模型錯(cuò)誤TestAcquisition獲取測(cè)試結(jié)果DataProcessing數(shù)據(jù)處理AnalysisLimitations分析局限Boundary/LoadConditions邊界/加載Model=Hardware?模型與實(shí)物是否一致Correlation?修正結(jié)果是否正確。NO否Yes是Yes是End完成Yes是NO否圖1流程圖工具描述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無。坐標(biāo)系CoordinateSystems無。建模技巧ModelingTechniques無。假設(shè)和限制Assumptions/Limitations無。載荷和邊界條件Loads/BoundaryConditions無。結(jié)果Results結(jié)果格式ResultsFormats無。相關(guān)測(cè)試CorrelationTests在處理測(cè)試結(jié)果與分析結(jié)果之間的差異時(shí)，就需要進(jìn)行相關(guān)性分析。如流程圖所示，有很多因素會(huì)導(dǎo)致這兩者之間的差異。預(yù)先假定測(cè)試對(duì)象和分析模型都是針對(duì)同一設(shè)計(jì)，盡管在現(xiàn)實(shí)中是很難達(dá)到的。測(cè)試與分析在兩個(gè)不同路徑上每個(gè)階段都會(huì)引入誤差從而導(dǎo)致最終結(jié)果不同。Theneedforcorrelationarisesfromthefactthattherearealwayssomephysicaldifferencesbetweenwhatistestedusinghardwareandwhatissimulatedusingamodelonsupposedlythesameobject.Asshowninprocessflowdiagramchart,therearemanyfactorscontributingtothedifferencesbetweenfullvehicletestdataandvehiclesystemmodelsimulationresults.Assumethetesthardwareandanalysismodelsharethesamereleaseddesigns,whichdoesnotalwayshappenintherealworld.Theytraveltwototallydifferentroutestowardtheirfinalresultsandeachstageintroducesmorevariations/errors.測(cè)試Hardware/Test明細(xì)表差異：由于設(shè)計(jì)誤差導(dǎo)致的差異。如：鈑金的料厚會(huì)有+0.4mm的誤差；供應(yīng)商提供的車身安裝點(diǎn)剛度或者懸架襯套剛度值一般會(huì)有±20%的誤差。制造差異：零件幾何尺寸、厚度和其它設(shè)計(jì)名義值在制造過程中都會(huì)產(chǎn)生偏差。如排氣管的直徑在折彎后會(huì)從設(shè)計(jì)值的63mm變成實(shí)際的59mm，同時(shí)折彎處厚度也會(huì)變小。裝配差異：丟失焊點(diǎn)。由于不同的安裝扭矩導(dǎo)致車身安裝點(diǎn)預(yù)緊力不一致。頂蓋粘膠不一致。數(shù)據(jù)獲?。狠斎牒洼敵鳇c(diǎn)的安裝位置誤差（通常會(huì)有±1.0英寸）。不同測(cè)量?jī)x器，如在路面上進(jìn)行測(cè)試時(shí)，由于測(cè)試人員、測(cè)試時(shí)間、天氣條件（溫度、風(fēng)、路面濕滑）和起點(diǎn)/終點(diǎn)等不同，都會(huì)導(dǎo)致不同測(cè)試結(jié)果。另外一個(gè)差異來源是測(cè)試過程中頻率處理。在測(cè)試中，頻率結(jié)果是離散分布的。要確保測(cè)試工程師使用頻域結(jié)果，這樣可以比較清楚對(duì)比測(cè)試與分析之間的差異。數(shù)據(jù)處理：要隨時(shí)牢記在測(cè)試結(jié)果中模態(tài)振型的處理算是一個(gè)比較主觀的過程。不同的工程師可能曲線擬合測(cè)試數(shù)據(jù)的方式不同，這會(huì)導(dǎo)致模態(tài)頻率和振型的少許差異。BillofMaterialsvariation:materialsvariationsduetodesigntolerance.Forexample,steelsheetmetalthicknessmayhaveatoleranceof+0.4mm.Thestiffnessofabodymountorasuspensionbushingprovidedbyasupplieristypicallyanominalvalue±20%.Manufacturingvariation:Deviationofapart’sgeometry,thickness,andotherattributesfromthedesignednominalvaluesduringmanufacturingprocess.Thediameterofanexhaustpipeatthebendmaybe59mminsteadofthedesigned63mm.Itsthicknessatthebendmayalsobesmaller.Assemblyvariation:Missingspotwelds.Inconsistentbodymountpre-loadduetoinconsistenttorque.Inconsistentgumdropsbetweentheroofouterpanelandtheroofbow.Dataacquisition:Approximategeometrycoordinatesforinput/outputpoints(typicallytapemeasured.±1.-incherror).Variationinthecalibrationofinstruments.Forvehicleon-roadmeasurements,inconsistencyofresultsmaybecausedbydifferenttestpersonnel,testingdata,weatherconditions(temperature,wind,dry/wetroadsurface),andstar/endlocation.Anothersourceofvariationisfrequencyresolutionoftesting.Intest,frequencyresultsareobtainedatdiscretepoints.Makesurethatthetestengineerusesafrequencyresolutionthatwillallowforaclearcomparisonoftestandanalysisresults.Dataprocessing:Keepinmindthattheprocessofobtainingmodeshapesfromtestingissometimesasubjectiveprocess.Differentengineersmaypossiblycurvefitthetestdatadifferentlythuscreatingslightlydifferentmodefrequenciesandshapes.建模與分析Modeling/Analysis理論假設(shè)：變形較小，材料在線彈性區(qū)間內(nèi)。在分析結(jié)構(gòu)聲腔噪聲時(shí)，排除了空氣噪聲的影響（如風(fēng)燥、排氣噪聲、發(fā)動(dòng)機(jī)噪聲或輪胎噪聲），實(shí)際在路面測(cè)試中是存在的。模型近似：阻尼模擬不精確。忽略了內(nèi)飾板的剛度、阻尼和吸聲/反射。忽略了除焊點(diǎn)連接外的接觸。彈性模擬由于頻率、預(yù)緊、溫度和大變形的原因，并不準(zhǔn)確。對(duì)于大多數(shù)底盤件（如主軸、支架等）進(jìn)行剛體處理。建模誤差：人為誤差和建模規(guī)范差異，特別是大而復(fù)雜的模型。如焊點(diǎn)缺失、單元質(zhì)量、不恰當(dāng)?shù)膯卧叽?、零件缺失、質(zhì)量缺失。分析限制：在模態(tài)頻率響應(yīng)分析中的模態(tài)截?cái)?。在路面激?lì)中無側(cè)向和前后向。無輪胎與路面相互作用（如輪胎顛簸）邊界條件與加載：不正確或不合適的邊界條件與加載：加載位置與方向；自由模態(tài)測(cè)試中未考慮氣囊影響；未考慮SPC約束時(shí)實(shí)際存在彈性。Theoreticalassumptions:Deformationissmall;materialbehavesinthelinearelasticrange.Simulationsonstructurebornenoiseonlywithnoconsiderationofair-bornenoiseadditionssuchaswindnoise,exhaustnoise,powertrainnoiseortirenoise,whichalwaysexistwhenrecordedduringroadtest.Modelingapproximation:Inaccuratesimulationofadampingmechanism.Ignoranceofstiffness,dampingandacousticabsorption/reflectionbyinteriortrimpanels.Nocontactbetweentwopartsexceptattheweldlocations.Elastomersimulationnotabletoaccountforitsassumptionformostchassismetalpartssuchasspindle,bracketsandetc.Modelingerror:Mostlyhumanerrorandviolationofmodelingguidelines,especiallyforalargeorcomplicatedmodel.Examplesare:missingwelds,badelementquality,inappropriatemeshsize,missingparts,missingmasses.Analysislimitation:Modaltruncationerrorformodalfrequencyresponseanalysis.Nolateralorfore/aftdirectioninroadinput.Notire/roadinteractionsuchastireenvelopingbump.Boundary/loadingcondition:Incorrect/inappropriatesimulationoftestboundaryorloadingconditionssuchas:inaccuratelocationororientationofload.Notcountingtheeffectofairbagsupportforfree-freemodal.IgnoranceoftestfixtureflexibilitywhenSPCisused.數(shù)據(jù)對(duì)比ComparisonofData測(cè)試條件與車輛配置：在對(duì)比測(cè)試結(jié)果與分析結(jié)果時(shí)，必須清楚地列出測(cè)試條件與車輛配置信息，其它如：胎壓、油箱燃油量、載重、環(huán)境溫度、路面濕滑、邊界條件（彈性繩、氣囊、其它固定）等。質(zhì)量：測(cè)試中的質(zhì)量（如有可能，盡量包括質(zhì)量分布和轉(zhuǎn)動(dòng)慣量）與分析中的質(zhì)量進(jìn)行對(duì)比，兩者之間的差異應(yīng)在5%以內(nèi)。模態(tài)：在模態(tài)測(cè)試總列出模態(tài)頻率和模態(tài)振型描述。應(yīng)為模態(tài)振興描述非常主觀，所以必須得到UNV格式的測(cè)試數(shù)據(jù)，以便于在后處理軟件與分析結(jié)果對(duì)比變形動(dòng)畫、MAC和COMAC值。通常，頻率之間差異在10%以內(nèi)，振型MAC值大于0.75才能接受。頻率響應(yīng)函數(shù)（簡(jiǎn)稱FRF）：此處是指加速度、速度、位移、力、聲壓或其它在頻域的響應(yīng)輸出，而輸入是指正弦波、粗糙路面功率譜、或沖擊塊撞擊等。對(duì)比測(cè)量與分析的FRF數(shù)據(jù)比較復(fù)雜，因?yàn)槭且粭l連續(xù)的曲線，而不是一個(gè)值。現(xiàn)在還沒有明確的標(biāo)準(zhǔn)來判斷兩者之間相關(guān)性的好壞。每個(gè)模型相關(guān)性分析分析團(tuán)隊(duì)都要明確自己的判斷標(biāo)準(zhǔn)來滿足項(xiàng)目要求。下列問題在評(píng)判時(shí)經(jīng)常被問到的，按照重要性排序：趨勢(shì)、峰值數(shù)量級(jí)、峰值頻率、峰值幅值、曲線下面積、曲線間面積。根本原因研究：當(dāng)測(cè)量與分析之間相關(guān)性分析效果不佳時(shí)，就要進(jìn)行根本原因研究。在沒有理解其差異的根源，就直接修改分析模型以匹配測(cè)試是不恰當(dāng)?shù)?。很多因素?huì)導(dǎo)致差異，見流程圖所示，應(yīng)當(dāng)一步步進(jìn)行篩選排查。在結(jié)果相差太大時(shí)一個(gè)主要根源是建模錯(cuò)誤，見流程所示。回顧每個(gè)建模步驟是否安裝建模規(guī)范來是非常有幫助的。當(dāng)進(jìn)行模態(tài)頻率和模態(tài)振型相關(guān)性分析時(shí)，應(yīng)變能分析可以發(fā)現(xiàn)高應(yīng)變能分布的子系統(tǒng)或零件。通常研究應(yīng)變能分布可以判斷其分布是否合理，從而修改此區(qū)域的結(jié)構(gòu)來改變模態(tài)振型或頻率。當(dāng)進(jìn)行FRF曲線峰值頻率或幅值對(duì)比時(shí)，模態(tài)貢獻(xiàn)量分析可以幫助發(fā)現(xiàn)那些模態(tài)對(duì)峰值貢獻(xiàn)大。同樣，針對(duì)這些貢獻(xiàn)量大的模態(tài)優(yōu)化，可以改變相應(yīng)的峰值頻率或幅值。TestCondition/VehicleContents:Testconditionsandvehiclecontentsshouldbeclearlystatedwhencomparingtestandanalysisresults,whichincludebutarenotlimitedto:tirepressure,fueltanklevel,payload/ballast,ambienttemperature,dry/wetpavement,boundaryconditions(bungeecord,airbag,orotherfixtures),etc.Mass:Themass(ifpossible,massdistributionandmassmomentofinertia)ofthetesthardwareshouldbeobtainedandcomparedtothoseoftheanalysismodel.Thedifferenceshouldbewithin5%.NormalModes:Atablecontainingnormalmodefrequenciesandmodalshapedescriptionsaretypicaloutputsfromamodaltest.Becausemodeshapedescriptionsarehighlysubjective,itisnecessarytoobtainanelectroniccopyofmodaltestresultsintheuniversalfileformat,whichcanbeinputtopost-processingsoftwareandcomparedagainstanalyticalmodelresultsthroughvisualanimation,MACandCOMACcalculations.Forthosemodesdeemedimportant,afrequencydifferencewithin10%andmodalshapeMACvaluesgreaterthan0.75areconsideredgoodcorrelation.FrequencyResponseFunctions:Frequencyresponsefunctions(FRF’s)usedinitsmostgenericformhere,referstoacceleration,velocity,displacement,force,acousticpressure,orotherresponseinthefrequencydomainduetovarioustypesofloadssuchassinusoidalinput,roughroadPSDinput,orimpactbumpinput.ThecomparisonofFRF’sbetweentestandanalysisismorecomplexbecauseitininvolvesacontinuouscurveinsteadofasinglevalue.Thereisnoclearlydefinedstandardonwhetherthecorrelationisgoodornot.Eachcorrelationteamshouldsetupitsownacceptancecriterionstoservetheobjectiveoftheproject.Discussedbelowareseveralfrequentlyusedrulestojudgethelevelofcorrelationandpairsofexamplesasillustrations,intheorderimportance:Trend,PeakRanking,Peakfrequency,PeakAmplitude,AreaundertheCurve,Areabetweenthecurves.RootCauseStudy:Whenthecorrelationbetweenthetestandanalysisresultsisnotsatisfactoryarootcausedstudyshouldbeconductedtofindoutwhatcausedthedifference.Itisnotagoodpracticetoblatantlymakemodificationstotheanalysismodelsothatitsresultswouldmatchthoseofthetestwithoutunderstandingwhatreallycausedthepoorcorrelation.Whencorrelatingnormalmodefrequencyandmodeshape,astrainenergycalculationfromtheanalysismodelisgoodtooltoidentifywhichsub-system/parthasthehighpercentageofstrainenergy.Usuallybystudyingthesehighpercentageareas,onecandecidewhetherthespecificmodeisreasonableornot,andchangethemodalshapeorfrequencybymodifyingthestructureinthoseareas.WhencorrelatingapeakfrequencyoramplitudeforaFRFcurve,modalparticipationfactorscanbeusedtoidentifywhichmodeormodescontributemosttothepeakresponse.Inturn,byfocusingonthesemodes,onemaybeabletovarythepeakfrequencyoramplitudeasdesired.整車模型相關(guān)性分析VehicleSystemModelCorrelation整車模態(tài)：為了得到好的整車模態(tài)相關(guān)性，必須首先進(jìn)行子系統(tǒng)模態(tài)的模型相關(guān)性分析。車體模態(tài)：對(duì)于內(nèi)飾車身，自由模態(tài)的模型相關(guān)性分析是必須的。如果資源和時(shí)間許可，白車身的自由模態(tài)模型相關(guān)性分析要首先進(jìn)行。在模態(tài)測(cè)試時(shí)，內(nèi)飾車身或白車身通常是使用幾個(gè)氣囊懸掛支撐來模擬自由邊界狀態(tài)。因?yàn)闅饽也⒉皇墙^對(duì)的“軟”，其剛體模態(tài)通常在1Hz到5Hz之間，而不是0Hz。所有六個(gè)剛體模態(tài)測(cè)量時(shí)必須確保：1)剛體模態(tài)與第一階彈性模態(tài)之間分離徹底；2)可以用來提升模型相關(guān)性分析效果。這些氣囊可以使用CELAS單元來模擬三個(gè)方向的剛度。調(diào)整剛度值來匹配測(cè)試結(jié)果。由于內(nèi)飾車身處理的數(shù)據(jù)量大，則自由模態(tài)的模型相關(guān)性分析分析通常在30Hz以下，并僅對(duì)幾個(gè)主要模態(tài)，如：整體彎曲/扭轉(zhuǎn)/側(cè)向模態(tài)、前端側(cè)向/垂向模態(tài)、頂蓋/地板呼吸模態(tài)、座椅側(cè)向/前后模態(tài)。對(duì)于聲腔，通常在30Hz以下。車架模態(tài)：對(duì)于車架自由模態(tài)，模型相關(guān)性分析是必要的。車架要包括前后碰撞梁總成，而備胎和油箱是可選的。在模態(tài)測(cè)試中，車架通常使用幾個(gè)氣囊懸掛支撐來模擬自由邊界狀態(tài)。這些氣囊在分析中可以通過CELAS單元來模擬平動(dòng)剛度。剛度值可以調(diào)整以匹配測(cè)試中的六個(gè)剛體模態(tài)。通常在30Hz以下，針對(duì)幾個(gè)主要模態(tài)如一階和二階垂向彎曲、側(cè)向彎曲、扭轉(zhuǎn)、側(cè)向模態(tài)進(jìn)行模型相關(guān)性分析。懸架模態(tài)：懸架模型相關(guān)性分析主要針對(duì)測(cè)試中的跳動(dòng)HOP和走步TRAMP模態(tài)。懸架模態(tài)測(cè)試還沒有統(tǒng)一的標(biāo)準(zhǔn)。一般在整車在順滑路面以10到15公里/小時(shí)速度通過一個(gè)AES沖擊塊。走步TRAMP模態(tài)在只有一側(cè)輪胎通過沖擊塊時(shí)被激發(fā)，而跳動(dòng)TOP模態(tài)在兩側(cè)輪胎通過時(shí)被激發(fā)。需要測(cè)試四個(gè)輪主軸的加速度響應(yīng)。在整車中，可以使用模態(tài)或瞬態(tài)響應(yīng)分析來提前跳動(dòng)TOP/走步TRAMP模態(tài)。另外，在測(cè)試中，四通道臺(tái)架來激勵(lì)懸架以提取跳動(dòng)TOP/走步TRAMP模態(tài)數(shù)據(jù)。由于輪胎沒有滾動(dòng)，必須小心提取臺(tái)架中的數(shù)據(jù)。在測(cè)試懸架的TOP/走步TRAMP模態(tài)時(shí)，按照以前的經(jīng)驗(yàn)，滾動(dòng)輪胎的剛度要小于不滾動(dòng)輪胎。這意味著在四通臺(tái)架測(cè)試的模態(tài)頻率要稍微高于路面滾動(dòng)狀態(tài)下的值。排氣系統(tǒng)模態(tài)：排氣系統(tǒng)模型相關(guān)性分析過程就是一個(gè)懸臂梁的模態(tài)分析。排氣系統(tǒng)下行管和掛鉤應(yīng)接地約束。如果沒有約束條件，則應(yīng)安裝在整車上進(jìn)行測(cè)試。每種條件下的分析與測(cè)試相對(duì)應(yīng)。進(jìn)行50Hz以下模態(tài)的模型相關(guān)性分析?？梢哉{(diào)節(jié)掛鉤來匹配排氣系統(tǒng)的第一階懸臂梁的側(cè)向和彎曲模態(tài)。注意排氣管的形狀、直徑和料厚，因?yàn)檫@些在制造過程中可能與設(shè)計(jì)值不符了。貨車車箱模態(tài)：在實(shí)驗(yàn)室中進(jìn)行車箱的自由模態(tài)模型相關(guān)性分析。車箱通常使用彈性繩或氣囊懸掛來提供自由邊界條件。在分析中可以通過CELAS單元來模擬平動(dòng)剛度。剛度值可以調(diào)整以匹配測(cè)試中的六個(gè)剛體模態(tài)。如果可能，可以對(duì)沒有背門的車箱再進(jìn)行測(cè)試，以研究背門的作用，同時(shí)也進(jìn)行相應(yīng)分析。通常只進(jìn)行30Hz以下，并針對(duì)幾個(gè)主要彈性模態(tài)（如車箱扭轉(zhuǎn)、地板呼吸和前彎曲模態(tài)）進(jìn)行模型相關(guān)性分析。座椅模態(tài)：詳細(xì)座椅模型的建模和模型相關(guān)性分析應(yīng)由座椅供應(yīng)商提供。但主機(jī)廠仍然要將座椅安裝在整車上狀態(tài)下進(jìn)行模態(tài)測(cè)試，將座椅側(cè)向模態(tài)和前后模態(tài)調(diào)整好。轉(zhuǎn)向系統(tǒng)模態(tài)：轉(zhuǎn)向系統(tǒng)模態(tài)測(cè)試是在將軸連接斷開，安裝在整車上進(jìn)行的。加速度傳感器務(wù)必不要放在塑料件上，但放在方向盤輪輻上是可以接收的。由于轉(zhuǎn)向系統(tǒng)管柱與整車坐標(biāo)系不對(duì)齊，就要保證分析模型與測(cè)試數(shù)據(jù)之間相互匹配。方向盤上的轉(zhuǎn)動(dòng)響應(yīng)數(shù)據(jù)在這個(gè)測(cè)試中是無法測(cè)量的。如果已安裝傾斜調(diào)節(jié)裝置，則本測(cè)試在平直狀態(tài)下再進(jìn)行一次。在50H在以下，針對(duì)兩個(gè)主要彈性模態(tài)（垂直彎曲、側(cè)向彎曲）進(jìn)行模型相關(guān)性分析。整車路面功率譜PSD響應(yīng)：在整車路面功率譜響應(yīng)模型相關(guān)性分析之前，必須進(jìn)行整車模態(tài)的模型相關(guān)性分析。測(cè)試駕駛員座椅導(dǎo)軌和轉(zhuǎn)向管柱/方向盤的加速度PSD數(shù)據(jù)。成功的路面PSD響應(yīng)模型相關(guān)性分析需要分析模型可以很好地模擬車輛和試驗(yàn)環(huán)境。車輛環(huán)境包括：車輛配置、設(shè)計(jì)發(fā)布狀態(tài)、駕駛員/乘員/測(cè)試設(shè)備重量、載重、胎壓、空調(diào)狀態(tài)、附件狀態(tài)等。通常車上液體狀態(tài)也要獲得的，如燃油、洗滌液、冷凍液、制動(dòng)液、機(jī)油等。測(cè)試環(huán)境包括：溫度、風(fēng)速、路面狀態(tài)、車速、起止位置等。如果可能，每次測(cè)試重復(fù)三次。整車路面噪聲：在進(jìn)行整車路面噪聲模型相關(guān)性分析之前，必須進(jìn)行整車模態(tài)、整車路面振動(dòng)和聲腔模態(tài)的模型相關(guān)性分析。整車路面噪聲測(cè)試與整車路面振動(dòng)測(cè)試一致，除了噪聲測(cè)試響應(yīng)在前排乘員耳旁或者其它位置。聲腔模態(tài)：聲腔模態(tài)模型相關(guān)性分析是在內(nèi)飾車身或整車狀態(tài)下進(jìn)行的。模態(tài)測(cè)試數(shù)據(jù)提取在頻率100Hz以下，最低彈性模態(tài)如第一階/第二階縱向模態(tài)、第一階側(cè)向模態(tài)，需要進(jìn)行相關(guān)性分析。座椅的等效質(zhì)量需要調(diào)整好以匹配測(cè)試結(jié)果。車體結(jié)構(gòu)與聲腔耦合：此模型相關(guān)性分析對(duì)應(yīng)的測(cè)試是在內(nèi)飾車身下頻率響應(yīng)測(cè)試。在每個(gè)車體上接附點(diǎn)輸入激勵(lì)，在駕駛員耳位置輸出聲壓響應(yīng)，即所謂聲音靈敏度，針對(duì)100Hz以下。Avehiclesystemmodelisacomplicatedsystemanditscorrelationtotestrequiresthatmanyofitsmajorsub-systembeingcorrelatedfirst.VehicleNormalModes:Toachievegoodcorrelationforvehiclesystemnormalmodes,eachmajorsub-systemnormalmodeshouldbecorrelatedfirsteitherasaseparatecomponentoraspartofafullvehicle.Thetypeofcorrelationneededforeachsub-systemisdescribedbelow.Cab/Body:Correlationoffree-freenormalmodesisrequiredfortrimmedbodystructure.Ifresources/timingallow,correlationoffree-freenormalmodesfortheBIWisrecommendedfirst.Duringthemodaltest,thetrimmedbodyorBIWisusuallysuspendedusingseveralairbagstosimulatefree-freeboundaryconditions.Becausetheairbagsarenotabsolutely‘soft’,therigidbodymodesareusuallybetween1.0Hzto5.0HzinsteadofzeroHz.Allsixrigidmodemodesshouldbemeasuredtoassurethat:1)thereisenoughseparationbetweentherigidbodymodesandthe1stflexiblemode;2)theycanbeusedtoimprovecorrelationascanbeseeninthefollowingparagraph.TheseairbagsshouldbesimulatedintheanalysismodelbyusingCELASelementsinthreetranslationaldirections.Theirstiffnessvaluesshouldbeadjustedsothattheanalysismodelhasthesamerigid-bodymodalfrequenciesasthoseofthetest.DuetothelargenumberofDOFsinboththetrimmedbodytestandthecorrespondinganalysismodel,correlationoffree-freenormalmodesisnormallylimitedto30Hzandonlyseveralmajormodessuchas:firstglobalbodybending/torsion/match-boxingmodes,FESMlateral/verticalmodes,roof/floorbreathingmode,seatlateral/fore-aftmodes.Foracousticstudies,correlationofmodeshigherthat30Hzmaybeneeded.Frame:Correlationoffree-freenormalmodesisrequiredfortheframestructure.Theframeshouldhavebumpersattachedbutitisoptionaltohavethesparetireorfueltank.Duringthemodaltest,theframeisusuallysuspendedusingseveralairbagstoprovideafreeboundarycondition.TheseairbagsshouldbesimulatedintheanalysismodelbyusingCELASelementswithtranslationalstiffness.Theirstiffnessvaluesshouldbeadjustedsothattheanalysismodelhasthesamerigid-bodymodalfrequenciesasthoseofthetest.Correlationoffree-freenormalmodesisnormallylimitedto30Hzandseveralmajormodessuchasfirstandsecondframeverticalbending,lateralbending,torsion,lateralmatch-boxingmodes.Suspension:Thegoalofcorrelatingthesuspensionistomatchthehopandtrampmodesoftheanalysismodeltothoseofthetest.Thesuspensionmodetestisnotstandardizedyet.ItistypicallyperformedonasmoothroadwiththevehiclegoingoverasAESbumpataspeedof10to15MPH.Thetrampmodeisexcitedwhenonesideofthevehiclegoesoverthebumpwhilehopmodeisexcitedwhenbothsidesofthevehiclegooverthebump.Accelerationresponseatthefourwheelspindlesarecollected.Afullvehiclesystemmodelshouldbeusedandeithernormalmodeanalysisortransientresponseanalysiscanbeusedtoextractthehop/trampmodes.Additionally,forhardwaretest,fourpostroadsimulatorsmayalsobeusedtoexcitethesuspensionsystemandextracthopandtrampmodes.Caremustbetakenwhenusingtheridesimulatorsincethetire/wheelsarenotrolling.Previoustestingexperienceforsuspensionhopandtrampmodeshasshownthatarollingtireislessstiffthananon-rollingtire.Thismeansthatthesuspensionhopandtrampnaturalfrequenciesmeasuredinthe4-postLabwithshakerswillslightlyhigherthanthosemeasuredontheroad.ExhaustSystem:Thecorrelationtestfortheexhaustsystemisacantileverednormalmodetest.Theexhausttakedownpipesandexhausthangersshouldbeattachedtoagroundedfixture.Ifnofixtureisavailable,theexhaustshouldbetestedwhileinstalledonthevehicle.Analysismodelscorrespondingtoeachtestconditionshouldbeused.Normalmodesupto50Hzshouldbeusedforcorrelation.Thehangerratescanbetunedtomatchthefirstcantileverlateralandbendingmodesoftheexhaustsystem.Attentionshouldbegiventotheexhaustpipeshape,diameterandthicknessbecausetheyhavetypicallybeenchangedfromtheirdesignvaluesduetothefabricationprocess.PickupBox:Thecorrelationtestforapickupboxisafree-freemodaltestinthelab.Thepickupboxisusuallysuspendedbybungeecordsorbyairbagstoprovidethefree-freeboundaryconditions.TheseelasticsupportsshouldbesimulatedintheanalysismodelbyusingCELASelementswithtranslationalstiffness.Theirstiffnessvaluesshouldbeadjustedsothattheanalysismodelhasthesamerigid-bodymodalfrequenciesasthoseofthetest.Ifpossiblethetestshouldberepeatedwithoutthetailgateofthepickupboxtostudyitseffect.Theanalysismodelshouldbesimulatedaccordingly.Normalmodesupto30Hzaretypicallyextractedfromthetestandseveralmajorflexiblemodessuchasboxtorsion,bedfloorbreathingandfrontbendingmodesshouldbecorrelated.Seats:Detailedflexibleseatmodelingandcorrelationshouldbedonebytheseatsupplier.However,wemaystillneedtoperformseat-on-vehiclemodaltestingtofine-tunesomeofthelowerseatmodesliketheseatlateralswingmodeandfore-aftmodes.SteeringColumn:Thecorrelationtestforthesteeringcolumnisanin-vehiclenormalmodetestwiththeintermediateshaftdisconnected.Accelerometersshouldbeattachedtosteelpartswheneverispossibleandnotonplastictrimparts.Accelerometersonvinylcoatedsteeringwheelrimisacceptable.Becausethesteeringcolumnisnotalignedwiththeglobalvehiclecoordinates,caremustbetakensothattheanalysismodeloutputisconsistentwiththetestdatacollected.Therotationalresponseofthesteeringwheelisnotmeasuredinthistest.Ifatiltmechanismisequipped,thetestshouldberepeatedforthesteeringwheelatthestraight.Normalmodesupto50Hzaretypicallyextractedfromthetestandtwomajorflexiblemodes,steeringcolumnverticalbendingandlateralbendingmodes,shouldbecorrelated.VehicleRoadPSDResponse:VehiclesystemnormalmodesshouldbecorrelatedfirstbeforethevehicleroadPSDresponsecorrelationstarts.Theaccelerationresponsesatthedriver’sseattrackandsteeringcolumn/wheelareusuallycollectedinaccelerationPSDformat.SuccessfulcorrelationofroadPSDresponserequiresthatthevehicleandtestconditionsbeingsimulatedarerepresentedbytheanalyticalmodel,oratleastnoted.Thevehicleconditionsincludevehiclecontents,designreleaselevel,driver/passenger/testequipmentweight,balla