Q/SZJ191001-2017硬點頻率響應分析規(guī)范(模態(tài)識別)SpecificationofPointFrequencyResponseAnalysis(modesIdentification)20XX20XX-12-31實施20XX-11-27發(fā)布XXXX汽車工程技術(shù)有限公司發(fā)布Q/SZXX-X-2017硬點頻率響應分析(模態(tài)識別)范圍本標準規(guī)定了術(shù)語和定義、硬點頻率響應(模態(tài)識別)分析方法及結(jié)果處理方法。本標準適用于CAE部門的硬點頻率響應(模態(tài)識別)分析。規(guī)范性引用文件無。術(shù)語和定義無。摘要Abstract白車身和內(nèi)飾車身通過24點或者26點法對車身結(jié)構(gòu)進行了基于傳遞函數(shù)的頻率響應分析，通過固有頻率和振動幅值從而準確識別出所需模態(tài)。BIWorTrimBIWmodelwillbesubjectedtoshakerloadsasafunctionoffrequencyandtheamplitude(acceleration)ofvibrationsareaveragedat24or26evaluationpointsonthebody.Thisanalysispredictsthenaturalfrequencyofthesystemandtheamplitudeofvibrationatthosefrequencies.

流程圖ProcessFlowDiagram收集詳細模型(白車身或內(nèi)飾車身)收集詳細模型(白車身或內(nèi)飾車身)CollectDetailedModels(BIWorTrimmedBody)創(chuàng)建所有評估點（24點或26點）CreateNASTRANnodesetatallevaluationpoints.（24or26evaluationpoints）輸出評估點幅值或者相位Outputallevaluationpoints提交計算NastranSOL111RunNastranSOL111設置邊界條件和載荷SettheboundaryConstraintsandLoads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)時間(Time) 秒(Second)內(nèi)容Contents白車身或者內(nèi)飾車身。BIWorTrimmedBody.坐標系CoordinateSystems分析采用整車坐標系，有些彈簧需要建局部坐標系。Analysisusevehicleglobalcoordinatesystem,andlocalcoordinatesystemsareneededforsomespringsinthetrimmedbody.建模技巧ModelingTechniques無。假設和限制Assumptions/Limitations阻尼是測量振動振幅所需的基本特性。假設白車身阻尼為0.8%和內(nèi)飾車身阻尼為3%。Dampingofthesystemisanessentialpropertyrequiredtomeasuretheamplitudeofvibration.ForBIWsystem0.8%dampingisassumedandforTrimBIWsystem3%dampingisassumed.載荷和邊界條件Loads/BoundaryConditions為了模擬測試狀態(tài)（把白車身固定在四橡膠墊上），自由狀態(tài)沒有約束(在整個模型的情況下)。如果使用半個模型，則必須在對稱平面上使用以下邊界條件。對稱模型約束自由度2、4、6(僅限半模型)不對稱模型約束自由度1、3、5Tosimulatetestconditions,wherethebody-in-whiteislocatedonfourrubberballoons,thesimulationisperformedwithoutconstraints(incaseofanentiremodel).Ifahalf-modelisusedforsimulationthefollowingboundaryconditionsmustbeusedatthesymmetryplane.Gridatsymmetryplane:symmetric2,4,6(Halfmodelonly)asymmetric1,3,5用一個諧波單位載荷來激發(fā)結(jié)構(gòu)。頻率響應的范圍從10到250Hz，步長為1Hz，載荷施加在前、后縱梁的前部和后部。有以下三種工況（圖2所示）：工況1：彎曲工況4個點同時施加同方向垂向載荷,查找彎曲模態(tài)。工況2：扭轉(zhuǎn)工況對角線加載同向載荷，另一對角線反方向加載，查找扭轉(zhuǎn)模態(tài)。工況3：側(cè)向工況4個點同時施加側(cè)向載荷，查找側(cè)向模態(tài)。圖2載荷示意Fig2AppliedLoadsAharmonicunitloadisappliedtoexcitethestructure.Thefrequencyresponseisevaluatedinarangefrom10to250HzinstepsofoneHz.Loadsareappliedatthefrontandrearlongitudinalsatthefrontandrearofthestructure.Thefollowing3subcasescanbecreated(showninFigure2below):1.Verticalloadsatall4pointsinphase.Thiscreatesthebendingloadandhencebendingfrequencies.2.Verticalloadsatfrontandrearandleftandrightbeingoutofphase.Thiscreatestorsionloadandhencetorsionfrequencies.3.Lateralloadsatall4pointsinphase.Thiscreatesthelateralbendingloadandhencelateralfrequencies.請參閱白車身或內(nèi)飾車身建模指南。在車身兩個側(cè)面共取24或26個響應點如圖3。所有的響應點在NASTRAN里面創(chuàng)建一個集（set）。圖3車身響應示意圖Fig3EvaluationPointsonBody結(jié)果Results輸出響應點的加速度響應。Theaccelerationresponseoftheoutputresponsepoint.頻率與振幅曲線如圖4。圖4頻率與振幅的曲線Fig4frequencyvs.amplitudecurves性能要求PerformanceRequirements白