《汽车NVH》PPT课件

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1、汽车NVHNVHNoiseVibrationandHarshness(NVH)振动振动机理激励响应传播接受按激励RoadNoiseandVibrationPowerTrainNoiseandVibrationWindNoiseandVibration按频率LowFrequencyNVH(0-80Hz)HighFrequencyNVH(>80Hz)按工程计算顺序VehicleNVHBodyNVHPTNVHBasicTheoryFunction:mx”+cx’+kx=Fmx”+kx=0f=ù/2=(k/m)1/2/2ðànaturalfrequ

2、encyk=function(I,J)A:cross-sectionEandG:elasticmodulusI:areamomentofinertia(Ix=0.083bh3;J=0.229b3hforrectanglecross-section)J:polarareamomentofinertiaL:lengthordistancetoaxlesBodyNVHMetricsBodyNVHmetricsfocusonVibrationSensitivityresponseandAcousticat:Seattrackandsteeringw

3、heelforvibrationDriverandrearseatoccupantacousticsensitivityforairbornenoise.PeaksareduetoresonantmodesF(N)V(mm/s)p(dB)ForceInputatDrivingPointVibrationVelocityatDrivingPointInteriorSoundPressureSTRUCTUREP/FV/FWhatControlsBodyModes?Overallmajorbending&torsionmodescanbecont

4、rolledby:ArchitectureStiffnessMassDampingNaturalFrequencyatwhichmodeshapeoccursisgovernedby:GlobalStiffness:bending&torsionMassofBodyDistributionofthebodymassrelativetothenodalpointsBodyModes–Stiffness&DesignFactorsNVHStiffnessRequirementsImposedontheBodyStructureArchitect

5、urallayoutofstructuralmembersandpanelsdefineloadpaths,global/localmodesandattachmentpointstiffness.BeamIandJvaluesJointStiffnessBodypanelsandtheirperimeterstructuresprovideshearstiffnessforglobaltorsionmodes.Structuralpanelsprovidelocalstiffnessforcomponentattachmentpointm

6、obilities.Bodypanelsprovidemembranestiffnesswhichcontrolpanelresonance.WhatControlsBodyArchitecture(Structure)?MechanicalPackageInteriorPackageStylingCustomerRequirementsManufacturingFixturingAssemblySequenceStampingWeldingMaterialSelectionBodystructurevibrationmodes:Globa

7、ldynamicandstaticresponseforvertical/lateralbendingandtorsionLocaldynamicresponse(pointmobility–v/F)atbodyinterfaceswithmajorsubsystemsForcesappliedtothebodyshouldbelocatednearnodalpoints.Momentsappliedtothebodyshouldbelocatednearanti-nodes.Node(bending)Couples/MomentsVert

8、icalForcesBodyModes&ForceInputLocationsBodyinWhiteBendingStiffnessTorsionStiffnessModalAn