Low Frequency Structural-acoustic Coupling Noise Response Analysis And Control For Trimmed Car Body

As the development of vehicles in high speed and lightweight direction, the noise problemis getting more and more remarkable. The noise problem makes the ride comfort worse. At thesame time, people’s exception on ride comfort is getting higher. The auto manufacturers paymore attention on NVH (noise, vibration, harshness) characteristic of vehicle. The noisereduction is become a vital goal of automobile structure design.To seek out an effective method of vehicle interior low frequency noise control, thenumerical simulation analysis was conducted on the vibro-acoustic characteristic of a trimmedbody structural-acoustic coupling system. Based on the results of participation factor analysis,some effective methods to control vehicle interior noise are concluded. This research iscombined with school-enterprise cooperation project Research and Development of VehicleVibro-Acoustic CouplingAnalysis and Control.The BIW (body in white) FE model (finite element model) of vehicle was established basedon the finite element modeling principles. The model was verified by the experimental modalanalysis. The enclosed vehicle body model was built upon the BIW model. The vehicleacoustic cavity considering seats was determined by the enclosed body model and seat models.The modal test result of the vehicle interior cavity verified the validity of the acoustic cavitymodel. The structural-acoustic coupling model was formed by the enclosed body model andacoustic cavity model. Modal analysis was made to analyze the difference between couplingand non-coupling models. The acoustic performance test experiment was made to gain theparameters in order to build the FE model of the interior trim parts. The excitation of the frontand rear suspension, powertrain and exhaust systems mounts in different operation mode wereobtained according to the road test. The excitations were loaded on the timed body structural-acoustic coupling model to calculate the interior noise. The error of the simulation noise and test noise is less than±6%. It proved the validity of the coupling model.MPF (modal participation factor) and PPF (panel participation factor) analysis wereconducted to analyze the interior noise response. Two noise reduction methods were proposedaccording to the contribution analysis results. The decreasing amplitude of total SPL (soundpressure level) were4.45dB by pasting damping layer on the sensitive position or replacingthe front or rear windshield with PMMA-PVC glass. The noise reduction measures areeffective.