Analysis And Control Of Light Bus Interior Low Frequency Noise Based On Structural-acoustic Coupling Model

As people’s expectation on vehicle performance is getting higher, automobile ride comfort is bound to be used to highlight their own car brand as the bright spots by manufacturers. Therefore, the vehicle NVH(Noise,Vibration,Harshness)becomes an important factor on the design phase of the structure. It is critical to propose effective solutions quickly for the vehicle existing noise and vibration problems.In this paper, on the basis of cooperation projects with an enterprise, the light bus interior low frequency noise is analyzed by the finite element method combined with the test. Through the response analysis of vibration and noise of the structural-acoustic coupling model, some effective measures to reduce the interior low frequency noise are proposed based on the results of the structural modal participation and the panel participation.Firstly, according to the finite element modeling ideas and principles, the BIW(body in white) finite element model of this light bus was established and proven to be effective by the experimental modal test of the actual structure. The interior acoustic cavity FE model(finite element model) was established on the basis of the enclosed bus FE model and its modal was simulated. The structural-acoustic coupling model was established on the basis of the light bus structural and acoustic cavity FE model and its modal characteristics were analyzed before and after coupling.Secondly, the problem vehicle was tested on various working conditions by means of LMS test equipment. The peak frequency of interior acoustic response was determined by subjective evaluation and objective data analysis. And the suspension excitation and interior acoustic response were required in the test. The acoustic characteristics test experiment about was made to gain the acoustic response effect of interior materials such as seat foam, floor, sidewall, celling and so on.Then, the suspension excitation was applied on the structural FE model to simulate the light bus structural vibration response. The simulation results coincide well with corresponding experimental values, which verified the validity of structural FE model. The difference between interior simulation acoustic results and corresponding experimental values is acceptable through analysis of the light bus structural-acoustic coupling model, which indicated that the FEM(finite element method) acoustic simulation of coupling model was accurate and reliable.Finally, MPF(modal participation factor) and PPF(panel participation factor) analysis of acoustic response were conducted to confirm several structural panels that have a significant impact on interior low frequency noise. The interior noise was controlled effectively by pasting free damping layers and structural topography optimization on these body panels.