Research On Acoustic Optimization Of Mini-Car Transmission House Based On Coupled Structural-Acoustic

The automobile industry is the support one of our national economic development. In the research, it is considered that the vibration and noise brought by the motional car is one of the most important guidelines and it affects the passengers' comfort. The vibration and noise of the automobile mostly comes from the engine and transmission system. However, automobile transmission system is mostly comprised of transmission. So it shows the especial crucial significance to knock down the vibration and noise of the whole car, by depressing the vibration and noise resulting from the transmission. Therefore, with the support of Chongqing science technology&commission (project number: CSTC, 2005AC6035), the automobile's transmission house has been taken for investigation object; the vibration and noise radiation of the transmission house is researched by combining with finite element and boundary element methods in this paper.The finite element model of the transmission house is built. The calculating mode analysis is carried out to get the inherent frequency and vibrational shape and so on. The experiment modal analysis is carried out and the error between calculating results and experimental results is limited. It is satisfied for the calculation request.The dynamic response of the transmission house is analyzed. The tested drive from the experiment is imported into the finite element model as the boundary condition, and the vibration distribution situation of the surface of the transmission house is figured out by frequency response analysis in Nastran.The boundary element model of the transmission house is built, and the vibration response of the house exterior is imported into the boundary element model by interpolation. Afterward, we can predict transmission house structural sound radiation and calculate the main acoustic result, such as sound pressure by software of Sysnoise.According to the fact that the radiation prediction of different running conditions is ineffective, a method to analyze the sound radiation characteristic of the automobile's transmission house based on the acoustic transfer vector (ATV) technology is proposed. The linear relationship between the acoustic responses of field points and the vibration responses of structure surface is calculated. Through the calculation of the acoustic transfer vector, the research of the transmission house's sound radiation characteristic to different running conditions is taken. The result shows that the free frequency affects the sound radiation greatly.The vibration and noise of the transmission house is measured. The experimental results and the calculating results are compared to prove the validity of structural noise prediction by FEM and BEM.