Research On Automotive Interior Structural-borne Noise Control Based On Response Surface Method

The vehicle NVH performance has become an important specification to measure vehicle quality,and directly affects the decision of the customers whether to buy it. How to reduce the vehicle interior noise, improve vehicle NVH performance and riding comfort, has important economic and social benefits. In recent years, many research achievements have been made in vehicle interior noise control field. However, many issues need to be further studied, such as long analysis time and low computational efficiency. Therefore, based on the predecessor's literature research, and combined with the engineering practice, this thesis chose a B-class car of a domestic company as research object, built a structural optimization approximation model based on RSM (response surface method) with the objective of minimizing the root mean square of SPL (Sound Pressure Level) at measure point (Location of the driver's right ear). Then, we optimized the model by genetic algorithm, and decreased the vehicle interior noise by modifying the structural parameters of body panels, under the guarantee of comprehensive performances of automobiles.The main works are list as follows:(1) Modal analysis and vehicle interior noise analysis Aimed to investigate the problem of reducing the vehicle interior structure-borne noise, the car body finite element model is built, so as cavity sound field, modal analysis is performed to get the system vibration characters. Then we added white noise excitation to car body and calculated SPL at measuring point (Driver's right ear) Based on that, we predicted the vehicle interior structure-borne noise and determined the peak sound pressure and resonance frequency, to provide guidance for noise control.(2) Acoustic contribution analysis of panels Acoustic contribution of panel is applied to find out those car panel that have great effect on the peak sound pressure level at the driver's right ear, to provided reference for noise reduction by changing the body structural.(3) Research on automotive interior structure-borne noise control As the thickness of body panel among the structural parameters which directly affect the automotive interior structural-borne noise are important and easy to be changed, we build a structural optimization model with the thickness of those panel which contribution most to the noise level as design variables and the root mean square of SPL measured at the driver's right ear as the objective of minimizing. Considering the enormous computing time and low optimization efficiency in engineering optimization problems, we built the approximation model based on response surface method, then optimized the model by genetic algorithm. At last, we got a new set of thickness of the car panels after the optimization. In order to verify the interior noise is less than before the optimization, we compared the SPL at the driver's right ear. The results show that the peak sound level was decreased by the optimization, and the interior structural-borne noise reduction was achieved.Taking a B-class car as an example, the thesis investigates the problem from modal analysis, predicting the vehicle interior structure-borne noise, analyzing the acoustics contribution of body panel. Based on the RSM approximation model, this thesis established a design process and method in order to reduce the root mean square of sound pressure level at the driver's right ear by modifying the structural parameters of body panel. The studying result proved the research method on automotive interior structural-borne noise control based on RSM is feasible and effective.