The Vibration-Noise Simulation And Control Of Automobile Body Acoustic-Structure System

With the rapid development of automotives, as well as the vehicle safety and dynamic performance, customers now pay more attention to the vehicle NVH.This paper firmly combine FEM and BEM to reliaze the vibration-noise simulation,and then use APDL parametric language to realize closed-loop control. This paper effectivly connect the soft ANSYS and SYSNOISE to do the analysis.Then with car model which established in ANSYS, do the model analysis from three parts:car body, compartment cavity sound field including seat and without it and acoustic-structure coupling system. The conclusion of analysis is that the acoustic-structure modal has strong relationship with the car body and acoustic modal. Besides it, the existence of the seat makes the tune modal no longer symmetrical, the section line position is not continuous. As a result, compare to the modal with seat, the modal frequency of acoustic modal without seat is slightly lower, the vibration mode almost the same.The research of this paper also involve in the dynamic parts of car body, compartment cavity sound field, and acoustic-structure coupling system. On this basis, the dissertation analyzes car compartment acoustic response of coupling system by the stimulation of the engine. It concludes that vibration peak frequency mainly under100Hz and the roof vibration is almost to be a major noise source. By comparative analysis of acoustic model and acoustic-structure coupling system, obtain the sound pressure of measuring points beside driver’s position. As s result, the noise level is almost the same, it is slightly increased in the peak sound pressure and certain peak has a frequency shift. Further do panel acoustic contribution analysis, it concludes that front firewall, rear door, back floor and roof panel have something done with the noise and are mainly contributed to car interior noise.Finally, upon the former chapters’results, then do the control from the roof. By sticking the piezoelectric material on roof, obtain conclusion that:the middle feedback, no matter what kind of control can not get good result; The vertical ratio feedback control with the opposite effect, however, constant feedback control achieve good results only in the0.18s;The horizontal ratio feedback control has down the vibration in the0.2s. In a word, it suggested that the use of horizontal proportional control.