Research On The Analysis And Control Methods Of The Vehicle Interior Structure Noise

The interior noise level is an important index for evaluating NVH performance of the vehicle, as well as one of vehicle capability that consumer concern. The pervasive analysis and control of it have become vital research content in automobile enterprises. Since modern cars are mainly installed using unitary construction body and different vibration sources vibrate the body directly, there are sorts of noise transmitted into cars. The car body is a main transfer path for noise, whose vibration characteristics react on the interior noise level. Thus, the dynamic characteristics of car body structures were analyzed in this paper. The control methods for interior noise were explored by studying the booming noise on a self-owned brand vehicle model.(1) The booming noise analyzed in this article is structure noise, which develop from the path where the vibration energy of transmission delivered through car body, body panel and the interior. The experimental and calculating modal analyses were applied on body-in-white and trimmed body respectively. The test and simulation meet a same conclude, that is, the natural frequency and mode of vibration in every mode can be validated. This can lay the foundation for control of noise and structure optimization.(2) The finite element model of interior acoustic cavity was put up and whose modal analysis was finished under traditional interior noise control idea. The body acoustic sensitivity was found less than 55 dB satisfied the design requirements.(3) The booming noise of the analyzed vehicle model still existed despite of enough acoustic sensitivity. Hence the transfer path analysis was implemented on the vehicle. The load identification was conducted using contrary matrix method at the point between sub-frame and car body. It was found that the body bears larger load at the mounting point of rear sub-frame.(4) The forced vibration of car body was calculated upon actual load. And the noise of interior target field point by simulation combining with acoustic cavity's mode analysis result coincided to the measured results. The vibration of body's middle-floor contributed more sound pressure to target field point by analyzing the contribution of body panel. The sound pressure of interior target field point declined and the control effect of noise stood out by optimizing the structure of body's middle-floor.(5) The idea was proposed that the Digital Mules Car can be applied on vehicle's early development stage aiming to predict the interior noise and guide the body structure to timely amend, which can reduce the risk of appearing interior noise when the vehicle was mass produced.