Analysis And Optimization Of Automotive Body Vibration Noise Characteristics

The performance of NVH is an important indicator to evaluate a vehicle. The automobile manufacturers pay more and more attention on how to improve vehicle‘s NVH performance as the laws getting more strict and the consumers‘ requirements for comfortable is higher. So it?s a great significance to improve the NVH character. The interior Noise is a major factor to influence the vehicle‘s NVH performance, and it gives a direct impression to the consumers. Based on one vehicle as the research object in this paper, a series of analysis to lower the interior Noise are finished, mainly include:(1)The FE model is build based on the geometry model, and the analysis of free modals of the vehicle body include BIW、engine hood、vehicle doors、and hatchback are made to realize the dynamic characteristic of the vehicle body. The FE and BE models of the interior cavity are built to get the acoustic modal shape and frequency. The differences of the acoustic characteristics between the cavity model with and without seat are analyzed.(2)By exciting the engine mounts, the acoustic response at the position of the driver‘s ear is calculated based on acoustic transfer vector(ATV) approach。And the panels that with greater contribution to the noise level of driver‘s ear are found.(3)The thickness of the panels are optimized to lower the noise level of the driver‘s ear. The sample points are designed based on the theory of the Design Of Experiment(DOE),and a Response Surface Model(RSM) is set up to reflect the relationship between the variables and the noise level, then the optimal solution is found by the Multi-Island Genetic Algorithm.(4)Combined with modal strain energy analysis and the result of Panel contribution analysis, the structure of the vehicle body is processed with damping material to further reduce the noise level of the driver‘s ear.In summary, this paper systematically studies the interior noise in low frequency. The results have important theoretical significance and engineering applications for improving vehicle NVH performance.