Simulation Analysis And Application Research On NVH Of A Coach Body

As China is a developing country with a large population, main trip mode for most people will still be coach for the coming long period of time. So, comfort and safety of the coach is attracting more and more attention of practitioners and manufactures. And, NVH has been attention focus among these aspects. Structure vibration can result in noise, of which propagations in and out of the coach can affect people’s health and even lead to traffic accidents. Noise produced by engine makes up more than half of total noise created by the whole coach. Though domestic practitioners have been doing some research in depth, there is a wide gap between internal and abroad research level. And nobody can solve such problems thoroughly.In this paper, an analysis of a coach modal and its characteristic of interior sound field has been done with a method of a combination of FEM and BEM. Main part of the research includes following points:Firstly, a coach frame finite element model, finite element model of the whole coach, boundary element model of vocal cavity, finite element of vocal cavity and their couple model have been built with HyperWorks software. Secondly, calculate modals of frame finite element model, finite element model of the whole coach (with HyperMesh) and vocal cavity (with Virtual.Lab), and get data of the first10order modals. Thirdly, import model of the whole coach and data of vocal cavity modals into Virtual.Lab, and calculate modals of this couple model with superposition method, then make a contrastive analysis of three models’ modal data. Fourthly, import coach model’s frequency response, which was calculated by HyperMesh, into Virtual.Lab and take it as boundary condition of vocal cavity analysis. Set5field points and calculate their sound pressure response curve. Fifth, calculate panel contribution amount with ATV technology after dividing vocal cavity into smaller parts which could be used in the aspect of noise reduction design of coach. Different precepts can be proposed according to different design with the same method described above.