On The Simulation Of The Interior Noise Of A Light Bus

The Finite Element Method (FEM), the Boundary Element Method (BEM) and the Modal test technique are synthetically used to analyze the dynamic characteristic and the interior acoustic field of a light bus body in this thesis.At first, the Finite Method is used to calculate the vibration modal of the light bus body. And then, the finite model is checked and verified by the test results. The harmonic response is calculated based on the right finite element model, and the part of the light bus body where the vibration is larger is found.Secondly, the cavity model of the light bus is built by the CAE software. In the proceeding of the building, the interior structure of light bus body is simplified considering the frequency range and the analyzing techniques.On the basis of the finite element dynamistic analysis and the cavity model, the direct finite element method and the acoustic—vibration coupling method are separately used to analyze the interior acoustic field, and the calculated results are well matched with those obtained by test. In matching, we can find that the acoustic—vibration coupling method is better than direct finite element method in processing the acoustic problem with middle—low frequency. We can also find from the results that stiffness of the top part of the light bus body is weaker than other parts and the acoustic contribution of the top to the interior noise of the light bus part is also bigger. So the key of controlling the interior noise is how to reduce the vibration of the top part.The acoustic sensitivity includes the acoustic shape sensitivity and the acoustic admittance sensitivity. In order to optimize the interior sound field of the light bus, the Boundary Element Method and the functional analysis are conducted to calculate and analyze the acoustic sensitivity of the light bus body. Some useful results are obtained, which could be used to direct of acoustic optimization.