Analysis And Control Of Vibration And Noise For Shield Part

Due to the more stringent legislations of vehicle noise, the main noise source of vehicle—the noise of engine, has become more and more serious. For this, the research on the noise of engine surface emissivity is needed. So, the control of vibration noise for the shield part, which is the main noise source of engine surface emissivity, has become an urgent problem. In order to satisfy low level in vibration and noise of shield part, the analysis of dynamic performance and structure design should be utilized. The structure dynamic design based on the experimental model has become one of the most extensive research areas of vibration engineering. The development in FEM constructs the wider blueprint for the application of structure dynamic design. With the experiment of noise source identification, oil sump tank, exhaust manifold shield and two-way branch exhaust pipe shield are the main sources of surface radiate noise of a vehicle's engine. Using the finite element analysis software ANSYS, finite element model of the shield was established, then the modal analysis was done theoretically with this model, the result was consistent with the experiment. The result shows that this finite element model can be used for the next structual dynamic characteristics analysis. On this basis, the transient response of the shield under the excitation of engine block's vibration was analyzed for determining where was the main source of radiate noise. By this model, the relationship of structural parameter, structural style of the shield and the corresponding vibrative modal was analyzed. The optimal improved measures were adopted which was based on the practical structure of the shield. The contrast of model analysis, transient analysis and structural-acoustic coupling analysis for original and improved model shows that the increase of natural vibration frequency is visible, the vibration noise of the shield is suppressed distinctly.