中型客车排气系统模态分析及结构优化

Optimization and Modal Analysis of Medium Bus Exhaust System

针对某中型客车振动噪声问题,以中型客车排气系统为研究对象,采用试验与仿真两种方法获取排气系统的自由模态进行了分析,得到排气系统的固有频率,并验证了仿真模型;然后运用灵敏度分析,得到排气系统各薄壁件厚度对于第三阶固有频率的灵敏度;最后对敏感薄壁件厚度进行优化,使得排气系统固有频率避开发动机怠速时激励频率,有效改善车内噪声。

To solve the noise and vibration problem of a medium bus,two methods of testing and simulation were carried on in order to analyze modal parameters of exhaust system. Natural frequency was acquired and the simulation model is verified. Then the sensitivity value about the third order natural frequency to each thin-walled part's thickness is obtained by sensitivity analysis. Finally the thicknesses of sensitive thin-walled parts are optimized to keep the natural frequency of exhaust system away from the excitation frequency when the engine at idling speed. The NVH performance of medium bus is improved.