某轿车排气系统振动分析

Vibration analysis on car's exhaust system

联合有限元软件与AVL-EXCITE软件,对某轿车排气系统进行模态与强迫振动分析。首先利用有限元软件对排气系统做自由模态分析,初步分析其吊耳点布置合理与否。然后利用有限元软件对排气系统进行自由度缩减,提取其质量矩阵、刚度矩阵、主节点自由度信息及模态信息,整合到内燃机-排气系统多体动力学模型中,对排气系统进行受迫振动分析,充分考虑其弹性变形与模态共振对振动响应的影响。得出排气系统任一点上的振动响应及排气管路长度上的振动传递率,考察其振动耦合特性;为排气系统的空间走向和结构设计提供强有力的依据。

The modal and forced vibration analysis of the exhaust system of a car was carried out by using finite element software combined with AVL-EXCITE software. Based on the modal analysis of the exhaust system, the reasonableness of the drop zone layout of the exhaust system was preliminarily examined. Then the finite element software was used to reduce the degrees of freedom of the system to extract the mass matrix, stiffness matrix, the information of main nodes＇ degrees of freedom and the modal information of the exhaust system. These infornlations were integrated into a multi-body dynamic model, linking the internal combustion engine and the exhaust system. The forced vibration of the exhaust system was analysed, fully considering the impact of elastic deformation and modal resonance on vibration. Vibrations at any point of the exhaust system and the vibration transmissibility along the length of exhaust pipe were obtained, and its vibration coupling characteristics were studied; these give a strong basis for structural design and spatial direction arrangement of the exhaust system.