Vibration Analysis Of Exhaust System And Its Optimization

Exhaust system is an important component of vehicle, its main fuction is to deal with the exhaust and reduce noise. In the exhaust system design, the power loss, noise, emission and other issuses have been widespread concerned, but its dynamics is not given sufficient attention. One end of the exhaust system is connected to the engine though the exhaust pipes while the other end is bonded with the body though the hangers making the exhaust system an import path to transfer engine's vibration to the body. So it is necessary to study the exhaut's dynamics and vibration isolation issues.Exhaust system is complicated, it can't be desicibed with traditional vibration theory model. In this paper, the ANSYS software is applied to build the exhaust model for further dynamic analysis, besides an experiment is refered to verify the accuracy of the model. Numerical and experimental results show that the numerical model can express the exhaust's vibration characteristis. Therefore, the numerical model can be used for dynamic analysis.Modal analysis is a key dynamic calculation of the exhaust system. The exhaust's natural frequency must be kept away from the engine's stimulation frequency range as well as the body's, otherwise, the system will be coupled together to produce a strong responance. The modal analysis can be a theorical support to the design of exhaust. Through the exhaust's modal analysis, the mode nodes can be found, which is linked to the location of the hangers.Dynamic response anlysis of the exhaust is designed to analyze the force passed to the body. In the paper, harmonic analysis is applied to get the forces delivered by the hangers within 200Hz. Through modal analysis, the mode nodes are found, combined with hook layout requirements, the hangers'location is optimized in using of orthogonal experimental design to reduce the force passed to the body.Within the frequency range concerned, the optimization results show that: the optimized hangers's passing force is significantly reduced. The optimization has achieved a good result.