The Analysis And Design Of Vibration Isolation Of The Vehicle Exhaust System

With the development of automotive industry, automotive NVH performance has becomeanother important performance index besides the safety and fuel economy, which has drawn attentionfrom the public. Since its complex structure and the direct connection with the engine and the body(or frame), the property of exhaust system will directly affect the vehicle NVH performance. So theanalysis of vibration and research on exhaust system has a very important value on engineeringapplication.Due to the complexity in its structure, the exhaust system can’t be directly modeled by theclassical vibration theory and simplified model. Therefore, on the basis of modeling variouscomponents of the exhaust system, the actual structure of exhaust system was taken into account. Andits three-dimensional numerical simulation model was established with the application of finiteelement method. The vibration model numerical analysis of exhaust system was completed byANSYS. The exhaust system vibration modal test results were used. The natural frequencies andnatural mode shapes (MAC value) were taken as index to verify the exhaust system numerical model.The sensitivity analysis on the important components of exhaust system (exhaust bellows, hangers,etc.) was performed and researched the exhaust system’s vibration influence law of the main parts’design parameters. The dynamic force of exhaust system hangers was taken as target. Both theentirely and partially arrangement of exhaust system suspension points was designed and optimizedwith the application of modal displacement method and the orthogonal design. Bellows, hangerposition, hanger stiffness and other factors were integrated. Then a comprehensive evaluation onhanging force indicators was acquired and optimal combination of parameters was got.So theoptimization of the exhaust system vibration was achieved. Aimed at the idle resonance frequencyproblems existed in certain exhaust systems, the problem of exhaust system idle resonance was solvedthrough sensitivity analysis and design of the exhaust system.The three-dimensional finite element model of the exhaust system built in this paper, thesensitivity analysis and optimization method of multi-factor vibration provides reference value fordesign and analysis of vibration Isolation of the exhaust system.