CAE Dynamic Durability Simulation of Exhaust System

In order to have a robust exhaust system design a comprehensive durability analysis is required. This durability analysis should include thermal loads, engine vibration loading, and proving ground road loads. The dynamic performance evaluation in exhaust system development is a valuable tool to identify the best design alternative. The finite element analysis (FEA) applications in the design of automotive exhaust system have become an indispensable tool. Both the cost and cycle of the product development benefit from its usages. This paper presents a robust design procedure for the dynamic performance of exhaust system in a passenger vehicle. For dynamic analyses it is essential that the complete exhaust assembly is modeled, including manifold, a representation of the engine, and a flex decouple model. This is because dynamic excitation is predominantly comprised of unbalanced forces within the engine, which is transmitted to the exhaust system through the flex decoupling element. This paper presents the dynamic performance for the complete exhaust system and a DOE investigation approach for stiffness study of flex decouple. The first part of paper describes the dynamic performance evaluation of exhaust system in frequency domain and correlation of FEA model to experimental data. The correlation and updating of FEA is to ensure the representativeness of the FE model. The second part is the DOE study of the decoupling flex pipe to define the optimal stiffness parameters in order to reach the specified durability targets in exhaust system. In this paper all the employed methodology will be discussed in details.