Failure Mode Analysis of Automotive Exhaust System Hot End

In this paper, a technical approach is proposed to solve the hot end failure issue of an exhaust system, which can increase the reliability and efficiency of FE calculation in the trouble-shooting process. An exhaust system in which the downpipe broke during the high speed road load test is taken as an example. In order to keep the virtual FE model consistent with the real operational conditions, lots of modifications are made, including mass correction, damping and Young's modulus. Also modal sensitivity analysis is performed to accelerate this correlation process between FEA and test, where the effect of Young's modulus, pipe wall thickness and isolator stiffness on the modal frequency is investigated. Based on the correlated FE model, the revised design is checked through inputting the engine dyno vibration data and stress levels are evaluated near the critical locations. It is validated by test that the revised design proposed following the current approach meets the durability target.