Test Correlation of an Exhaust System Durability Failure Using Enhanced CAE Approach

Durability of an exhaust system of an automobile is vital to its overall performance as well as customer satisfaction. Existing CAE approach involves simplified modelling & approximations and hence, offers a good scope to model critical details that have a definite bearing on the reliability of its prediction. In this work, an attempt has been made to capture all details such as effect of bolt pre-load on the rubber bushes/isolators, actual 3D model of the rubber bushes/isolators, material property based on measured load-deflection characteristics of the rubber bushes/isolators & contact interactions of mating surfaces that were apparently missing in the existing approach. All such modelling enhancements were incorporated in the model, which was then solved using non-linear solution technique. Different set of CAE results of modal, frequency response & harmonic fatigue analyses now correlate better with physical test results in terms of estimating fatigue life as well as identifying the location of actual failure. This has resulted into not only capturing the physics of the system more accurately, but also more confidence in the life/durability prediction, which will eventually reduce the development time of such exhaust systems through minimal physical testing of prototypes.