Considerations in Conducting Structural Dynamic Analysis of Commercial Vehicle Exhaust System

To validate the integrity of a commercial vehicle's exhaust system's structural design is a challenging job. An integrated approach to use both simulation/modeling and hardware testing must be employed to reduce product development cost. In addition to the considerations of the geometry and configuration specs of 70-90 parts and joints as well as material's thermal and mechanical property data in model development, representative loading must be used. For base excitation type of loading, such as the one experienced by the vehicle's exhaust system, one must decide whether to conduct the time domain transient analysis or frequency domain random vibration analysis. Although both methods are well known, few discussions can be found in the literature regarding their effective use in the framework of product design and development. Based on our study, the random vibration method should be used first for identifying high stress locations in the system and for design optimization. The modal transient analysis is conducted for product verification with the focus on the dynamic stress time history data of critical locations and cumulative damage calculation for life prediction. Discussions on advantages and limitations of each method are exemplified by the validation job of a commercial vehicle's after treatment device and system.