Random Vibration Fatigue Life Assessment of Transmission Control Module (TCM) Bracket Considering the Mean Stress Effect 2020-01-0194
Random loads are experienced by many engineering systems/components such as the housing and the brackets mounted on the chassis of an automobile, wind blowing on the wind turbine blades, Printed Circuit Board (PCB) used in battery electric vehicles, fuel cell stacks mounted on housing of a fuel cell etc. In automotive systems, random load is caused due to unevenness of the road surface. As these loads are varying in nature, it could lead to the fatigue failure of systems experiencing such loads. To ensure structural integrity, they are designed considering random loads and commercially used FE software packages have the capabilities available to evaluate random vibration fatigue. While above mentioned systems undergo random loads during operation, there are other loads/stresses also acting on them such as assembly loads (bolt preload), residual stresses due to casting, static loads i.e. load due to belt or chain drive etc. Consideration of all significant loads are extremely important for a design engineer and CAE analyst while designing such systems in order to ensure the reliability of their design.
The vehicle mount bracket is subjected to mean stress due to bolt preload and therefore, it should be addressed in random vibration fatigue assessment to ensure the safe design. The objective of this study is to consider the effect of mean stress in the random vibration fatigue assessment of Transmission Control Module (TCM) bracket made of polymer. The analysis is carried out for all the three directions without and with consideration of mean load using the modal superposition method utilizing modal coordinates to save the computation time. Results of without and with mean stress cases are compared to show the significance of mean stresses in designing the TCM bracket for durability.
Neeraj Carpenter, Sudeep Yesudas, Michael D. Nienhuis