Methodology to Arrive at Passing Criteria of Plastic Parts Subjected to Vibration Fatigue

In research and development of any automotive industry the main challenge is to virtually simulate probable failures rather than relying on physical testing which consumes time and resources. It is even more challenging when it comes to failure prediction of ABS plastic parts due to its complexity in material, behavior and assembly variations. ABS material is used extensively in automotive vehicles especially in motorcycles and scooters due to its visual and structural benefits at moderate cost. In this paper, the work showcases a methodology to predict failure of ABS parts. In order to do so, understanding the shortcomings in the current system is necessary. With the help of testing database history of various vehicles on proving grounds, root causes and drawback with respect to current simulation process are identified for failure of ABS parts. The input excitations from proving ground are probabilistic, thus, random vibration fatigue process is then introduced to calculate life. By correlating the simulation predicted life with testing, the required factor of safety to include residual stresses, assembly stresses are calculated and passing limit in terms of stress is derived for ABS parts to further reduce the simulation run time. Using six sigma methods, the accuracy in simulation is improved with which cycle time, prototype cost and testing time is reduced.