Automotive Components Fatigue and Durability Testing with Flexible Vibration Testing Table

Accelerated durability testing of automotive components has become a major interest for the ground vehicle Industries. This approach can predict the life characteristics of the vehicle by testing fatigue failure at higher stress level within a shorter period of time. Current tradition of laboratory testing includes a rigid fixture to mount the component with the shaker table. This approach is not accurate for the durability testing of most vehicle components especially for those parts connected directly with the tire and suspension system. In this work, the effects of the elastic support on modal parameters of the tested structure, such as natural frequencies, damping ratios and mode shapes, as well as the estimated structural fatigue life in the durability testing were studied through experimental testing and numerical simulations. First, a specially designed sub-scaled experimental testing bed with both rigid and elastic supports was developed to study the effects of the additional elastic support and the mass on the change of structural modal parameters. The significant modal parameters variation due to the additional elastic support was clearly illustrated by the experimental results. Moreover, the modal parameters with elastic support were then used to build and tune the finite element model (FEM). Afterwards, the accelerated durability profiles of both sine sweep and random vibration were applied to the FEM to compare the deviation of the cumulative fatigue damage between the tested structures with elastic and rigid supports. This work reveals and explains the inaccuracy of the current Accelerated Durability Testing system with rigid support foundation, which introduces a significant amount of variation in fatigue damage compared with the elastic foundation case for both Sine-Sweep and Random loading conditions while the dynamic properties of the tested structure with rigid support are different to the real situation.