Modern vehicles contain numerous subsystems for comfort, safety, electrification and autonomous driving functions that are mounted to the body-in-white structure. These subsystems are submitted to stochastic vibrational loads induced by the road unevenness. The vibration fatigue behaviour of the subsystems and their connection to the body-in-white structure depend on a great number of influence parameters and associated uncertain scatter bands that are usually unknown and difficult to consider in the design process.
This study investigates the oscillation behaviour and fatigue life of a current car component excited by vibrational loads focusing on scatter of relevant influence parameters (mass, stiffness) on a pronounced statistical sample basis. An experimental modal analysis is used to determine eigenmodes and damping characteristics for the 3 variants: nominal value, increased mass and reduced stiffness. As a further experimental investigation vibration fatigue tests are performed.
A simulation tool chain using commercial CAE programs is applied to consider scatter effects on the fatigue life of the component under vibrational loads and its connection to the body-in-white structure. The simulation quality when using uncertain broader scatter bounds is compared to simulation quality using measured data and modal analysis output. Furthermore, correlations between the vibration behavior and the fatigue of the component are derived. Finally, the hardware fatigue testing results are compared to the simulation results and conclusions are drawn.