Solution approach:

To analyse the causes of the problem, we carried out operational measurements. Through an initial FE calculation, we were able to show that the mounting bracket and the component mounted on it had a relatively low natural frequency (less than 40 Hz). By evaluating the measurement data (strain gauges and accelerations) of the operational measurement, we were able to show that the first bending eigenmode of the bracket and the component attached to it is dominantly excited by the operation mode. This subsequently leads to an early fatigue fracture. Using FE calculations, we were then able to find a constructive measure for the available installation space in order to change the natural frequency of the system and to detune it sufficiently. Within the scope of a second operational measurement, we determined the operational loads for the modified design and carried out a strength assessment with the validated FE model.

Results:

Our modified design significantly increases the operational service life so that the mileage of approx. 1.8 million kilometres required by the customer can be achieved.