I wrote my BSc thesis at Knorr-Bremse Commercial Vehicle Systems in 2010. Project task was to investigate and compare different kinds of frequency based fatigue lifetime calculation methods excited by random vibrations. The frequency based calculation methods were used in order to determine the fatigue lifetime of a clutch servo model. The model geometry was imported into Ansys Workbench. First, a solid structural simulation was done for the pretension of the screws then random vibration simulations were made in the x, y and z directions. After that, the results were exported into another programme (nCode DesignLife) which can calculate fatigue lifetime numerically with different frequency based models. The numerically calculated results were compared with analytical hand calculations (Steinberg 3 sigma model).
