For a reliable fatigue assessment of mechanical components testing on hydro-pulse rigs are performed and CAE methods are used in parallel. To achieve comparable results with both methods, it is necessary to correctly reproduce the loading and dynamic response of the virtual component. In this paper a method will be introduced that allows an improved fatigue calculation of dynamically loaded parts by applying correctly identified loads and by including the nonlinear contact behavior within the deformable structure. Based on a modal reduced simulation model specific contact modes will be generated and used to extend the mode base. Using the method of virtual iteration on a simulation model of a test rig, the correct loading
is calculated. An advantage of the modal approach is that the time domain simulations during the iteration can be carried through in reduced analysis time. For the following fatigue analysis the nonlinear vibration response of the model can be directly used. The described process will be demonstrated with an example of a test rig for car bodies, and validated by comparison of fatigue results from real testing and CAE analysis.