A methodology for numerical fatigue analysis of carbon fiber reinforced plastics Abstract: The main focus of this thesis is the development of a non linear energy dependent fatigue damage model for carbon fiber reinforced plastics (CFRPs). To achieve this task the fatigue behavior of carbon fiber reinforced plastics was investigated using online stiffness measurments.<br>Existing quasi static and fatigue models were assessed based on their potential to accurately describe the observed phenomenology. As a result the proposed strain damage energy based fatigue model combines the statistics of an S N curve with modified versions of the quasi static strain damage energy model of Ladevèze and the phenomenological fatigue life model of Van Paepegem. All required material parameters were calibrated using quasi static and constant amplitude loading experiments.<br><br>To validate the proposed fatigue model load block experiments were conducted. Those experiments were specially designed pure tension pure compression and mixed load experiments with constant and changing ratio R. The resualts obtained of the validation experimets are promising.<br><br>To further understand the fatigue behavior of carbon fiber reinforced plastics and to link the observed stiffness degradation to physical damage mechanisms destructive and nondestructive characterization methods such as microscopy and X ray tomography were used.<br><br>To conclude this work displays an overview of the damage mechanims quasi static and fatigue models for carbon fiber reinforced plastics. It also displays the experimental techniques to conducte fatigue experiments online measurments and non destructive characterization methodes. But most importantly it proposes a new promising strain damage energy based fatigue model for carbon fiber reinforced plastics