Karma modlu yorulma çatlağının genişletilmiş sonlu elemanlar metodu ile değişken genlikli yükleme altında yörünge ve ömür tahmini.

The main purpose of this study is to predict the crack growth path trajectories and fatigue crack growth (FCG) life under variable amplitude loading (VAL) by using Extended Finite Element Method (XFEM). For this purpose a computational algo- rithm is developed in Fortran which interacts with a commercial finite element soft- ware (Abaqus) and automatically propagates cracks which is initially modelled as stationary crack. Nasgro FCG equation is used for FCG life calculation which has a great accuracy among the FCG equations available in literature. Retardation effect due to VAL is taken into account by using appropriate retardation models according to nature of loading to show the capability of developed algorithm in covering the retardation phenomenon caused by overloads (OL) and underloads (UL). Developed algorithm is validated with several crack propagation tests available in literature in terms of crack growth path trajectories and FCG life under mode I and mixed mode loading conditions on different materials. Simulated and experimental results are in good harmony.M.S. - Master of Scienc