Adaptive Finite Element Modeling of Fatigue Crack Propagation

An adaptive finite element interactive program has been developed for fatigue crack propagation simulation under constant amplitude loading condition. The purpose of this model is on the determination of 2D crack paths and surfaces as well as on the evaluation of components Lifetimes as a part of the damage tolerant assessment. As part of a linear elastic fracture mechanics analysis, the determination of the stress intensity factor distribution is a crucial point. The fatigue crack direction and the corresponding stress-intensity factors are estimated at each small crack increment by employing the J-integral technique. The propagation is modeled by successive linear extensions, which are determined by the stress intensity factors under linear elastic fracture mechanics assumption. The stress intensity factors range history has to be recorded along the small crack increments. Upon completion of the stress intensity factors range history recording, fatigue crack propagation life of the examined specimen is predicted. Verification of the predicted fatigue life is validated with relevant experimental data and numerical results obtained by other researchers. The comparisons show that this model is capable of demonstrating the fatigue life prediction results as well as the fatigue crack path satisfactorily.