Computer simulation of fatigue crack propagation under random loading conditions

The aim of this study is to simulate fatigue crack propagation under random loading conditions using a simple algorithm based on the Wheeler model [Wheeler O. Spectrum loading and crack growth. J Basic Eng D 1972;94:181-86]. To create the computer simulation, a model based on the mechanical properties of the material has been used. These properties include the yield stress (sigma(y)) and Paris's constants C and m. The loading conditions (baseline loading ratio R, baseline stress intensity factor range Delta K and overload stress intensity factor K-ol, R-ol) are also required. The present model is validated with fatigue crack growth test data conducted on 12NC6 steel samples with four different heat treatments in order to have different types of mechanical behavior. The computer simulation and experimental results for crack propagation for different overload distributions (a single overload, a repeated overload, different overload magnitudes, random overload) are in good agreement. (C) 2007 Elsevier Ltd. All rights reserved.