Fatigue crack growth prediction from low cycle fatigue properties

Abstract

The goal of this paper is the establishment of computation methods for the evaluation of the residual life of structural elements in the presence of initial damage which appears in the form of cracks. Initial cracks appear during the exploitation of structures in stress concentration zones. Therefore in this paper computation method for the evaluation of the residual life of structural elements with initial damage subjected to cyclic loading of constant amplitude is presented. Calculational methods for the evaluation of the residual life of structural elements with initial damage basically rely on crack propagation analysis. In this investigation for crack propagation analysis Strain Energy Density (SED) method will be used. This method uses the low-cycle fatigue properties of the material, which are also being used for the lifetime evaluation until the occurrence of initial damage. Therefore experimentally obtained dynamic properties of the material such as Paris' constants are not required when this approch is concerned. The complete method for the crack propagation analysis using low-cycle fatigue material properties is illustrated with the structural element in the form of a plate with a hole and a single initial crack. Results of numerical simulation for crack propagation based on strain density method have been compared with experimental results.