Abstract
Fatigue crack growth (FCG) in structures subjected to variable amplitude (VA) loading is a complex phenomenon. Analysing of FCG rate is important for the reliable life of engineering structures. It is difficult to model all the parameters influence FCG correctly due to the random nature of the VA loading as well as the number and complexity of the mechanisms involved in the FCG problems. . It has been found from the literature review that no universal model has been developed to analyse the crack growth condition under VA loading. In addition, no general understanding has also been agreed among researchers for any available models. Therefore, the main objective of this work is to investigate the FCG under VA loading based on FCG models also to propose a suitable model for VA loading. The work describes some of the FCG models for predicting the fatigue lives and FCG rates. For the simulation part of this study, towards prediction of crack propagation under cyclic, variable and random loading were used. The results had been carried out based on the Austen, modified Forman and NASGRO models. There are many factors affecting the FCG, which shown with great influence such as; initial crack length, load sequence, aspect ratio and stress ratio.
