Material damage integration approach for efficient modelling of high cycle fatigue

Abstract

The recognition of the risk of fatigue failure and its study, particularly fatigue crack growth (FCG) behaviour of engineering materials, is not neoteric, and the majority of approaches for investigating the problem are empirical and dated. With recent computational advances, the cohesive zone modelling (CZM) approach for FCG analysis has become popular especially amongst researchers owing to its flexibility of use particularly within the finite element framework. However, the use of the CZM for explicit cycle-by-cycle high cycle FCG analysis of real structural components is still largely computationally prohibitive. Thus, this study presents a novel material integration (MI) approach to accelerate fatigue crack propagation within the cyclic cohesive zone modelling (CCZM) framework. Using a bilinear cohesive law, the proposed technique is compared with the Linear Extrapolation (LE) technique and assessed for three models of different bulk-interface element discretisation and deformations. The results show that the MI technique offers a more consistent approximation to the accelerated fatigue damage computation and, more importantly, better convergence characteristics for the different models under tension, mixed mode and bending deformations. These outcomes underline the computational benefits of the proposed MI technique in assessing the FCG behaviour of real structural components within the CCZM framework.