Fatigue crack growth analysis of cracked specimens by the coupled finite element-element free Galerkin method

This paper presents a novel approach based on the coupled finite element (FE) and element free Galerkin (EFG) method to model fatigue crack growth in 2-D specimens containing different types of material discontinuities like holes and bi-material interfaces. In this approach, EFGM is used to discretize the domain near the crack whereas the conventional FEM is employed in the rest of the domain. The shape functions of the transition elements have been obtained by using the ramp function. The level set method has been used to track different discontinuities present in the domain. Finally, several two dimensional numerical problems are presented to demonstrate the applicability and efficiency of the proposed technique in modelling fatigue crack growth in presence of material discontinuities. The effect of various material irregularities on fatigue life, critical crack length and crack growth paths has been investigated in the present study. The results show that the critical crack length and the fatigue life of the cracked component reduce due to the presence of a weak bi-material discontinuity in it. The weaker discontinuities increase the fatigue life of the cracked specimen, whereas the stronger discontinuities slightly increase the fatigue life of the cracked component. The presence of holes in a cracked specimen reduces the fatigue life and the critical crack length at final failure. It was also observed that the holes and the weaker discontinuities exert some sort of attractive effect on the crack during its propagation through the domain.