Finite element evaluation of mixed mode stress intensity factors in functionally graded materials

This paper is directed towards finite element computation of fracture parameters in functionally graded material (FGM) assemblages of arbitrary geometry with stationary cracks. Graded finite elements are developed where the elastic moduli are smooth functions of spatial co-ordinates which are integrated into the element stiffness matrix. In particular, stress intensity factors for mode I and mixed-mode two-dimensional problems are evaluated and compared through three different approaches tailored for FGMs: path-independent J(k)*-integral, modified crack-closure integral method, and displacement correlation technique. The accuracy of these methods is discussed based on comparison with available theoretical, experimental or numerical solutions. Copyright (C) 2001 John Wiley Sons, Ltd.