The fracture parameters describing the crack tip fields in functionally graded materials (FGMs) include stress intensity factors (SIFs) and T-stress (non-singular stress). These two fracture parameters are important for determining the behavior of a crack under mixed-mode loading conditions in brittle FGMs (e.g. ceramic/ceramic such as TiC/SiC). The mixed-mode SIFs and T-stress in isotropic and orthotropic FGMs are evaluated by means of the interaction integral method, in the form of an equivalent domain integral, in combination with the finite element method, and are compared with available reference solutions. Mixed-mode crack propagation in homogeneous and graded materials is performed by means of a remeshing algorithm of the finite element method considering general mixed-mode and non-proportional loadings. Each step of crack growth simulation consists of calculation of mixed-mode SIFs, determination of crack growth based on fracture criteria, and local automatic remeshing along the crack path. The present approach requires a user-defined crack increment at the beginning of simulation. Crack trajectories obtained by the present numerical simulation are compared with available experimental results. Other numerical results such as load and SIF history versus crack extension are also provided for an improved understanding of fracture behavior of FGMs.
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