Estimation of Ct of functionally graded materials under small scale creep stage

The crack growth life assessment procedures at high temperature developed for homogeneous creep materials need to be extended to functionally graded materials (FGMs). In this paper, a proposed method was used to estimate Ct of a FGM with a creep crack paralleling to the material properties’ gradient direction. Finite element method (FEM) was used to verify the method. The FEM results indicated that the method could exactly estimate Ct under the small scale creep stage. Since the method is independent of the gradient variation law of material properties, it can be extended to any kind of gradient variation law of material properties.