Fracture analysis of semielliptical cracks at the interface of two functionally gradient materials using three-dimensional finite-element method

Abstract

Functionally graded materials are used as thermal coatings in the high-temperature applications such as aerospace structures, because of their good resistance against high temperature, wear, and oxidation. The purpose of this article is to study the fracture problem of semielliptical cracks between two functionally graded plates. The three-dimensional finite-element method is used to construct the mechanical models and calculate the stress intensity factors (SIFs) of interfacial cracks. For a special case, the validity of the finite-element model is examined. The effect of some relative parameters such as crack depth to thickness, crack length to crack depth (crack aspect ratio), plate width to thickness, plate height to thickness and relative heights of the plates, and also the effect of changing the modulus of elasticity on the SIF of the cracks are discussed. The results shown that there is a particular crack aspect ratio in which the maximum value of stress intensity factor changes from the deepest point to the surface point of the crack. Also, it can be concluded that the SIFs decrease with increase in the height-to-thickness ratio of the plate, but the plate width has no effect on the crack SIFs.