Numerical study on crack bifurcation of self-healing fiber-reinforced ceramic matrix composite

Abstract

Self-healing fiber-reinforced ceramic (shFRC) is a new functional material. When a microcrack propagates in this material, self-healing occurs owing to high-temperature oxidation. Then, the strength of the material recovers to its robust state since the microcrack is rebounded. However, to effectively demonstrate the self-healing function, a crack bifurcation, i.e., penetration/deflection, must be controlled. Therefore, the optimal composite design, in which the microcrack is induced in the interface along the fiber, is a key factor in developing shFRC. In this study, we investigate crack propagation using Finite Element Analysis (FEA). In FEA, the two-dimensional microscopic structure of shFRC with a three-layer construction is discretized. The three layers of construction are the matrix layer, the fiber bundle layer, and the non-oxide layer, called the self-healing agent. Using FEA, we examine ideal relationships of fracture stress and critical energy release rate between the fiber and interface layer considering the sintering characteristics. Furthermore, the relationship between fracture toughness, Young's modulus, and the relative density of the interlayer to induce a crack deflection at the interface is derived.

Keywords

• crack penetration/deflection
• fracture mechanics
• cmc
• fem
• cohesive zone model
• sintering