Effect of interface properties on the nonlinear behaviour of long-fibre-reinforced unidirectional ceramic-matrix mini-composites subjected to tensile and fatigue loading

In this paper, the effect of the interface properties between the fibre and the matrix on the nonlinear behaviour of long-fibre-reinforced unidirectional ceramic-matrix mini-composites (mini-CMCs) is investigated. The tensile nonlinear constitutive relationship and fatigue loading/unloading constitutive relationship are developed considering the different damage mechanisms of cracking in the matrix, debonding in the interface, and gradually the broken fibres. The relationships of the interface properties between the fibre and the matrix, the nonlinear tensile strain, and the fatigue loading/unloading hysteresis loops are established. The effects of the interface properties between the fibre and the matrix on the nonlinear tensile and fatigue loading/unloading damage evolution are analysed. The nonlinear tensile strain at the damage stage and the fracture strain of mini-CMCs decrease with the strong interface properties; and the fatigue loading/unloading hysteresis loops area and strain decrease, and the hysteresis modulus increases with the strong interface properties. The experimental tensile stress-strain curves and fatigue loading/unloading hysteresis loops of the Hi-Nicalon^TM and Tyranno^TM SiC/SiC mini-composites are predicted corresponding to the different interface properties.