Damage evolution and lifetime of fiber-reinforced ceramic-matrix composites under stress-rupture with stochastic loading at intermediate temperatures

Abstract

In this paper, the stress-rupture of fiber-reinforced ceramic-matrix composites (CMCs) with stochastic loading at intermediate temperature is investigated. There are four different stochastic loading sequences under stress-rupture are considered with different loading time and time spacing. The micro stress filed of the damaged CMCs, the damage models of the matrix cracking, fiber/matrix interface debonding, and fiber failure consider the stochastic loading and time-dependent interface and fiber oxidation. The damage evolution of the stress-rupture strain, fiber/matrix interface debonding length and interface oxidation length, and the broken fibers fraction versus the time curves of SiC/SiC composite subjected to four different stochastic loading sequences are analyzed. The effects of the fiber volume, matrix crack spacing, fiber/matrix interface debonding energy, fiber/matrix interface shear stress, and environmental temperature on the damage evolution and lifetime of SiC/SiC composite are discussed. The experimental damage evolution and lifetime of SiC/SiC composite under stress-rupture with stochastic loading are predicted. Under stress-rupture with stochastic loading, the stress-rupture lifetime decreases with the stress level, and the frequency of the stochastic loading; the stress-rupture lifetime increases with the fiber volume, and decreases with environmental temperature; and the time for the interface complete debonding increases with the fiber volume, matrix crack spacing, interface debonding energy and interface frictional shear stress in the slip and oxidation region, and decreases with the temperature.