Effect of pre-fatigue loading on tensile damage and fracture of fiber-reinforced ceramic-matrix composites

Abstract

In this paper, the effect of pre-fatigue loading on tensile damage and fracture of fiber-reinforced ceramic-matrix composites (CMCs) is investigated using a micromechanical approach. Under cyclic fatigue loading, the fiber/matrix interface shear stress degrades with applied cycles due to the damage mechanism of the interface wear. The micro stress field of the damaged composite including matrix cracking, fiber/matrix interface debonding, and fiber failure is obtained for the fiber and the matrix axial stress and the fiber/matrix interface shear stress in the interface wear region, interface debonding region, and the interface bonding region, respectively. The fracture mechanics approach, stochastic matrix cracking model, and global load sharing (GLS) criterion are used to determine the interface debonding length, matrix cracking density, and fiber failure probability at higher applied stress level considering the damage mechanism of the interface wear. The effects of fiber volume, matrix cracking, fiber/matrix interface shear stress, fiber strength, pre-fatigue peak stress, and number of cycles on pre-fatigue tensile damage and fracture of SiC/SiC composites are analyzed. The experimental tensile damage and fracture of SiC/SiC composites with and without pre-fatigue loading are predicted for different interface properties.