Thermomechanical fatigue damage development of continuous carbon fiber-reinforced ceramic-matrix composites subjected to different loading sequences and phase angles

Abstract

Under thermomechanical fatigue (TMF) loading of fiber-reinforced ceramic-matrix composites (CMCs), the multiple TMF damage mechanisms of matrix multicracking, fiber/matrix interface debonding, and sliding are affected by the loading sequence and phase angle. In this paper, the TMF damage development of carbon fiber-reinforced CMCs is investigated corresponding to different loading sequences and phase angles. The TMF damage evolution subjected to different loading sequences (i.e., constant fatigue peak stress, low-high fatigue peak stress, and high-low fatigue peak stress) and phase angles (i.e., θ = 0, π/3, π/2, and π) are analyzed. The effects of fiber volume fraction, matrix crack spacing, fiber/matrix interface debonded energy, initiate/steady-state fiber/matrix interface shear stress, and thermal cycle temperature on the TMF damage evolution are discussed. The experimental TMF damage evolution of fatigue peak strain and hysteresis modulus versus applied cycles curves of 2D and 2.5D C/SiC composites at elevated temperatures of 550 and 800 °C in air condition are predicted.