Effect of Multiple loading sequence on in-phase thermomechanical fatigue hysteresis of silicon carbide fiber-reinforced ceramic-matrix composites

摘要

In this paper, the effect of multiple loading sequence on the in-phase (IP) thermomechanical fatigue (TMF) hysteresis of silicon carbide fiber-reinforced ceramic-matrix composites (SiC-CMCs) has been investigated. Considering the coupling effects of multiple loading sequence, thermal cyclic temperature and applied cycle number, the fiber/matrix interface damage lengths have been determined based on the thermomechanical micromechanical stress field and fracture mechanics method. The relationships between the in-phase TMF hysteresis loops, multiple loading sequence, thermal cyclic temperature and fiber/matrix interface damage state have been established. The in-phase TMF stress/ strain hysteresis loops and fiber/matrix interface damage state for different composite material properties, peak stress with different loading sequence and damage state have been discussed. The comparisons of the in-phase TMF stress/ strain hysteresis loops and fiber/matrix interface damage between single peak stress and multiple loading sequence have been analyzed. The TMF stress/strain hysteresis loops and fiber/matrix interface damage state of 2D SiC/SiC composite subjected to low-high three loading sequences have been predicted. Under TMF multiple loading sequence, the fiber/matrix interface slip lengths are larger than those under TMF single peak stress, leading to the increase of TMF stress/strain hysteresis loops area, peak and residual strain, and the decrease of hysteresis modulus.