58485 - Micromechanical Modeling Tension-Compression Fatigue Hysteresis Loops Model of Fiber-Reinforced Ceramic-Matrix Composites Considering Fibers Failure 

In this paper, a micromechanical tension-compression fatigue hysteresis loops model of fiber-reinforced ceramic-matrix composites (CMCs) is developed considering fibers failure. Multiple fatigue damage mechanisms of fiber failure, interface debonding, slip and wear, and matrix fragmentation are considered and incorporated in the micromechanical fatigue hysteresis loops model. Upon unloading, the unloading stress-strain relationship is divided into four stages, including, (1) Unloading Stage I: the unloading interface counter slip stage and the unloading stress is between the tensile peak stress and the unloading transition stress; (2) Unloading Stage II: the unloading interface non-slip stage and the unloading stress is between the unloading transition stress and the matrix crack closure stress; (3) Unloading Stage III: the unloading partial compressive stage and the unloading stress is between the matrix crack closure stress and the unloading complete compressive stress; and (4) Unloading Stage IV: the unloading complete compressive stage and the unloading stress is between the unloading complete compressive stress and the compressive valley stress. Multiple micromechanical damage parameters of fiber failure probability, unloading/reloading transition stress, closure stress of the matrix cracking, compressive transition stress, complete compressive stress, unloading/reloading inverse tangent modulus (ITM), and interface counter slip/new slip ratio (ICSR/INSR) are adopted to characterize the tension-compression stress-strain hysteresis loops. Experimental tension-tension and tension-compression fatigue stress-strain hysteresis loops of unidirectional CMCs are predicted using the developed micromechanical models. The characteristics of the tension-compression fatigue hysteresis loops of unidirectional CMC are analyzed for different material properties, damage stage, tensile fatigue peak stress, and compression fatigue valley stress.