A micromechanical loading/unloading constitutive model of fiber‐reinforced ceramic‐matrix composites considering matrix crack closure

Abstract Under cyclic loading/unloading, hysteresis loops appear due to the internal slip between the fiber and the matrix in the interface debonding regions of fiber‐reinforced ceramic‐matrix composites (CMCs). Hysteresis loops can be used as an effective tool to monitor internal damage evolution inside of CMCs. Within the present study, a micromechanical loading/unloading constitutive model was designed to predict the cyclic hysteresis loops of CMCs based on the matrix crack closure. A correlation was formulated between their hysteresis loops, matrix cracking density, loading/unloading inverse tangent modulus (ITMs), and interface reverse/new slip ratio (IRSR/INSR), as well as their dependence upon the material properties. In addition, different SiC/SiC composites (i.e., mini, unidirectional, cross‐ply, and 2D plain‐woven) were predicted based on the hysteresis loops, ITMs, IRSR, and INSR experimental results. The results indicated identical hysteresis loop peak strains for the samples both with and without matrix crack closure, though those without the matrix crack closure exhibited a lower hysteresis loop residual strain. All in all, the theoretical predicted results with regard to matrix crack closure were in correlation with the experimental data.