Molecular dynamics simulation on PyC interfacial failure mechanism and shear strength of SiC/SiC composites

Abstract In this paper, a molecular dynamics simulation model was established for SiC/pyrolytic carbon (PyC)/SiC composites manufactured through a chemical vapor phase infiltration (CVI) process based on microscopic observation results to investigate the shear strength and failure mechanism of PyC interphase. The simulation results showed that due to the PyC interphase’s disordered structure, the carbon layer underwent non-planar shear, overlap, flip, and deflection during the shearing process, which increased the shear strength of the composites. In addition, when the strength of the PyC interphase was lower than the bonding strength with a fiber and matrix, failure was caused by the internal breakage of the PyC interphase; when the strength of the PyC interphase was higher than the bonding strength with a fiber or matrix, failure was caused by the debonding of the PyC interphase with a fiber or matrix.