Finite element simulation of stress transfer through the multilayer interphase in ceramic matrix composites

The stress transfer through the multilayer interphase in ceramic matrix composites was simulated by finite element method. The microstructure of ceramic matrix composites(CMCs) was modeled by a cylinder unit-cell, the sub-layers of interphase were created according to their real thickness within the model. The interfaces between interphase sub-layers, interphase and fibers, interphase and matrix were all assumed to be bonded perfectly. Different material properties were defined for interphase sub-layers, and the axis-symmetry finite element method was applied to analysis the stress. After all, a simulation method for stress transfer through the multilayer interphase was developed. The simulation results for stress transfer within pyolytic carbon(PyC) interphase of different thickness, interphase of different constituents (PyC and SiC), and interphase of different structure ((PyC/SiC) and (SiC/PyC)) were compared. It can be seen from the distribution of stress along fiber and radial direction that the stress transfer and failure mode of interphase in CMCs can be controlled and optimized by rational allocation of the structure, constituent and thickness of multilayer interphase.