Estimate interface frictional coefficient of ceramic matrix composites from hysteresis loops

An approach to estimate fiber/matrix interface frictional coefficient of ceramic matrix composites under fatigue loading is developed by means of hysteresis loops. The Coulomb friction law is adopted to describe the interface shear stress in the debonded region. The matrix crack space and interface debonded length are obtained by matrix statistical cracking model and fracture mechanics interface debonding criterion. The hysteresis loops of four different cases are derived based on the damage mechanisms of fiber sliding relative to matrix in the debonded region during unloading and subsequent reloading. The hysteresis loss energy corresponding to different cycle is formulated in terms of interface frictional coefficient. By comparing the experimental hysteresis loss energy with computational values, the interface frictional coefficient of three different ceramic matrix composites under fatigue loading is derived.