A Computational Model for Progressive Damage and Failure of Fiber-Reinforced Ceramic Composites.

A computational model was developed to simulate the progressive damage of fiber-reinforced brittle matrix composites under uniaxial tensile loading. In conjunction with the basic material properties, this model used a size-distribution of the 'fiber-free zones' as an input for the development of small penny-shaped cracks at the early stage of loading. Stable extension of such non-steady-state cracks and the transition from non-steady-state to steady-state cracks were modeled using a stress-intensity formulation for a partially-bridged penny-shaped crack. Stress-strain relation was simulated by calculating the total engineering strain in the gage section as a function of the applied stress. Strain energies of the non-steady-state cracks and displacements of the fibers in the sliding zones of the steady-state cracks were calculated to estimate the total strain. Two unidirectional fiber-reinforced composites were investigated to test the predictive capability of this model. The stress-strain relation predicted by the model was in good agreement with that measured experimentally for a SiC-reinforced calcium aluminosilicate composite. A SiC-reinforced magnesium aluminosilicate composite showed less cumulative strain before fracture due to premature fiber failure. (MM)