THE MODELING OF CRACK-PROPAGATION THROUGH THE INTERFACIAL REGION OF A SIC/TITANIUM METAL-MATRIX COMPOSITE

Finite element models of the interfacial region between a silicon carbide fibre and titanium metal matrix have been constructed using the Engineering Mechanics Research Corporation finite element package Display 3 and the Rasna Corporation package Astruct. The distributions of both tensile and shear stresses across the interface have been obtained and an elliptical crack of semi length 1.5 mu m introduced. The Young's moduli of fibre and matrix were varied from a nominal value of 360 GPa to 400 GPa for the fibre and 360 GPa to 92.3 GPa for the matrix; the resultant stress distribution showed that increasing fibre moduli dominated interfacial stress distribution, particularly directly in front of the crack tip, and increased the chance of crack propagation into the fibre. The stress intensity factors for a type I crack, in the interfacial region, using the finite element packages Endure and Applied Structure have been calculated and the results compared with theoretical calculations.