INPLANE SHEAR PROPERTIES OF 2-D CERAMIC-MATRIX COMPOSITES

The in-plane shear properties of a range of 2-D ceramic matrix composites have been measured using the Iosipescu configuration. The nonlinear deformation is found to be associated primarily with matrix cracks. Consequently, the shear modulus decreases as strain proceeds. The flow strength in shear is found to be compatible with the stress at which multiple matrix cracking is expected to occur, without interface slip. Consequently, the shear strength scales with the shear modulus. The shear ductility is found to diminish as the matrix modulus increases. This effect is attributed to the influence of matrix modulus on the bending deformation of fibers between matrix cracks. The experimental observations are used to suggest a mechanism map that identifies (class III) materials which redistribute stress around notches by means of shear bands.