The effect of fiber-matrix debond energy on the matrix cracking strength and the debond shear strength

Abstract

The matrix cracking model given by Budiansky, Hutchinson and Evans [ J. Mech. Phys. Solids 34, 167 (1986)] is extended to include the effect of fiber-matrix bonding in a unidirectional fiber-reinforced composite. By use of an energy balance analysis, the work of debonding Γ d is related to a characteristic critical interface shear stress τ d and to the frictional interface sliding resistance τ f by the expression τ d − τ f = √4 G m Γ d/ av, where G m is the matrix shear modulus, a, the fiber radius, and v the function of fiber volume exceeds the background fiber tensile stress far from the crack by a fixed calculable amount. Finally, the combined effect of τ f and adhesion on the intercrack spacing is predicted for the case where multiple cracks develop in the matrix.