Fracture Mechanical Investigations on Unidirectional Boron-Aluminum and Boron-Epoxy Composites

Abstract

The paper presents the results of investigations on DEN (double edge notched) specimens of different crack lengths. With the moire method the shear deformation at the notch tip has been measured. The boron-epoxy composite shows severe shear deformation resulting in matrix cracking parallel to the fibers. Extensive matrix cracking does not occur in notched B-Al. The net fracture strength at crack extension depends on the amount of shear deformation or shear crack formation at the notch tip. This de formation is a function of the crack length. The usefulness of linear elastic fracture mechanics (LEFM) has been investigated with the aid of the net fracture strength at crack extension as a function of the crack length.