Crack Initiation in Unidirectional Brittle‐Matrix Composites

Abstract

This paper describes the initiation of matrix cracking for glass and glass‐ceramic matrix composites reinforced with small‐diameter silicon carbide and carbon fibers under uniaxial tensile loading. Acoustic emission, replication, and optical microscopy in conjunction with stress‐strain curves are employed to detect the initiation of matrix cracking. The proportional limit of the stress‐strain curve is found to overestimate the initiation of matrix cracking in the material systems studied. The matrix cracking iniates at axial strains from 0.07% to 0.15%. The ACK model overestimates the initiation of the matrix cracking for the material systems studied in this paper.