CRACK INITIATION IN UNIDIRECTIONAL BRITTLE-MATRIX COMPOSITES

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 initiates 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.