ROLE OF FIBER STITCHING IN ELIMINATING TRANSVERSE FRACTURE IN CROSS-PLY CERAMIC COMPOSITES

A theoretical study of the feasibility of using fiber stitching to pre vent transverse matrix cracking in cross-ply ceramic composites is rep orted. The prototype problem solved is a curved composite beam subject to pure bending (the C-specimen), which develops a transverse tensile stress sigma(0) acting across its circumferential midplane. Fiber sti tches normal to this plane bridge a circumferential matrix crack lying along the midplane of the specimen. Results are presented for the ene rgy release rate of this matrix crack as a function of a nondimensiona l parameter characterizing the fiber stitches. Sufficiently large valu es of this parameter ensure the applicability of the classical ACK (Av eston, Cooper and Kelly) limit for a steady-state matrix crack subject to sigma(0). The results obtained can be used to choose the level of stitching such that transverse matrix cracking will be excluded.