Abstract
Fiber/matrix interfacial crack propagation behavior was investigated by using a micro model composite specimen. The model composite specimen consists of two fibers bonded by matrix resin, and an interfacial crack can propagate without resin fracture in this specimen. Model composite specimens with an initial crack were successfully fabricated from glass fibers of about 10〜15μm in diameter and vinyl ester resin or unsaturated polyester resin. Crack propagation tests were carried out by the DCB method for model. The crack propagation tests were also conducted by using another model composite specimen with four parallel fibers distributed in a square array in the cross section. Crack propagation of four-fibers model composites is a combination of interfacial debonding and matrix fracture. Using the interfacial fracture toughness, G_i, the fracture toughness of four-fibers model composites, G_c, and the fracture surface ratio of fiber/matrix debonding in four-fibers model composites, γ_i, the fracture toughness of matrix resin, G_m was estimated on the basis of the rule of mixture, G_c= G_<iγi>+G_m(1-γ_i).
