An Interlaminar Tensile Strength Specimen

This paper describes a technique to determine interlaminar tensile strength, σ_3c of a fiber reinforced composite material using a curved beam. The specimen was a unidirectional curved beam, bent 90°, with straight arms. Attached to each arm was a hinged loading mechanism that was held by the grips of a tension testing machine. Geometry effects of the specimen, including the effects of loading arm length, inner radius, thickness, and width, were studied. The data sets fell into two categories: low strength corresponding to a macroscopic flaw related failure and high strength corresponding to a microscopic flaw related failure. From the data available, the specimen width and loading arm length had little effect on σ_3c. The inner radius was not expected to have a significant effect on σ_3c, but this conclusion could not be confirmed because of differences in laminate quality for each curve geometry. The thicker specimens had the lowest value of σ_3c because of poor laminate quality.