New in-plane and interlaminar shear test methods for fiber reinforced composites

A new compact double-notched specimen for in-plane shear testing of isotropic, anisotropic and composite materials was developed. A preliminary test of the specimen was performed on a cross-ply laminate. High sensitivity moire interferometry was used to determine the shear and normal strains on the entire face of the specimen. The results of the test were compared to those of the Iosipescu specimen on the same material. The compact specimen produced a more uniform and more pure shear distribution than the Iosipescu specimen. Stiffness measurements of the composite material were made. A detailed investigation of the specimen was performed and it revealed important attributes and deficiencies of the specimen. Recommendations for future work are cited. The interlaminar shear response of a cross-ply composite was investigated. Shear strains on a ply-by-ply basis were measured using moire interferomety. Qualitative and quantitative information of the interlaminar shear characteristics of the material were obtained. The interlaminar shear modulus of individual plies and the effective modulus for the laminate were determined. Variations of nominally equal plies were observed.