Mechanical Behavior for 3-D Orthogonal Woven E-Glass/Epoxy Composites

Abstract

A testing program is conducted to investigate the mechanical properties and failure mechanism for 3-D orthogonal woven E-glass/epoxy composite materials, which were manufactured using E-glass for fiber and Ciba-Geigy GY260 epoxy for matrix. For the mechanical property, the testing results indicate that at the loading range of 0 to 4 KN, the inplane Young’s modulus and Poisson’s ratio obtained using the strains recorded on the matrix surfaces are close to those recorded on the filler yarn surfaces. However, for the in-plane shear modulus, the difference between data from these two surfaces is obvious. The average elastic constants from the tests compare favorably with the predicted results using the laminate block model developed previously [1]. For the tensile failure strength, there is a reasonably good agreement between the measured and predicted results using the rule of mixture. Observation of the specimen fracture surfaces reveals that for a specimen cut along the x or y direction, its fracture surface is generally perpendicular to the applied loading direction. However, for a specimen cut along the 45° with respect to the stuffer yarn direction, the fracture surface is generally parallel to the stuffer yarn. The larger pullout lengths for the failure yarns are obviously observed from the specimen fracture surfaces, but yarn pullouts were not observed for the 3-D orthogonal woven CFRP composites [2].