Multiaxis 3D Woven Preform and Properties of Multiaxis 3D Woven and 3D Orthogonal Woven Carbon/Epoxy Composites

In this study, multiaxis 3D woven preform was developed with five yarn sets: + bias, -bias, warp, filling, and z-yarns. The orientation of the yarns on the five axis have improved the mechanical properties of the preform. The yarns of the preforms, which were made of polyacrylonitrile (PAN)-based carbon fibers, were consolidated with an epoxy resin. These preforms were tested and compared with the 3D orthogonal woven carbon composites. It was found that in-plane shear strength and modulus of multiaxis 3D woven composite were higher than that of the 3D orthogonal woven composite. However the bending strength, bending modulus, and the interlaminar shear strength of the multiaxis 3D woven composite were slightly lower than that of the 3D orthogonal woven composite because of the orientations of +/-bias yarns on both surfaces of the multiaxis 3D woven structure. The failures of both woven samples were also analyzed for the assessment of their mechanical behaviors. The unit cell of the multiaxis 3D woven preform was described. Depending on the unit cell geometry, some relationships were developed to predict the volume fraction of each yarn set in the preform and these predicted results were also compared with the measured values.