Performance evaluation and modeling of braided composites

Braided composites have good properties in mutually orthogonal directions; more balanced properties than unidirectional laminates and have better impact resistance. These composites are being considered as a primary load carrying components in place of conventional laminated composites. They are being manufactured by using new process such as Vacuum Assisted Resin Transfer Molding (VARTM). This new process is a low cost, affordable and suitable for high volume manufacturing environment. In VARTM process, the flow of resin occurs in-plane as well as in the transverse directions to the preform. The permeability of the preform, fiber architecture and fabric crimp has an influence on the wetting of the fabric. This paper addresses a detailed study of VARTM manufactured 2x2 biaxial braided composites. These composites are fabricated using AS4 carbon fibers and vinyl ester resin system components. These braided composites are being evaluated for structural applications. To assess the feasibility of this material manufactured through VARTM, it is very important to understand the tensile behavior of these composite materials. Numbers of tests are performed to evaluate the basic properties such as modulus, ultimate tensile strength, and Poisson's ratio of VARTM manufactured braided composites. This paper also presents, a finite element model for the 2 x 2 biaxial braided composites to predict the mechanical properties. © 2003 The American Institute of Aeronautics and Astronautics Inc. All rights reserved.