Predicting mechanical properties of thin woven carbon fiber reinforced laminates

Abstract

While plain woven composite has been widely used over decades most studies are limited to predicting in-plane properties of multi-layer laminates or overall response of single-layer composites. Deployable space applications require them to be ultra-thin and hence generally made of one to six layers of thin-woven composites where out-of-plane behavior is dominant. Classical lamination theory over predicts the out-of-plane stiffness when they are made of one to two layers and relative positioning of each layer can have a significant effect on predictions for two-layer composites. This paper focuses on predicting micro-mechanical behavior of two-ply plain weave laminates under small strains. A representative volume element and its properties are obtained through micrographs to develop a homogenised Kirchohoff plate model for predicting constitutive relationship in the form of a six by six stiffness matrix. Effect of different idealization of cross-sectional and weave profiles are examined using five different tow models and the predictions are validated against experimental results obtained from uni-axial tension and four-point bending tests performed on 0/90 and 45 laminates. Further it is shown that relative positioning of plies influences both axial stiffness and bending stiffness of the laminate.