Finite element modelling of 3D woven composites for stiffness prediction

As interest in the use of composite materials for structural applications continues to increase, alternative reinforcements to conventional pre-preg systems are being more widely considered. 3-D woven composites are gaining increased prominence due to their ability to produce near net shape preforms as well as integrated third direction reinforcement. The important characteristics of 3-D woven preforms that make them suitable for composites are high axial rigidity, flexibility, formability and stability. One of the barriers to their advancement and increased use is the difficulties associated with creating numerical models to predict their performance. This is predominantly due to the complexity of the internal architectures which result in large finite element models and produce highly degenerated inter-tow regions which are difficult to mesh. Due to the almost infinite possibilities for variation in architecture created by the weaving process, it is highly desirable to have a predictive capability to reduce physical testing and aid design. In this paper a method for predicting the stiffness of two characteristic 3D woven architecture styles is presented and compared to experimental data where available.