The design and fabrication of 3D multi-layer woven T-section reinforcements

The main objective of this paper is to assess the effect of through-the-thickness reinforcement on the in-plane strength of composite T-shaped specimens, woven on conventional weaving apparatus, and to compare these with a similar 2D laminated composite. The design and fabrication of multilayer woven structures where yarns are orientated in three mutually perpendicular axes are outlined, and a comparison of such structures with a conventional 12 layer laminated composite is shown. Three-dimensionally reinforced T-sections are processed with and without resin-rich areas to show the effect of the through-the-thickness reinforcement at the interface where the web divides equally to form the flanges. A range of six-layer woven T-section reinforcements were designed specifically to overcome the problems of resin-rich areas at the web/flange interface. In-plane strength tests were carried out on the composite and microscopic analysis of cross-sections was undertaken in an attempt to verify yarn paths within the reinforcement structure and to assess the deformation of yarns during the composite forming process. The results indicate that the type and amount of interlinking influence the mode of failure but their relationship with in-plane strength is complex.