A numerical study examining the formation of consolidation induced defects in dry textile composites

A key factor in the performance of composite materials is the quality of the final manufactured part. Regardless of the material form or process there are two common steps to produce this; the forming of an initially planar material into a three-dimensional shape and the consolidation of the material to achieve the required thickness and fibre volume fraction. During these processes the material is required to deform to achieve the final geometry. Defects which are induced by these processes can severely degrade the performance of the final structure. While a large body of research has been dedicated to understanding and modelling forming induced defects, consolidation induced defects have gone relatively unexplored. In this paper a simple approach is introduced to include the high transverse compliance of textile materials into conventional forming simulations, using 2-d finite elements, so that consolidation induced defects during forming can be analysed. This approach allows for the high stiffness of the fibre direction, non-linear shear stiffness, out-of-plane bending stiffness and through thickness compressibility of textiles to be fully present within the model. Using this approach, the consolidation of a large numbers of plies over curved tooling is simulated to examine the various parameters that contribute to the formation of defects.