Study on void formation in multi-layer woven fabrics

The presence of voids has a deleterious effect on composites mechanical properties. In this paper, two simplified unit cells for in-plane impregnation in multi-layer woven fabrics (MWFs) have been suggested. A mathematical model has been developed to describe the mechanism of void formation during RTM processes. The flow fronts and void formation in these two cells were also numerically simulated using control-volume method. The simulated results agree well with the result predicted by the mathematical model. The results show that, for a given fiber preform the ratio of weft axial permeability K-b(a) and warp transverse permeability K-b(t) is responsible for the size of void. (C) 2004 Elsevier Ltd. All rights reserved.