Relating Local Permeability Changes to the Deformation of Preforms during the Manufacture of Complex-Shaped Composite Structures

The transition to using carbon-fibre composites in the primary structure of passenger aircraft is now well established with focus shifting towards reducing manufacturing costs. This study reports on initial results in the development of accurate numerical process modelling tools for resin-infused composite structures. A continuum-based, finite element material model has been developed to simulate the draping of a dry carbon fibre fabric, accurately tracking the changes in the warp and weft fibre orientations. A multiple ply draping example demonstrates the large variation of shear angles that are prevalent in forming processes. The relationship between shear angle and permeability was studied experimentally as it is integral to the accuracy of the resin infusion modelling process. The anisotropic permeability of the plain weave fabric was observed to increase by a factor of five as the shear locking angle was approached, with principal permeability values, K1 and K2, increasing and decreasing by a factor of approximately two, respectively.