NOVEL FLEXIBLE TOOLING TO ENHANCE LIQUID RESIN INFUSION MANUF-ACTURE FOR NET-SHAPED PREFORMS

Interest in complex textile composite materials is driven by the cost of manufacturing as Liquid Resin Infusion (LRI) processes have the potential to be significantly cheaper than conventional processes. Yet the complexity of 3D braided preforms demands novel manufacturing approaches, and this is currently achieved using inflexible and specialised processes that are capital intensive. For instance, each preform requires its own tool that is incompatible with other preforms as they may exhibit different deformation characteristics. To date such limits have acted as inhibitors to wider industrial uptake of the techniques. To reduce the cost burden and improve flexibility constraints flexible tooling for LRI has long been desired. But a fundamental problem in this approach is the dimensional stability of the complex preforms and components that can lead to defective features such as inhomogeneous thickness distribution in convex corners, and resin rich zones formed in under-consolidated areas. The primary reason for these features is insufficient tooling constraints and this paper suggests an intermediate rigid/flexible solution, which does not require a complete redesign of costly tooling when changing preforms. The novel tooling solution is realised by the conversion of an existing prepreg-based toolset into a fully capable mould with flexible inserts, and complex 3D braided net-shaped architectures with various constraints are tested. Infusion trials incorporate the novel flexible tooling processes as well as some infused material quality analysis that includes measurements of the macro dimensions and a wide range of internal features such as pores, fibre volume fraction distribution, and internal geometry. Results show promise and further work is identified.