Simulation of Liquid Composite Moulding Processes with Deformable Tooling

Abstract

This thesis presents the development, implementation, and validation of a model and numerical simulation for Liquid Composite Moulding (LCM) processes with deformable tooling. LCM is an important and growing family of processes used to produce composite products in a variety of industries, including the automotive, marine, aerospace, and energy sectors. Its flexibility in terms of production scale, part quality, and setup cost has enabled it to supplant traditional fabrication methods for both high and low end applications. However, if this trend is to continue despite the rising complexity and scale of these applications, a more sophisticated approach to process design is needed. An important contribution in this area has been the development of process simulation tools, which find use in both academic and commercial settings. These tools enable improved and cheaper process design and troubleshooting through predictions of important parameters such as fill times, resin flow patterns, and void formation. Although all LCM processes employ closed moulds, the construction and mechanical properties of those moulds range from rigid tools to thin films. The RTM Light (LRTM) process sits between these two extremes, replacing one rigid mould half with a lightweight, semi-rigid component. The present work forms the first comprehensive treatment of flexible mould structures in LCM process simulation. A process model and numerical simulation has been developed that can accommodate rigid, semi-rigid, and fully flexible mould types within a single framework, and thus represents a generic approach to LCM process simulation with regard to mould construction. The model and simulation capture the coupled interactions between resin flow, preform deformation and mould deflection that occur prior to, during, and after the resin injection stage. From a modelling and solution perspective, RTM Light is similar to the fluid-structure interaction (FSI) class of problems, where in this case the fluid is a saturating deformable porous medium and the structure is a compliant mould. The modelling and numerical work is supplemented by an experimental study of the RTM Light process, which investigates the effect of fill mode, mould construction, and preform composition on critical processing parameters. The experimental data are in good agreement with simulated results, which suggests the approach provides accurate predictions of the behaviour in deformable tooling LCM processes, and can therefore form a sound basis for continued research and development of these processes.