Analysis of the vacuum infusion moulding process
This thesis focuses on flow through compliant porous media with applications to the manufacturing of composites by vacuum infusion (VI). The context of this work is the need for reliability in environmentally friendly composite processing methods for composite materials. Commercial reality and the prospective application to low cost structures for the transportation industry dictate that appropriate emphasis should be put on obtaining robust simulations, ensuring reliability and progressing toward efficient means of process control. In this context, the open mould manufacturing processes which have been used to produce large composite structures, and are not conducive to quality nor environmental responsibility, must be replaced. Hence, establishing composites as a viable alternative requires closed moulding techniques, of which VI is the most practical for large structures, but where reliability is required for economic survival. This work addresses many aspects of this problem, by making innovative use of fluid mechanics and developing, implementing and proposing new analysis and modelling tools for VI. Main results include a validated analytical model for flow through compliant media, a study of the compliance of textile reinforcements, a finite element model for VI and novel stochastic techniques for the analysis of reliability in liquid composite moulding processes. The work discussed herein stems from a thorough evaluation of published models and leads to novel flow modelling tools for VI including a unique and general formalism for textile compliance. Using these tools it was possible to study, for the first time, the effect of different parameters on VI manufacturing. The reliability issue was addressed by integrating stochastic models for compliance and permeability, and the ability to model complex geometries was demonstrated by adapting a commercial finite element flow code (LIMS).