Vacuum infusion of polymer composites

Sammanfattning: The current trend towards an increased use of vacuum infusion for manufacturing of high performance fibre reinforced polymer composites has stressed the necessity of an advanced modelling of the process. Until recent years development in this area has mainly been based on trial and error and the behaviour of the method is therefore not fully understood. The basic principle of the vacuum infusion process is that a stack of dry fabrics is placed between a stiff mould half and a flexible and airtight bag. The bag is sealed to the mould expect at certain positions being open for resin supplies and outlets. Liquid resin then penetrates the stack by a reduction of the pressure at one or several positions in the formed cavity. After complete filling the pressure in the cavity is evened out by retaining the vacuum level at the outlets throughout curing of the resin. The overall goal of this research is to develop tools that ensure optimum and secure processing in practical work with vacuum infusion. The means to achieve this goal has so far been industry scale experiments, simple analysis and numerical simulations. The experimental part comprises full-scale impregnations where thickness variations are measured with an advanced optical metrology system and the out-of-plane flow front is monitored by means of colour marks in the reinforcement stack. Experimental findings are then incorporated in a numerical model including moving boundaries and two-phase flow through porous media based on a commercial software for computational fluid dynamics.