In Situ and Quantitative Control of Resin Transfer Moulding (rtm) Using Fibres Optic Sensors

The RTM process is mostly used in aeronautics and space industries. In this process the reinforcement is placed inside a mould and a low viscosity resin is injected and heated until it polymerises. The impregnation of the reinforcement and the polymerisation step are two keyelements to reach good piece quality. The knowledge of the front position of the thermosetting resin and polymerisation degree in the piece and associated stresses are then of crucial interest in the context of the process optimisation to avoid dry areas and to limit stresses. The filling step can be monitored by thermocouples or more recently with dielectric sensors or fibre Bragg grating. Real time measurements of dielectric permittivity or heat flux on industrial parts are already performed to estimate polymerisation degree. Finally, thermal and chemical strains are generally estimated thanks to strain sensors but the use of fibre Bragg grating is now in constant development.