Temperature Distribution and Curing Behaviour of Carbon Fibre/ Epoxy Composite during Vacuum Assisted Resin Infusion Moulding Using Rapid Heating Methods

Abstract

This paper designs two kinds of rapid heating methods for vacuum assisted resin infusion moulding (VARIM) process aiming to reduce the cycle time of carbon fibre/rapid curing epoxy composite fabrication. One utilizes the silicone rubber heating sheet containing thin resistance wires, and the other takes advantage of carbon fibre conductivity to produce internal resistive heating. Conventional oven heating VARIM was performed as a reference. The heating rates and temperature distributions in carbon fibre preform heated by the three heating methods with and without epoxy resin injection were investigated and compared. The curing degree and glass transition temperature of laminates fabricated by different VARIM processes were determined. The heating rate of silicone rubber heating sheet was 26 °C/min, while the carbon fibre internal resistive heating reached 30 °C/ min, which was much higher than the heating rate of 2 °C/min in oven. Unlike the highly uniform temperature distribution in the oven heating process, there was a slight temperature gradient within 5 °C in the silicone rubber heating process and a relatively large gradient within 13 °C in internal resistive heating process for dry fibre preform. When epoxy resin was injected, the temperature gradients obviously increased along the resin flowing direction especially for the rapid heating methods. However, the temperature gradient seemed not to affect the curing degree and its uniformity of laminates for all studied VARIM processes. The cycle time of composite fabrication by the rapid heating VARIM processes was reduced by over 40% compared to oven heating VARIM.