Susceptor-assisted induction curing behaviour of a two component epoxy paste adhesive for aerospace applications

Abstract

The curing behaviour and the mechanical behaviour of susceptor-assisted induction-cured adhesively bonded joints has been investigated. Induction Heating (IH) was established by mixing Iron particles into a two component epoxy paste adhesive. The effect of different process parameters, such as particle content, coupling distance and coil current, on the IH curing process was evaluated by experimental tests and simulation of the induction heating process in COMSOL multiphysics. The process simulation showed that hysteresis losses has a major contribution for the heat generation of IH using Iron particles. Differential scanning calorimetry (DSC) analysis was used to assess the effect of susceptor particles on the cure behaviour of the adhesive. The results showed that the Iron particles do not interfere with the curing process of the epoxy adhesive in scope.The mechanical performance was evaluated through Single Lap-Shear (SLS) testing at different volume-percentages of Iron particles in combination with glass fibre reinforced plastic (GFRP) adherends. Induction-cured SLS samples were compared with conventional oven-cured SLS samples. In the oven cured samples, the addition of Iron particles resulted in a decrease in the lap-shear strength of 15% to 20%, even for a volume-percentage as low as 0.5%. An additional increase in particle content up to 7.5v% did not show any additional reduction in the lap-shear strength. Furthermore, results show that when curing the adhesive layer from the inside, as in the susceptor-assisted induction heating, the lap-shear strength is 6% higher than in oven-cured samples (curing the adhesive layer from the outside).