SIMULATIVE CURE OPTIMISATION OF THICK AND ULTRA-THICK LAMINATES USING MULTIPLE EPOXY RESIN SYSTEMS

The exothermic cure reaction of epoxy can lead to temperature overshoots within thick fibrereinforced laminates, resulting in uneven cure and high cure gradients. These gradients can cause increased residual stresses and lower the mechanical properties of the manufactured part. In literature, various attempts to mitigate the impact of generated heat are presented, including active cooling and the use of multi-dwell temperature profiles for cure. This paper presents a study on the effects of using two different accelerator concentrations in the inner and outer layers of 25 mm, 50 mm and 100 mm thick laminates on temperature overshoot, process time and cure gradient. A multi-objective optimisation algorithm in conjunction with a finite element method (FEM) simulation model was employed to optimise the two accelerator concentrations and the temperature profile employed for the cure. While the strategy yielded no benefits for the 25 mm laminate, it was discovered that the utilisation of two distinct accelerator concentrations exerts a positive influence on temperature overshoot, process time and cure gradient for laminates exceeding 50 mm in thickness