Development of an optimized thermal cure cycle for a complex-shape composite part using a coupled finite element/genetic algorithm technique

The uniform curing of a complex-shape composite part can be guaranteed by implementing an optimized thermal cure cycle. An optimal cure cycle reduces the internal stresses generated during composite processing and leads to obtain a high-quality composite part in minimum processing time. In this paper, the optimal design of thermal cure cycle for the production of a complex-shape composite part made from epoxy/glass prepreg is presented. For this purpose, a complete curing optimization algorithm is proposed to minimize the temperature and cure gradients that appear during curing and cooling steps in the different areas of composite part. A complete objective function has been defined based on six sub-objective functions including maximum degree of cure, maximum temperature, cross-over at after gel point (AGP), cure gradients after AGP, temperature gradients and curing time. The variation of density, specific heat capacity and thermal conductivity with degree of cure were taken into account. The optimal thermal cure cycle was automatically designed by linking computer simulation software Abaqus and numerical optimization programs coded in Matlab software. Two different kinetic methods have been considered to determine the kinetic parameters of the curing reaction of the prepreg. The effect of kinetic models on the determination of the optimized cure cycle has been investigated.