Synthesis of optimal control for curing the shell-like composite structures at the autoclave processing

The paper study a problem of optimal control synthesis for curing the shell-like composite structure using open die molding in autoclave. The needful control should eliminate early hard skin formation, an emergence of resin-rich or resin-dry areas, insufficient consolidation, and uneven cure. This purpose can be achieved providing the uniform distributions of temperature and degree of cure within the cured part volume. The used approach which includes the cure problem formulation, its finite element implementation, where the correct timing of heating-up and isothermal holds should be found by the optimization procedure, is illustrated on the example of shell-like composite part manufactured by two stages curing in autoclave. The control synthesis problem is formulated as multi-objective optimization problem where minimized objectives are the deviations of temperature and degree of cure within a cured part at the constraints imposed by thermal-kinetics properties of pre-preg and the manufacturing requirements. The Pareto-based optimization procedure and means of its results visualization allow to estimate the best achievable quality of manufactured composite parts, to find the satisfactory parameters of control law, and decision-making considering all imposed constraints.