Multi-objective optimal design of laminated composite skirt using hybrid NSGA

Abstract

In this paper a new hybridised version of non-dominated sorting genetic algorithm (NSGA) is proposed to solve combinatorial optimisation problems associated with laminated composite structures. The proposed algorithm is used to optimise the design of hybrid laminated fibre composite skirt of solid rocket motor, subjected to a buckling strength constraint and an overstressing strength constraint under aerodynamic torque and axial thrust. The present investigations involve in determining the best laminate configuration to minimise the weight as well as cost of the skirt through multi-objective optimisation. Buckling strength and overstressing strength of the composite cylindrical skirt are analysed using classical laminate theory. Tsai-Wu failure criterion is employed to assess the first ply failure, and failure strength is described by an overstressing load level factor. The superiority of the proposed hybrid algorithm is demonstrated by comparing with the originally proposed NSGA algorithm. The studies presented in this paper clearly indicate that the proposed modification to the NSGA improves the convergence properties quite appreciably.