Mechanical sizing of a composite launcher structure by hybridizing a genetic algorithm with a local search method

The concern of this paper is the hybridization of a genetic algorithm with a local search method to optimize a sandwich composite inter stage skirt located in the upper part of a launcher structure that involves simultaneously discrete (plies orientations and thicknesses), categorical (plies and core materials) and continuous (core thickness) design variables under several mechanical and manufacturing constraints. Genetic algorithms and local searches are two complement solutions where the essential element of local searches lies in focusing the search not on the full space of solutions but on a smaller subspace defined by the solutions that are locally optimal for the given genetic algorithm optimization engine. A significant attention is paid to the implementation of the genetic and the hybrid genetic algorithms with their different mechanisms in line with this framework. Obtained results reveal that the adopted hybrid approach is highly capable of improving the performance of the solution and saving computation time. The latter is a significant achievement especially that currently there exists an important need for lighter and more resistant structures with reduced manufacturing costs.