Genetic optimization of two-material composite laminates

This paper describes the optimization of a composite laminate made from two materials. The use of two materials in the laminates design can offer improved designs, as it is possible to combine the desirable properties of the two materials. In this paper, we consider the use of graphite-epoxy, which has high stiffness properties, but is expensive, and glass-epoxy, which is not as stiff, but has a much lower cost. The multi-material composite optimization gives rise to a multi-objective optimization problem because weight and cost have to be minimized simultaneously. This requires the construction of a Pareto trade-off curve, which is done here by solving a series of optimization problems with different convex combinations of the two objectives. For each problem, the selection of material and ply orientations is performed using a genetic algorithm. An example of the design of a plate subject to a constraint on its first natural frequency is used to demonstrate the approach.