Application of a genetic algorithm to optimal lay-up of shells made of composite laminates

The orientation of fiber direction in layers and the number of layers of composites play the major role in determining the strength and stiffness. Thus, the basic design problem is to determine the optimum stacking sequence of the composite laminate. Many methods are available at present for the design optimization of structural systems. However, these methods are based on mathematical programming techniques involving the gradient search and the direct search. These methods assume that the variables are continuous. In this paper, a different search and optimization algorithm, known as a Genetic Algorithm (GA), has been successfully applied to obtain the optimum fiber orientation of multilayered shells, which considers the angle of fiber orientation as a discrete variable. The principle of GA is applied to obtain optimum layers and the orientation of fibers of stiffened shells for both the symmetric and antisymmetric orientations of fibers for dynamic analysis. Shells composed of two to nine layers without stiffeners, with one stiffener, and with two stiffeners for a single as well as different materials are analyzed and the maximum frequency for each population is computed using the FEAST-C software. Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000). Published in Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 271–278, March–April, 2000.