IMPROVED GENETIC ALGORITHM FOR THE DESIGN OF STIFFENED COMPOSITE PANELS

The design of composite structures against buckling presents two major challenges to the designer. First, the problem of laminate stacking s equence design is discrete in nature, involving a small set of fiber o rientations, which complicates the solution process. Therefore, the de sign of the stacking sequence is a combinatorial optimization problem which is suitable for genetic algorithms. Second, many local optima wi th comparable performance may be found. Most optimization algorithms f ind only a single optimum, while often a designer would want to obtain all the local optima with performance close to the global optimum. Ge netic algorithms can easily find many near optimal solutions. However, they usually require very large computational costs. Previous work by the authors on the use of genetic algorithms for designing stiffened composite panels revealed both the above strength and weakness of the genetic algorithm. The present paper suggests several changes to the b asic genetic algorithm developed previously, and demonstrates reduced computational cost and increased reliability of the algorithm due to t hese changes. Additionally, for a stiffened composite panel considered in this study, we present designs lighter by about 4% compared to pre viously obtained results.