Abstract
Structural optimization considering stiffener layout has continuous and discrete variables. It is difficult for GA to deal with continuous variable. In order to solve this problem, Hybrid GA made from GA and optimization method being strong in continuous variables is used. This study suggests the optimization method combined GA. The optimization method determines position of stiffener and plate thickness and reduces calculate cost. This structural optimization problem assumes plate thickness constraint. The objective function is minimization of the square of mass of the structure. Updating plate thickness uses displacement formula of plate bending. Updating span uses updating vector of span gotten by searching relation between a change of span and a change of objective function. The updating vector of span similar to gradient vector of steepest decent method. Suggested optimization method is verified by a sample problem. The result of optimization is satisfied the constraint condition. Stiffeners are allocated at regular intervals. As a result, attached stiffeners properly by this method are confirmed.
