Abstract
Fractal branch and bound method has developed by the authors for the optimization of stacking sequences to maximize buckling load of composite structures. The method demands an approximation of a design space with a response surface comprising quadratic polynomials for pruning fractal branches of stacking sequences. The approximation of the objective function with quadratic polynomials has been confirmed for the buckling load maximizations and flutter speed limit maximizations using lamination parameters as predictors. In the present study, flutter speed maximization with a constraint of buckling load is employed as an example of stacking sequence optimizations by means of the fractal branch and bound method with a strength constraint. The present paper shows the theoretical background of the fractal branch and bound method, and approximations using quadratic polynomials with lamination parameters as predictors are performed. After that, the effectiveness of the method for the supersonic panel flutter of composite laminates is investigated using two cases. As a result, the method is successfully applied, and the practical optimal stacking sequence is obtained using modified response surfaces.
