Stacking sequence optimization
- 「Fractal Branch and Bound Method」
In the present study, a mechanism of fractal pattern of feasible laminates in lamination parameter coordinates is discussed in detail, and a new improved stacking-sequence optimization method is proposed for complicated structures that include both in-plane and out-of-plane lamination parameters. The new method employs a branchand- boundmethod for the optimizations of stacking sequences. For the estimationof the fractal branch of stacking sequences, the new method requires approximationof the objective function of the optimizations with a quadratic polynomialusing both in-plane and out-of-plane lamination parameters. The new method is applied to a stackingsequence optimization problem of a maximization of buckling load of a hat-type stiffener structure. The method gives successfully optimal stacking sequences in an excellently short CPU time.Yoshiyasu Hirano, Akira Todoroki, Advanced Composite Materials, 13,2,(2004)pp.89-107
Yoshiyasu Hirano, Akira Todoroki,JSME Int. J.,Series A，Vol.48，No.2, (2005),pp.65-72
- 「Stacking-sequence optimization using fractal branch-and-bound method for unsymmetrical laminates」
The fractal branch-and-bound method has been developed by the authors for stacking-sequence optimizations of symmetric and balanced composite laminates comprise of two in-plane and two out-of-plane lamination parameters. Cylindrical structures such as tanks or pipes, however, are usually made from balanced laminates. In the present study, therefore, we focus on the stacking-sequence optimizations of unsymmetrical composite laminates. In the unsymmetrical laminates, nine lamination parameters including three couplinglamination parameters exist, and its feasible design region of fractal pattern is unrevealed. The paper clarifies the feasible region in which the in-plane, out-of-plane and coupling lamination parameters create fractal patterns of tetrahedrons or tetradecahedrons. Using the fractal patterns of lamination parameters, the improved fractal branch-and-bound method is proposed for unsymmetrical laminates including coupling lamination parameters. This new method is applied to stacking-sequence optimization problems of maximization of buckling load of cylindrical laminated shells. As a result, the method is successfully applied, and a practical optimal stacking sequence is obtained with low computational cost.