Stacking sequence optimization of a composite cylindrical shell for vibrations by hybrid continuous optimization

In this paper, stacking sequence optimization of a laminated cylindrical shell for obtaining maximum natural frequency has been studied. The anisotropic cylindrical shell has finite length with simply supported conditions at both ends. Three-dimensional elasticity approaches are used to obtain the objective function. To perform optimization, a hybrid method, combining Tabu search (TS) and simplex search (SS) is used. TS allows the solution space to be widely covered. To stimulate the search towards solutions far from the current one, and to avoid the risk of being trapped into a local maximum, SS is used to accelerate the convergence towards a maximum. The Nelder—Mead simplex algorithm is a powerful classic local descent algorithm that does not use the objective function derivative. Therefore, the exploration is performed with a TS and then exploitation is done with a Nelder—Mead SS. Finally, in the numerical results, the efficiency of this combined approach has been demonstrated for a multi-layered composite cylindrical shell and compared with the pure global method.