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A multi-objective deterministic hybrid algorithm (MODHA) is introduced for efficient simulation-based design optimization. The global exploration capability of multi-objective deterministic particle swarm optimization (MODPSO) is combined with the local search accuracy of a derivative-free multi-objective (DFMO) line search method. Six MODHA formulations are discussed, based on two MODPSO formulations and three DFMO activation criteria. Forty-five analytical test problems are solved, with two/three objectives and one to twelve variables. The performance is evaluated by two multi-objective metrics. The most promising formulations are finally applied to the hull-form optimization of a high-speed catamaran in realistic ocean conditions and compared to MODPSO and DFMO, showing promising results.

In the present work we address the problem of the dynamic response of fluid-filled shell structure in uniform translation within a compressible medium in which an acoustic source is present. This represents an important engineering problem (as for instance the noise inside the fuselage generated by an outer source of noise), which involves the interaction of the structure with both the internal and the external fluid. Specifically, a unified finite-state formulation for the integrated analysis of the complete acoustoaeroelastic problem is presented; for the lack of space, only the theoretical formulation is presented. The formulation used here represents a blend of classical modal analysis with BEM. An eigenfunction expansion is introduced for the solution of the internal acoustics and the structural dynamics. The application of BEM is twofold. First, a boundary integral formulation for the external potential flow is given. Such a formulation is based on that of Morino [9], and is solved numerically by means of a boundary element method. On the other hand, the boundary element method is used also for the determination of the acoustic natural modes of vibration of the resonant cavity, for all those cases in which no analytical expressions of the eigenfunctions are avalaible. This methodology makes possible the analysis of cavities with arbitrary geometries.