Enhanced two-level optimization of anisotropic laminated composite plates with strength and buckling constraints

In laminated composite design, ply orientations are often restricted to 0°, 90°, ±45°. However, studies have shown that an expanded set of ply orientations may lead to more efficient structures for specific problems. In particular, 60° plies are optimum for shear in buckling for long anisotropic composite laminated plates. A two-level optimization approach, using 0°, 90°, ±45°, ±30°, ±60° plies, is presented. At the first level, lamination parameters and plate thicknesses are used to minimize the mass of the composite plate subject to strength and buckling constraints. At the second level, a new modified particle swarm is used to determine laminate stacking sequences. It is shown that mass savings of up to 7.2% can be achieved and that the modified particle swarm outperforms the standard particle swarm in terms of quality of design and efficiency.