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 degrees, 90 degrees, +/- 45 degrees. However, studies have shown that an expanded set of ply orientations may lead to more efficient structures for specific problems. in particular, 601 plies are optimum for shear in buckling for long anisotropic composite laminated plates. A two-level optimization approach, using 0 degrees, 90 degrees, +/- 45 degrees, +/- 30 degrees, +/- 60 degrees 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. (C) 2009 Elsevier Ltd. All rights reserved.