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The layup optimization for maximizing buckling loads of long laminated composite cylindrical shells subjected to combinations of axial compression, external lateral pressure, and torsion is carried out on the basis of Flügge's theory. The layer angles, that is, fiber orientation angles, of the laminated composite cylindrical shells are restricted to the values of 0, 45, −45, and 90 deg, and then nine lamination parameters are used as design variables for the layup optimization. Explicit expressions relating the nine lamination parameters are derived and used to describe the feasible region in the design space of lamination parameters. Thus, the layup optimization problem becomes a constrained nonlinear optimization problem, and the optimum lamination parameters are determined by a mathematical programming method. The laminate configurations aiming to realize the optimum lamination parameters are obtained by analytic formulas or by an unconstrained optimization procedure. It is observed that, for the laminated composite cylindrical shells with the layer angles restricted to the values of 0, 45, −45, and 90 deg, the optimum buckling loads are less than 10% lower than the optimum buckling loads obtained for unrestricted laminate configurations. [ABSTRACT FROM AUTHOR]

The flexural characteristics and layup optimization of laminated composite plates are examined in environmental conditions of temperature and moisture. The deflection of laminated composite plates is analyzed in the design space of 12 lamination parameters. The layup optimization for minimizing the deflection of laminated composite plates is carried out using all 12 lamination parameters as design variables. Mathematical programming methods are used for optimization. In hygrothermal conditions, the maximum deflection of laminated composite plates with in-plane hygrothermal stresses can be reduced by optimized nonsymmetric laminate configurations. [ABSTRACT FROM AUTHOR]

The buckling characteristics and layup optimization of long laminated composite cylindrical shells subjected to combined loads of axial compression and torsion are examined on the basis of Flu¨gge’s theory. In the buckling analysis of long laminated composite cylindrical shells, 12 lamination parameters are introduced and used as design variables for layup optimization. Applying a variational approach, the feasible region in the design space of the 12 lamination parameters is numerically obtained. The buckling characteristics are discussed in the design space of the 12 lamination parameters. In the layup optimization, the optimum lamination parameters for maximizing the buckling loads and the laminate configurations for realizing the optimum lamination parameters are determined by mathematical programming methods. It is found that in case of combined loads of axial compression and torsion, the optimum laminate configurations are unsymmetric. [Copyright &y& Elsevier]

Presents a method for determining the feasible region in general design space of a number of lamination parameters. Overview of lamination theory; Stiffness characteristics and lamination parameters; Feasible region in design space of lamination parameters.