Effects of Design Rules on the Lamination Parameters Feasible Region

The determination of lamination parameters feasible region is extremely important for design and optimization of composite structures. While the feasible region for unconstrained laminates is well-established, applying mandatory design rules alters both its size and shape. This is especially relevant in aeronautical composite structures, where design rules are quite often mandatory. However, existing studies do not specify the exact boundaries of the feasible region, which is significant since the optimum for critical loading conditions, such as buckling, often lies on or near the boundary. This work proposes an innovative approach for finding the exact feasible region with several design rules. The initial step is to generate laminate databases containing all feasible stacking sequences with the prescribed design rules, up to 36 layers. These data provide a rigorous insight into the distribution patterns. Based on this information, a simple and computationally efficient procedure, based on the exact determination of a few key boundary points, allows for the exact determination of the feasible region for any number of layers.