| Resumo : |
Since the middle of last century, the use of composite structures has increased in the aerospace industry. The process of defining efficient structure laminate is still a challenge even with the processing power of modern computers. At the same time, the competitive aeronautical industry demands an efficient way for defining the ideal structure stiffness associated with specific requirements. Throughout the past decades, the scientific academy evolved its knowledge and strategy to design orthotropic laminates. The formulation and use of lamination parameters in optimizations has shown to be a good alternative to local minimum problems. In this work, the use of lamination parameters is used to define the stiffness matrix of specially orthotropic laminates. Equally, an interpolation strategy is implemented as a manner to reduce the number of design variables within the process of an structural optimization. At this manner, it is possible to avoid the local minimum problem of non-convex objective functions and, at the same time, reduce the number of design variables associated with optimizing complex structures. To investigate the efficiency of the proposed, a two step optimization process is suggested. Firstly, the material stiffness matrix of the wing plate elements are going to be optimized through lamination parameters formulation, while restricting its feasible region with Grenestedt and Gudmundson (1993) approach. At this first stage, the objective is to maximize the wing load multiplier in a linear buckling problem. Later, a size optimization is going to be performed in order to minimize the wing total weight while constraining for wing buckling. |