Morphing wing flexible skins with curvilinear fiber composites

Morphing aircraft wing skins require composites with conflicting structural requirements: low in-plane stiffness and high out-of-plane bending stiffness. In this study, composites with curvilinear fiber paths are examined to enhance these conflicting structural requirements. The numerical results show that curved fiber paths can minimize the in-plane stiffness and increase the bending stiffness simultaneously compared to a baseline plate with straight fibers. A flexibility ratio is defined to assess the in-plane and out-of-plane deformation of the plate, simultaneously. A multi-objective optimization is formulated to find optimal curved fiber paths which maximize the flexibility ratio of the morphing wing skin. The optimization is performed with fiber paths represented as independent discrete fibers and continuous curvilinear fibers. The results show a significant increase in the flexibility ratio compared to a baseline plate with straight fibers. The aspect ratio of plate, laminate stacking sequence and in-plane loading direction have considerable influence on the optimal paths of the curved fibers. (C) 2012 Elsevier Ltd. All rights reserved.