Topology optimization method of facesheet-to-skeleton connection area’s distribution design for alleviating strain concentration of flexible skins

During the morphing of flexible skins, local strain concentration may occur in the face-sheet due to different bonding methods between the face-sheet and the skeleton. To overcome this problem, we propose a strategy to improve the uniformity of the strain distribution through rationally distributing the connection areas between the face-sheet and skeleton of the sandwich-flexible-skin, and develop a topology optimization method for determining the optimal distribution of the connection areas. In this method, the connection areas between the face-sheet and the support skeleton are considered as the virtual adhesion layer comprising of adhesion materials. Based on the topology optimization idea, the distribution of connection areas is described by allocating the presence and absence of the adhesion material. The optimization model is established with minimizing the globe stress of the face-sheet as the objective function, the volume fraction of the design domain as the constraint. The effectiveness of the proposed method is verified through examples involving tensile and rotational states of the sandwich-flexible-skin with Ω-shaped honeycomb structure, and the results show that the optimization method can significantly improve the strain distribution of the face-sheet. Finally, a variable-sweep structure for unmanned aerial vehicles (UAVs) is designed to explore the practical value of the proposed method.