Optimization design process of a morphing winglet

Aeronautic and aerospace engineering is recently moving in the direction of developing morphing wing devices, with the aim of making adaptable the aerodynamic shapes to different operational conditions. Those devices may be classified according to two different conceptual architectures: kinematic or compliant systems. Both of them embed within their body all the active components (actuators and sensors), necessary to their operations. In the first case, the geometry variation is achieved through an augmented classical mechanism, while in the second case the form modification is due to a special arrangement of the inner structure creating a distributed elastic hinges arrangement. Whatever is the choice, novel design schemes are introduced. Then, it is almost trivial to conclude that standard methods and techniques cannot be applied easily to these innovative layouts. In other words, because new architectures are produced, the former construction paradigms cannot be maintained as they are but shall be somehow transformed and assimilated by the design engineers’ community. In the meantime, the realization process should go on and morphing elements shall be realized, irrespectively of the full maturity of the associated concepts. Therefore, if optimization methods are important for the better exploitation of usual constructions, they become absolutely necessary for the technological demonstration of the capability of such breakthrough systems. In fact, standing their aim of improving the effectiveness of the aircraft flight and reducing then its overall weight, mass impact plays a fundamental role. Promised benefits could completely vanish if the added should overcome the saved weight! In the study herein presented, the design process of a morphing winglet is reported. The research is collocated within the Clean Sky 2 Regional Aircraft IADP, a large European programme targeting the development of novel technologies for the next generation regional aircraft. The ultimate scope concerns the definition of an adaptive system for alleviating the gust loads and possibly modifying the wing load distribution in the sense of minimizing the attachment momentum (the parameter that governs the wing sizing). The proposed kinematic system is characterized by movable surfaces, each with its own domain authority, sustained by a winglet skeleton and completely integrated with a devoted actuation system. Preliminary aeroelastic investigations did already establish the robustness of the referred structural layout. This paper summarizes the activities relating to the optimization of the envisaged morphing system architecture. Moving from a standard configuration, a process is carried out to identify the lighter adaptive layout that can bear the external and internal loads without experiencing excessive stress levels for its safe operation. The most severe loads are taken into account for this process, as provided by the industrial partner, showing the reliability of the proposed solution on-board of a standard commercial aircraft. The optimization process produces interesting, sometime surprising, results that promise to reduce the weight impact of the structural skeleton for more than 40% with exclusive reference to the regions undergoing the optimization process. Such figure reduces to 15% if the complete structure is taken into account, and 12% if the skin contribution is included. The innovative outcomes are discussed in detail. Results are verified with a dedicated study that proves the consistency of the procedure and the trustworthiness of the computations.