Overview of Adaptronics in Aeronautical Applications

Abstract

The Institute of Structural Mechanics (ISM) at the German Aerospace Center is working on several aeronautical projects dealing with adaptive structures. These structures are characterized by their mul-tifunctionality, i.e. adaptronic actuator systems are structurally integrated such that they serve not only as actuators but also as loadcarrying members of the structure itself. With respect to the fail-safe prin-ciple prevalent in aircraft design, this implies that the actuator elements ought to be operated parallel to passive load-carrying structural elements, allowing not only a sensible distribution of opera-tionally induced loads on active and passive structural elements, but sufficient residual strength after a failure of the actuation function as well. Some examples will be presented at the workshop. In transonic civil transport airplanes the structural and aerodynamic efficiency of cruise flight can be increased significantly by varying the wing camber with a flexible trailing edge and building up a variable bump at the upper surface of the wing, both optimized for every flight condition during the complete mission. In order to provide an optimal gap size between wing and flap during high lift flight with flaps extended, these are actively re-deformed in spanwise direction due to the applied airload which leads to a much better high lift behavior. In high performance aircraft one example is concerned with vibrations of the vertical stabilizer due to vortexes, generated by the wings leading edge. They are reduced by means of an active interface, made of piezoceramic stack actuators, thus resulting in reduced structural loading. Present helicopter research mainly focuses on the improvement of the aerodynamic efficiency and on the reduction of vibrations and acoustic emission. The adaptive blade twist concept, developed by ISM, allows to directly control the twist of the helicopter blades by smart adaptive elements and through this to positively influence the main rotor area which is the primary source for helicopter noise and vibrations.