Preliminary design of a compliant mechanism for rib morphing implementation

Adaptive structures have been individuated as a topic of great interest for researchers working in aeronautical field. This is mainly due to the several benefits which can be obtained by implementing morphing technology in aircraft design; novel structures, in perspective fully-adaptable to different flight conditions, may in fact bring many advantage at system level: from noise emission reduction to aerodynamic efficiency enhancement and fuel-burn optimization. Such an approach, in spite of related benefits, presents a challenging problem: the same structure has to be stiff enough to withstand external aerodynamic loads without appreciable deformations while being flexible enough to dramatically change its external shape. In the framework of the CRIAQ MDO505 project, the first joined program between Canadian and Italian research centers, academies and leading industries, the authors addressed the design assessment of a novel rib architecture enabling the camber variation of the aileron airfoil through a compliant mechanism. The architecture allows controlled aileron’s shape modification in order to improve the wing tip / aileron aerodynamic efficiency at low subsonic speed. On the base of specific target shapes and related external loads, the structural layout of the device was preliminarily defined. The reference geometry was tailored for a full scale wing of a civil regional transportation aircraft, where the conventional aileron component was substituted by the morphing device. Each aileron rib was composed of multiple, suitably shaped, rigid elements whose relative rotations were driven by means of an actuated linear spring. Advanced FE analyses were carried out in order to properly size the compliant mechanism and the actuation chain. System’s capability to reproduce target morphed shapes under the action of aerodynamic loads was successfully proved on the base of FE analyses outcomes.