Preliminary design of a mechanism for flapping flight - Durability analysis and vibration modes

The object of the paper is the kinematic and structural design of a flapping wing UAV, in order to develop an Unmanned Aerial Vehicle, a drone capable of executing reconnaissance and videosurveillance missions. To define the characteristic dimensions of the vehicle a biological study was initially carried out, analyzing, for example, the weight-wingspan ratio for the correct kinematics of the flight. On the other hand, several mechanisms apt to reproduce flapping flight were analyzed, searching for the best solution in terms of wings' articulation. Then, an optimization of the length of the different parts of the mechanism was needed to reproduce the kinematic law, provided by CFD (computational fluid dynamics) simulations. The results of the optimization were the starting point for the design of the mechanism parts and for the diagnostic aspects. The stress resistance of the mechanical parts and fatigue life were verified in a FEM environment developing several simulations of the working conditions of the wing mechanism.