عنوان مقاله [English]
In recent decades, flapping-wing micro aerial vehicles (FWMAVs) have shown an increased interest for flight at low Reynolds numbers. Major components of a flapping wing system are flapping mechanism and flexible wings. The degree of wing flexibility represents an important role in the production of required unsteady aerodynamic forces of flight. In the present work, a simple four-bar crank-rocker mechanism transforms the rotational motion of a small electric motor to a harmonic flapping motion. The flapping frequency is controlled directly by altering the input voltage. A flexible membrane half-elliptical planform wing with a span of 100 cm, a mass of 10 grams and an aspect ratio of 6 is developed. Furthermore, a test bed is built to investigate the aeroelastic features of a flapping wing vehicle. To extract important kinematic parameters such as relative deflection, angular velocity and acceleration, a high-speed camera facility and image processing techniques are used. Results show the total normal force has two component, the inertial force which is a function of the wing mass distribution and the flapping kinematics, and the aerodynamic force caused by the flapping motion and wing deformation. These inertial and aerodynamic forces bend and twist the wings during the flapping motion, resulting in passive shape variation that may affect many aspects of flight performance. Maximum deflection happens mostly in the zero angle position of the wing when the wing is parallel to the horizon, in this condition combination of dynamic forces are maximum as well. In addition, by using this facility, verification of aeroelastic simulations become possible.