Nonlinear Aeroelastic Model for a Highly Flexible Flapping Wing in Hover

This paper presents a standalone coupled aeroelastic framework for highly flexible flapping wings in hover for Micro Aerial Vehicle (MAVs) application. A realistic hover-capable flapping-wing MAV utilizes highly flexible wings operating at high frequencies/amplitudes, which causes extreme wing deflections and highly unsteady, vortical flows. The strong fluid-structure coupling and the complicated flow physics make the performance of such a system extremely difficult to predict. In the present model, in order to accurately capture the large nonlinear wing deflections, a geometrically exact shell theory has been adopted. A potential-flow-based unsteady aerodynamic model is then coupled with the fully nonlinear structural model to generate high fidelity coupled aeroelastic framework. Both the structural and aerodynamic models are validated independently before coupling. The coupling process required spatial and temporal interpolation functions for the two models to communicate with each other. An innovative flapping wing experimental setup was designed and built to measure the time-history of lift forces acting on a flexible wing during a flap cycle. The instantaneous lift force predictions from the coupled aeroelastic model is compared with the results from the in-house flapping wing experiments at moderately high frequencies.