Active Aeroelastic Tailoring of High-Aspect-Ratio Composite Wings

Abstract

This paper presents a framework for studying the effects of combined bending and twisting actuation on the aeroelastic performance of highly-flexible active composite wings. The effects of embedded anisotropic piezoelectric strain actuators are consistently accounted for throughout the nonlinear aeroelastic analysis. The nonlinear active aeroelastic analysis consists of an asymptotically correct active crosssectional formulation, geometrically-exact mixed formulation for dynamics of moving beams, and a finitestate unsteady aerodynamics with the ability to model dynamic stall using the ONERA model. Once the nonlinear equilibrium is determined, a linearization about that point yields a set of equations in state space form. From that, different LQG controllers can be designed and the closed-loop system simulated to determine the impact of the anisotropic piezoelectric strain actuators on the stability enhancement and gust alleviation characteristics of flexible wings. A proposed wind tunnel model is presented to illustrate the analysis framework and to show the potential of active aeroelastic tailoring using active fiber composites. Results show that the orientation of the actuators and the electric field profile can be tailored for maximum stability augmentation or for maximum gust alleviation, and that a compromised situation can still have significant improvement in both performance metrics.

The effect of elastic couplings and material uncertainties on the flutter of composite high aspect ratio wings

“…Baets et al [28] looked at the aeroelastic behaviour and flutter speed sensitivity of composite spar-box wings with root flexibility; they observed that wing's root flexibility significantly affects its stability and can change both flutter and divergence speeds. The effect of combined twisting and bending actuation on the aeroelasticity of composite high aspect ratio wings has been investigated by Cesnik et al [29] where the nonlinear aeroelastic response of the wing with embedded anisotropic piezoelectric actuators was considered. They concluded that the orientation of the actuators has the tailoring effect on the stability of the wing.…”

Active Warping Control of a Joined Wing/Tail Airplane Configuration

“…If the conventional design paradigm is to be used, the wing flexibility has to be counteracted by additional structural reinforcements that will result in extra mass penalty. Some basic studies exploring APA for active aeroelastic tailoring of such vehicles 4 show that multiple objectives can be achieved by the same wing realization. Studies were conducted for flutter boundary enhancement and gust load response.…”

Nonlinear Aeroelastic Simulation of X-HALE: a Very Flexible UAV

“…With the focus on a reduced number of states to represent the complex nonlinear problem, the framework, named the University of Michigan's Nonlinear Aeroelastic Simulation Toolbox (UM/NAST), provides a suitable plant representation for control design. Several aeroelastic issues in high-altitude long-endurance aircraft have been addressed, including nonlinear aeroelastic modeling 9,11 , integral wing actuation for generating maneuver loads 17,18 , flutter boundary enhancement 19 , gust load alleviation 20 , and overall nonlinear vehicle optimization of unconventional configurations 17 .…”