Flutter of Telescopic Span Morphing Wings

Abstract

This paper studies the aeroelastic behavior of telescopic, multi-segment, span morphing wings. The wing is modeled as a linear, multi-segment, stepped, cantilever Euler–Bernoulli beam. It consists of three segments along the axis and each segment has different geometric, mechanical, and inertial properties. The aeroelastic analysis takes into account spanwise out-of-plane bending and torsion only, for which the corresponding shape functions are derived and validated. The use of shape functions allows representing the wing as an equivalent aerofoil whose generalized coordinates are defined at the wingtip according to the Rayleigh–Ritz method. Theodorsen’s unsteady aerodynamic theory is used to estimate the aerodynamic loads. A representative Padé approximation for the Theodorsen’s transfer function is utilized to model the aerodynamic behaviors in state-space form allowing time-domain simulation and analysis. The effect of the segments’ mechanical, geometric, and inertial properties on the aeroelastic behavior of the wing is assessed. Finally, the viability of span morphing as a flutter suppression device is studied.

Effects of Span Morphing on Flutter Characteristics of Subsonic Wing

“…Flutter behavior of Goland wing at 50% extension is analyzed and validated with study from literature [3]. In this configuration, the wing span extends by 50%, thus the semi-span length becomes 9.144 m. A schematic view of the wing at 50% extension is illustrated in Figure 4.…”

“…Ajaj et al [3] reported the flutter speed of Goland wing at 50% extension is at around 100 m/s. In the current study, the flutter speed is found as 104.1 m/s with the error 3.93%.…”

“…Ajaj et al [3] investigated the aeroelastic behavior of VSMW. In their research, the effects of span morphing on flutter are analyzed in detail.…”

Recent developments in the aeroelasticity of morphing aircraft

“…Variable wingspan combines the benefits of both large and small wingspans into a single aircraft, making span morphing an emerging technology that is attractive for multi-mission UAVs. Studies in the literature have adopted span morphing for enhanced flight performance, roll control, and flutter suppression [40,41]. Variable wingspan technologies are usually associated with large changes in the inertia, elastic and aerodynamic forces.…”

Transonic flutter characteristics of an airfoil with morphing devices

“…Based on a lowfidelity aeroelastic model and cantilever uniform morphing wings, the feasibility of active flutter suppression by using morphing device was studied by Ajaj and Friswell. 11 Investigation was also extended into the dynamic behaviour and stability of an axially morphing wing in supersonic airflow 12 to demonstrate that a proposed morphing law is effective for flutter suppression.…”