A passive dynamic control approach for aircraft wing structures

Abstract

This research explores an effective method of introducing dynamic vibration absorbers to highly flexible aircraft wings, addressing the challenges of spatial constraints and the effective transmission of control forces. Besides static aeroelastic loads incurred during manoeuvres, dynamic loads and flutter instability constraints pose significant challenges to the design of aerodynamically efficient and light-weight wings. Meeting these dynamic aeroelastic criteria with the tailoring of the structural design alone can incur a substantial weight penalty. Passive dynamic augmentation approaches, whilst scarcely explored in application to wings, offer a potential method of addressing such dynamic issues primarily through effective structural damping elevation. Such approaches, when applied in synergy with other load alleviation technologies, can offer extended weight-saving potentials to further improve efficiency.

The motivation for the approach investigated in this thesis stems from recognising the fundamental need for sufficiently localised relative motions in the structure to effectively integrate damping treatments. In the context of aircraft wings which exhibit global motions, such a structural displacement is not readily accessible to a vibration suppression device that needs to be integrated internally to the structure. This research implements a localised dynamically tuned absorber which couples through the axial displacement of an internally guided tendon which aggregates motion imposed by the motion-induced curvature of the wing. This configuration further permits the integrability of grounded devices, such as damping elements which enables extended damping elevation capabilities.

By exploiting the effective structure-absorber coupling enabled by this approach, this research develops a comprehensive numerical-experimental analysis of the flutter-suppression capability in application to a flexible wing demonstrator. The ability to completely suppress an airspeed-bounded flutter instability with an appropriately tuned absorber is demonstrated. The underlying modal characteristics and the limit cycle oscillations observed with the absorber detuned are characterised. The conceptualised absorber implementation is then numerically studied in application to problem parameters representing the wing structure of a typical regional aircraft. With a case study exploring a two degree of freedom absorber for multi-modal suppression, the damping ratio of a weakly damped aeroelastic mode was elevated by about 5-10% whilst simultaneously improving the damping of the flutter mode to increase the flutter onset speed by about 20%.

Date of Award	9 Dec 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	Branislav Titurus (Supervisor), Ben K S Woods (Supervisor) & Mark H Lowenberg (Supervisor)