In recent years a significant effort has been devoted to the study of more energy efficient aircraft that will meet the environmental goals set out in initiatives such as Vision 2020 and Flight Path 2050. Some of these studies have considered the implementation of new aircraft concepts that can provide enhanced performance in terms of overall aircraft efficiency and noise. One such concept is the truss-braced wing aircraft, which has been shown to provide an overall benefit to aircraft mass and fuel-burn by virtue of its high-aspect ratio wing and efficient structural design. However aeroelastic phenomena such as flutter and gust loads place a limit on the practical efficiency savings that can be achieved by adopting a braced-wing design, therefore any mechanism by which these negative aeroelastic effects can be mitigated will be a key enabler for the success of this concept. This thesis investigates the possibility of achieving gust loads alleviation and flutter suppression in a truss-braced wing via passive vibration control. A full-scale aircraft model based on the NASA/Boeing SUGAR concept aircraft is used to run a series of studies where a vibration suppression device is included in the truss structure and the device properties are optimised in order to suppress flutter and minimise gust loads. Different device layouts are considered including devices that can be frequency-tuned to target specific modes of the structure. The results for the SUGAR-inspired model demonstrate that improvements in flutter speed between 1 - 6% and reductions in gust loads of approximately 4% are achievable with an almost negligible mass penalty from the device. It is also noted that further benefits could be realised if the design of the device was included as part of a wider structural optimisation. Finally, the methods used in this thesis can be used to model a generic vibration absorber attached to any generic finite element model, fundamentally enhancing the scope for vibration suppression devices to be considered in the design and optimisation of large and complex systems.
- vibration suppression
- truss-braced wing