A tensioned cable as an adaptive tuned vibration absorber for response suppression in rotorcraft

Du Bois, J.L., Lieven, N. and Adhikari, S. (2012) A tensioned cable as an adaptive tuned vibration absorber for response suppression in rotorcraft. In: 25th International Conference on Noise and Vibration engineering, ISMA2012 in conjunction with the 4th International Conference on Uncertainty in Structural Dynamics, USD 2012, Leuven, Belgium, 17-19 Sept 2012, pp. 237-250.

Abstract

Vibration suppression is a key focus in rotorcraft development, where complex periodic aerodynamic loading results in high levels of forcing transmitted through the rotor hub. Reduction of the resultant fuselage response offers benefits in terms of performance and ride quality. While full size rotorcraft have typically employed fixed rotor speeds, newer configurations are increasingly exploring variable rotor frequencies as a means of expanding the flight envelope of the vehicles. It is in this context that active and adaptive vibration control techniques become not only advantageous but necessary. Active methods employ actuation to superimpose forces on the ambient excitation, and range from hydraulic rams attached to the gearbox to piezoelectric elements embedded in the rotor blades to augment the lift. Adaptive methods offer the advantage of significantly lower power requirements, taking advantage of passive vibration absorption devices with adaptable stiffness and damping properties. The tuned vibration absorber (TVA) is a passive device with a long history of success in the mitigation of vibrations; its use has been seen in rotorcraft, for example, in the highly successful bifilar vibration absorber designs. In general, TVAs perform very well under specific operating conditions but are less useful and may even worsen the response when the excitation frequency is outside the design envelope. This paper examines the use of a vibration absorber based on a taught cable, nominally stretched the length of a helicopter tail boom. The absorber can be tuned by changing the tension of the cable, responding to changes in the main rotor frequency. A novel aspect of this configuration lies in the distributed nature of the mass in the cable. This distributed mass produces a range of harmonic response frequencies, any of which may be used as the operational frequency of the device. An advantage offered by this effect is the ability to cover a wide range of frequencies using a small range of cable tensions. A disadvantage is the additional complexity and weight, and the prospect of adverse influence from the extra harmonics. This paper uses theoretical and experimental results to explore the behaviour of the device, highlighting the benefits and the shortcomings to be addressed.

• Item Type: Conference Proceedings
• Additional Information: Volume 1, 2012, pages 237-250.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Adhikari, Professor Sondipon
• Authors: Du Bois, J.L., Lieven, N., and Adhikari, S.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: International Conference on Noise and Vibration Engineering 2012, ISMA 2012, including USD 2012: International Conference on Uncertainty in Structure Dynamics

Related URLs

• Other