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On the performance of a nonlinear vibration isolator consisting of axially loaded curved beams

Abolfathi, A; Waters, TP; Brennan, MJ; (2013) On the performance of a nonlinear vibration isolator consisting of axially loaded curved beams. In: Proceedings of the 11th International Conference on Recent Advances in Structural Dynamics. Institute of Sound and Vibration Research (ISVR): Pisa, Italy. Green open access

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Abstract

A desirable characteristic for nonlinear vibration isolators is a high static stiffness and a low dynamic stiffness. A curved beam is a possible candidate for this role provided that the amplitude of vibration about the static equilibrium position is sufficiently small. However, for large amplitude oscillations, the nonlinear dynamics may have a detrimental effect. This paper considers the force transmissibility of a single degree-of-freedom system where the stiffness element is a curved, axially loaded beam. The transmitted force is calculated by numerical time domain integration of the equations of motion. The exact force-deflection relation for the beam is used for the spring. By comparison, a frequency domain solution is sought using the Harmonic Balance (HB) method in which the system is modelled as a Duffing oscillator. It is shown that the HB and time domain solutions are in close agreement for small amplitudes of excitation and both predict advantageous performance of the nonlinear isolator compared with its equivalent linear counterpart. However, significant discrepancies occur between the two solutions for large excitation since the beam can no longer be approximated by a linear and a cubic stiffness. It is also strongly asymmetric – soft in compression but stiff in extreme extension– which gives rise to an impulse in the transmitted force in each fundamental period. This numerical problem is alleviated by inserting a linear spring in series with the beam isolator with a modest compromise in isolation performance at the excitation frequency.

Type: Proceedings paper
Title: On the performance of a nonlinear vibration isolator consisting of axially loaded curved beams
Event: 11th International Conference on Recent Advances in Structural Dynamics (RASD 2013)
Location: Pisa, Italy
Dates: 01 July 2013 - 03 July 2013
Open access status: An open access version is available from UCL Discovery
Publisher version: https://www.southampton.ac.uk/engineering/news/eve...
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: vibration isolators, nonlinear vibrations, Duffing oscillator, numerical solution
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1557954
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