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A bifurcation study to guide the design of a landing gear with a combined uplock/downlock mechanism

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posted on 18.11.2014, 13:38 by James KnowlesJames Knowles, Mark H. Lowenberg, Simon A. Neild, Bernd Krauskopf
This paper discusses the insights that a bifurcation analysis can provide when designing mechanisms. A model, in the form of a set of coupled steady-state equations, can be derived to describe the mechanism. Solutions to this model can be traced through the mechanism's state versus parameter space via numerical continuation, under the simultaneous variation of one or more parameters. With this approach, crucial features in the response surface, such as bifurcation points, can be identified. By numerically continuing these points in the appropriate parameter space, the resulting bifurcation diagram can be used to guide parameter selection and optimization. In this paper, we demonstrate the potential of this technique by considering an aircraft nose landing gear, with a novel locking strategy that uses a combined uplock/downlock mechanism. The landing gear is locked when in the retracted or deployed states. Transitions between these locked states and the unlocked state (where the landing gear is a mechanism) are shown to depend upon the positions of two fold point bifurcations. By performing a two-parameter continuation, the critical points are traced to identify operational boundaries. Following the variation of the fold points through parameter space, a minimum spring stiffness is identified that enables the landing gear to be locked in the retracted state. The bifurcation analysis also shows that the unlocking of a retracted landing gear should use an unlock force measure, rather than a position indicator, to de-couple the effects of the retraction and locking actuators. Overall, the study demonstrates that bifurcation analysis can enhance the understanding of the influence of design choices over a wide operating range where nonlinearity is significant.

Funding

This work was supported by Airbus in the UK, and by an EPSRC mathematics CASE award. The research of S.A.N. was supported by an EPSRC fellowship [grant number EP/K005375/1].

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences

Volume

470

Issue

2172

Citation

KNOWLES, J.A.C. ... et al, 2014. A bifurcation study to guide the design of a landing gear with a combined uplock/downlock mechanism. Proceedings of the Royal Society of London. Series A. Mathematical, Physical and Engineering Sciences, 470 (2172), 20140332.

Publisher

The Royal Society / © The Authors

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

02/10/2014

Publication date

2014-12-08

Notes

This is an Open Access Article. It is published by The Royal Society under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

ISSN

1364-5021

eISSN

1471-2946

Language

en

Article number

20140332