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Title: A bifurcation study to guide the design of a landing gear with a combined uplock/downlock mechanism
Authors: Knowles, James A.C.
Lowenberg, Mark H.
Neild, Simon A.
Krauskopf, Bernd
Keywords: Landing gear mechanism
Numerical continuation
Bifurcation analysis
Issue Date: 2014
Publisher: The Royal Society / © The Authors
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.
Abstract: 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.
Description: 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/
Sponsor: 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].
Version: Published
DOI: 10.1098/rspa.2014.0332
URI: https://dspace.lboro.ac.uk/2134/16255
Publisher Link: http://dx.doi.org/10.1098/rspa.2014.0332
ISSN: 1364-5021
Appears in Collections:Published Articles (Aeronautical and Automotive Engineering)

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