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Title: Low maintenance bearings for aircraft landing gear
Author: Krier, Peter John
ISNI:       0000 0004 6062 5272
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2016
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Pin joints are utilised in many engineering structures, where movement is required between two components. Typically the joint consists of a shaft rotating through a limited range of motion between the two components, within a bush or set of bushes. Grease lubrication is often incorporated to minimise and ideally prevent direct metal to metal contact. However very seldom is separation achieved, and therefore wear and friction occur. In an aircraft landing gear application, pin joints are widely utilised in the extension retraction mechanism. The replacement of these lubricated metallic bushes with a lightweight polymer alternative could not only lead to reduced maintenance and expensive overhaul of components, but also brings significant weight savings and hence increases in aircraft efficiency from a reduction in fuel burn. A bespoke radial load test rig has been designed and manufactured to simulate the loading conditions imposed upon a pin joint, located in the bracing strut of an aircraft landing gear extension retraction mechanism, as the aircraft manoeuvres on the ground. Four selflubricating polymer composite materials were tested for three aircraft lives and an assessment of the wear and deformation occurring as a result. The co-efficient of friction was evaluated for the four self-lubricating materials and also the current technology in both the lubricated and unlubricated states. The re-lubrication interval was also investigated. The effect of the articulation angle on the co-efficient of friction was investigated for the lubricated and self-lubricating materials. A load displacement model was developed to predict the displacement and contact angle of polymer composite materials under an applied radial load and was experimentally validated. The model uses only geometrical and material parameters, and was shown to be more accurate at higher loads than the current models used.
Supervisor: Dwyer-Joyce, Rob ; Marshall, Matthew Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available