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Title: Aircraft NLG shimmy : methods, tools and analysis
Author: Davidson, Gordon Westly
ISNI:       0000 0004 2732 5446
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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ELGEAR was a UK government/industry partnership created in 2006 to research electrical technology in aircraft landing gear systems. The project designed, built and ground tested electrical technology for a Landing Gear Extension/Retraction system (LGERS) and Nose Wheel Steering systems (NWS) for a 120 passenger aircraft. One thread of this research, and the topic of the present thesis, was to develop analysis methods and tools to investigate the effects of shimmy. Shimmy is the self excited vibration of a castored wheel assembly. It may be experienced on assemblies such as wheel chairs, shopping trolleys, motor cycles, and it is particularly prevalent on aircraft landing gears. Developed within this report is a generic set of system shimmy requirements to guide future engineers. Several models are developed from first principles, allowing a potential design to be quickly evaluated and damper sizes determined. A detailed Multi-Body Systems model has been created using the software modelling package ADAMS. The model includes a detailed representation of mass and inertia properties, stiffness’s, friction and tyre properties. The report includes a detailed method to determine the tyre parameters compatible with the ADAMS PAC2002 formulation (magic tyre formula). The dynamic model is simulated to investigate the landing gear’s behaviour to each requirement and is a significant enhancement to the models developed using first principles. To explore the influence of higher frequency tyre dynamics, a model incorporating a simplified SWIFT tyre model is generated from first principles. The report concludes with a validation of the methods and tools. Test results are used to validate several aspects of the tyre model, and a comparison between hand derived models and the detailed model provides a thorough check of modelling practices.
Supervisor: Evangelou, Simos ; Neal, Rob ; Evans, Roy Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available