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One of the problems faced by the aircraft community is the landing gear dynamics, especially the shimmy. Non-linear behaviour of landing gear makes the evaluation of the shimmy phenomenon more complex and its prediction more difficult. Notably the non-linearities in landing gear torsional free play tend to destabilize the landing gear, whereas the frictional non-linearity dissipates energy and thus increases the landing gear stability. This article presents the study of the shimmy instability of a typical nose landing gear model developed based on the Li formulations with torsional free play. Finally, the study has been performed to postpone the dynamic instability by introducing magneto rheological fluid-based damper.

Shimmy is an oscillation in the nose landing gear (NLG) of an aircraft that may occur during taxiing, take-off or landing. Increasing emphasis on reducing the weight of landing gear systems in modern aircraft has, in many cases, induced shimmy problems and active vibration control has gradually been used to suppress vibration. The objective of the current investigation is to introduce an active torsional magneto-rheological (MR) fluid-based damper for shimmy vibration control of a typical NLG. In the present study, the shimmy model is developed based on the formulation of G. X. Li, to study the self-induced dynamic instability at the critical forward taxi velocity. The effect of various parameters on the shimmy behaviour is also studied. The study has been performed to postpone the dynamic instability by introducing MR fluid-based damper as a semi-active device and also a closed-loop feedback control scheme is employed to control the landing gear instability of an aircraft.

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