Interaction of torsion and lateral bending in aircraft nose landing gear shimmy

Abstract

In this paper we consider the onset of shimmy oscillations of an aircraft nose landing gear. To this end we develop and study a mathematical model with torsional and lateral bending modes that are coupled through a wheel-mounted elastic tyre. The geometric effects of a positive rake angle are fully incorporated into the resulting five-dimensional ordinary differential equation model. A bifurcation analysis in terms of the forward velocity and the vertical force on the gear reveals routes to different types of shimmy oscillations. In particular, we find regions of stable torsional and stable lateral shimmy oscillations, as well as transient quasiperiodic shimmy where both modes are excited.

Effects of Freeplay on Dynamic Stability of an Aircraft Main Landing Gear

“…2 Our focus here is on main landing gear (MLG) shimmy. 3 In a previous study 4 we used a nonlinear model with three DoFs to express the dynamics of a MLG of dual-wheel configuration, using numerical continuation methods to study the onset of shimmy oscillations.…”

Numerical continuation analysis of a three-dimensional aircraft main landing gear mechanism

“…Several recent applications of dynamical systems methods have demonstrated the advantages that they can offer in an aerospace context; this includes the analysis of aircraft ground dynamics [7,8], the study of nose landing gear shimmy [9] and NLG mechanism modelling [2]. To be able to use these dynamical systems methods for analysing landing gear mechanisms, the mechanism configuration and internal force distribution is formulated as a system of coupled equations, which are inherently nonlinear due to various geometric constraints.…”

Upset Dynamics of an Airliner Model: A Nonlinear Bifurcation Analysis

“…A number of continuation software packages are available; this study uses AUTO [40], which is ground dynamics [41], landing gear shimmy [42], landing gear mechanisms [43] and, in addition, to flight dynamics [25] and control [44].…”