Investigation on the effect of coulomb friction on nose landing gear shimmy

Abstract

Landing gear shimmy remains a challenge in aircraft design despite abundant advances in aircraft engineering in the past few decades. Accurate shimmy prediction is closely tied to availability of dynamic models with all relevant types of motions and key nonlinear elements, a matter which has been accomplished in the present study through including rotational, lateral, longitudinal, and axial degrees of freedom and tire, shock absorber, and Coulomb friction nonlinearities. Using multi-body dynamic simulations, stability of the nose landing gear is studied as a function of key system parameters. Influences of nonlinearities are investigated in isolation, with a more in-depth look at the Coulomb friction effect, which is modeled as a function of the shock absorber stroke rate and rotational shimmy speed. It is found that Coulomb friction is a key factor in determining the onset and type of shimmy. The effect of friction parameters is then studied using nonlinear sensitivity analyses, and witnessed trends are utilized to draw design recommendations.

Data-Driven Modeling and Regulation of Aircraft Brakes Degradation via Antiskid Controllers

“…The landing gear may be represented in its entirety, or its parts may be considered separately, depending on the aircraft topology. Specific models have been devised to study certain phenomena in particular operating conditions, such as gear-walk [36], shimmy [37], or response to component failure [38]. For the application at hand, the chosen modelling framework needs to be instrumental for antiskid control system design, be able to replicate the dynamics of the experimental test rig described in Section II, and be as simple as possible to clearly link the braking actuator degradation to the anti-skid design parameters.…”

Investigation on the Effect of Anti-Braking System on Nose Landing Gear Shimmy

“…Landing gear oscillation can impact its own structure and sometimes even cause serious safety accidents. The nose landing gear is more likely to oscillate during highspeed taxiing on the runway than the main landing gear [1]. Therefore, the study on the shimmy of the nose landing gear and the analysis of its influencing factors are very important to improve the safety of aircraft.…”

“…With the further research on shimmy analysis and modeling, the focus of current research has turned to the analysis of influencing factors of shimmy. Rahmani et al [1,7,8] studied the effects of coulomb friction and clearance connecting rods on the shimmy of the nose landing gear. Thota et al [9] studied the effect of changes in tire inflation pressure on the shimmy of the nose landing gear.…”

Bifurcation analysis of vehicle shimmy system exposed to road roughness excitation

“…In addition, Feng et al (2015) found that the squared torsional damping has a significant impact on shimmy when Bautin bifurcation occurs in the dynamic system. Rahmani and Behdinan (2019) studied the influence of the Coulomb friction on the stability of the landing gear by using the multi-body dynamic theory.…”