Parametric study of a novel nose landing gear shimmy damper concept

Abstract

Shimmy dampers are passive solutions for undesired shimmy vibration in aircraft landing gears. Although they mitigate shimmy to variable degrees, they can introduce weight, cost, and reliability penalties especially when added to existing landing gear systems. More effective and compact shimmy dampers with reduced maintenance effort and enhanced stability performance can then greatly contribute to light-weighting, as well as lowering the aviation risk and maintenance costs. Moreover, a robust performance analysis and characterization framework based on high-fidelity computational models is absent from the literature while it is essential to quantify the capabilities of a given damper. In this work, analysis of a novel shimmy damper concept is presented along with an effective methodology for evaluating the performance of shimmy dampers based on nonlinear shimmy amplitude maps and stability boundary plots. The new damper concept is suitable for installation on existing and new landing gears and features a multifunctional torque link member including an assembly of beam and damping units to suppress the undesired vibrations. The influence of torque link damper parameters is then thoroughly explored using the nonlinear Multibody Dynamics model of the nose landing gear employed for both generating the shimmy maps and time histories of the vibrations. The novel concept is shown to be capable of effectively mitigating the rotational shimmy given that the parameters are chosen appropriately based on the systematic approach laid out. The insights from the analysis are then distilled in the form of recommendation for designing next generation shimmy dampers. Moreover, the novel framework introduced for characterizing shimmy dampers offers great benefit to the shimmy suppression research and development practice.