The Dynamic Characteristics of a non-linear main landing gear system of an aircraft during landing

Arjun Srivathsa,M V Bharath Narayana,S S Adarsha,Chandrashekara C V,K S Sridhar

doi:10.21595/vp.2020.21393

Abstract

The landing gear plays a very important role during landing by absorbing the high impact energy of the aircraft. The main landing gear absorbs the bulk of the load to reduce the load experienced by both the aircraft fuselage and the nose landing gear. In this paper, a mathematical approach is used to extract the dynamic characteristics of the system. A two-degree of freedom mathematical model of the main landing gear is developed. This model is used to derive the dynamic equations of the landing gear system and to study the behaviour of main landing gear during main gear and nose gear touchdown conditions. The non-linear stiffness and damping co-efficient in an Oleo-Pneumatic shock absorber are integrated into the system to achieve a more accurate response of the system. The response of this system is established by adopting a complex modal analysis approach to account for the non-classical damping exhibited by the system. The obtained spring force, damping force and responses are reported. This work provides an alternative approach using complex modal analysis to obtain results for complex systems exhibiting non-linear characteristics.

Highlights

The landing gear ensures the aircraft lands safely, slows down and has a comfortable trip during taxi
Carried out a discussion on the static and dynamic loading on the landing gear system and concluded that the main landing gear experiences the maximum load when compared to the nose landing gear
Daniels [2] experimented and modelled the main landing gear of Navy A6 Intruder aircraft, with the non-linear characteristics of the oleo-pneumatic shock absorber integrated into the model

Summary

Introduction

The landing gear ensures the aircraft lands safely, slows down and has a comfortable trip during taxi. Daniels [2] experimented and modelled the main landing gear of Navy A6 Intruder aircraft, with the non-linear characteristics of the oleo-pneumatic shock absorber integrated into the model. Gehee et al, [4] developed a mathematical model for an active controlled landing gear and demonstrated compute the loads during a vertical drop test. THE DYNAMIC CHARACTERISTICS OF A NON-LINEAR MAIN LANDING GEAR SYSTEM OF AN AIRCRAFT DURING LANDING. The shock absorber in an aircraft landing gear exhibits non-linear stiffness and damping parameters. The novelty of the present work is to demonstrate the dynamic characteristic of the landing gear, incorporating the non-linear stiffness and damping parameters in the pneumatic shock absorber during touchdown duration using complex modal analysis. Computing code is created in MatLab and is used to extract the natural frequencies, Response, Spring Force and Damping Force of the system during landing

Oleo pneumatic shock absorber

Mathematical model

Results and discussion

Conclusions