DESIGN OPTIMIZATION AND ANALYSIS OF AIRCRAFT LANDING GEAR

Abstract

Landing Gear is a vital structural unit of an aircraft which enables to take off and land safely on the
ground. A variety of landing gear arrangements are used depending on the type and size of an aircraft. Even during
a normal landing operation heavy loads are to be absorbed by the landing gear. In turn joints are to be provided
such that such heavy concentrated loads are first received by the airframe and subsequently diffused to the
surrounding areas. Normally heavy concentrated loads are received through a lug joint. Therefore design of a lug
joint against failure under static and fatigue loading conditions assumes importance in the development of an
aircraft structure. This project deals with the design and analysis of a typical lug joint representative of a landing
gear attachment of a small airplane. The design will provide safety against failure of the lug and failure of the pin in
Catia. A typical landing load case will be assumed for which structural analysis will be carried out. During landing,
there will be three different types of loads like Vertical load, Drag load, and Side load. As a first approximation the
landing gear space structure will be idealized as a statically determinate structure and a stress analysis will be
performed using strength of material approach. The stresses developed because of loads on the structural members
of the landing gear will be calculated. A finite element model of the landing gear structure will be developed and
analyzed in Ansys. The FEA stress and deformation results will be compared. These stresses and internal loads can
then be used for the design of various structural members of the landing gear unit. Fatigue life to crack initiation
will be estimated for a critical lug of the landing gear unit by considering the constant amplitude landing cycles