Resolution of indeterminate landing gear structure design

Bradley James Greenland, Ryerson University

Date of Award

2007

Degree Type

Thesis Project

Degree Name

Master of Engineering (MEng)

Department

Mechanical Engineering

First Advisor

Paul Walsh

Abstract

Aircraft landing gear structural designs involves a balance of weight, cost and robustness while not compromising on safety. On some large commercial aircraft, the introduction of a second main supporting brace has led to an indeterminate structure in that there is redundancy in the load paths. This introduces two major challenges for structural design. The first challenge involves the introduction of a multiple load path. Understanding load path in the landing gear is critical in order to optimize the structure for weight. This report focuses on analysis techniques geared to resolving this indeterminate load path in order to

mitigate this risk and optimize the design. The second major challenge is introduced by a compressive load in one of the braces during an in flight airload condition which impedes the ability for the landing gear to freefall, which is a requirement in aircraft design. Solving this problem involves introducing a pretension in the brace by force shortening the geometry. An indeterminate design introduces increased complexity and requires more simulation and analysis than that of a determinant design in order to accomplish the optimization demanded by the aerospace industry.