Macro-mechanical Analysis on the Variation of Fibre Orientation in a Composite UAV Landing Gear

Abstract

Composite materials are increasingly being relied upon for their light weight and high strength to weight ratios and form the backbone of the aerospace industry, which follows a Systems Engineering approach. This paper is an attempt to manifest such an approach at a relatively smaller scale for a composite UAV landing gear. The landing gear acts as a support structure for the fuselage during take-offs and landings and hence needs to be carefully designed, analyzed and manufactured. The strength and weight of a landing gear has to be optimized so as to adhere to the overall aerodynamics and structural integrity of the aerial system. This study is initiated with the design concept of the landing gear and the state of load being acted upon followed by appropriate composite material selection. An approximate number of layers are decided for the composite vacuum layup of the landing gear through iterative experimentation. The fibre orientation of the composite layers is instrumental in gauging the macro-mechanical performance of the composite, thus being the focal point of this study. To execute this, the extensional, coupling and bending stiffness matrices are computed in a mathematical model in MATLAB for different fibre orientations in response to the elastic constants of the fibre and matrix. The global and local strains and curvatures are calculated for a load case and the final combination is down-selected. Corresponding to the down-selected combination, the landing gear is finally fabricated, using Vacuum bag moulding.