A Preliminary sizing tool for minimum weight aircraft wingbox structural design

Mert, Mesut
This thesis presents a preliminary structural sizing tool for the design of aircraft wingbox structures. The primary goal is to obtain the least possible structural weight for a metallic wingbox by using the thin walled multi-cell box beam methods in the literature as part of an iterative process. An automatized tool based on simple and quick approximate methods is created to take advantage in the preliminary stages of design when several possible structural alternatives are being investigated. Airfoil data, material properties, wing geometry and layout (chord, span, taper, spar locations, stringer locations, rib locations, etc.) are the user inputs for the generated tool. Internal loads are then obtained by integrating the external loads along the wing span. Corresponding failure criteria of the structural elements are checked to have a marginal structural sizing for light-weight design. Different internal load distribution methods are used for the subsonic and the supersonic air vehicles. For subsonic wings, internal load redistribution after skin local buckling is also covered. A new method, offering consecutive application of linear static finite element analysis to approximate the post-buckling load redistribution, is introduced within this thesis. The offered method is validated by a comparison with nonlinear finite element analysis.