Development of stick models equivalent to a wing-box GFEM to be used in the preliminary design phase

The most important objective of the current thesis research, carried out at the Structures Numerical Analysis Department of Airbus UK, is the development of three algorithms as well as computer programs for computing the equivalent beam stiness distribution of a complex aircraft wing and for generating the corresponding simplified beam finite element model, the stick model. The stick model is very suitable in the iterative process of wing optimization: its basic function is to present accurate prediction of the real structure deformation when it is subjected to similar load conditions and, being a very simple model, it can be recalled thousands of times with very low computational costs and time consuming. After a brief review of the most common methodologies used in the industry for generating the stick model, the algorithm of two of those methods and that of a new one proposed as well as their implementation in an automated program are detailed. It is provided an overview of the Thin Walled Beam Theory and of the Global Finite Elements Models of wing structures; the common modelling practices and the modelling elements of MSC Nastran mostly used in a wing GFEM are described. Furthermore, the thesis represents a user manual for large scale application of the computer programs implemented: the steps required for the transition from a generic wing GFEM to the equivalent stick model, basing on the discussed methodologies, are explained in details. Finally, some representative examples of application are provided, as the stick models of two different wing-box 3-D FEMs are generated using the automated procedures implemented and their performance in similar load conditions are compared with those of the GFEMs in terms of deformations