Analysis of Low-Aspect-Ratio Aircraft Structures

Abstract

Summary Two methods are presented for the analysis of complex lowaspect-ratio aircraft structures. Both methods provide for arbitrary external loading, are general with respect to the orien­ tation of structural members, and permit arbitrary boundary conditions. For purposes of analysis a structure is idealized as a network of flexural members with interconnected torsion boxes. In the first method, sets of linear equations are obtained by expressing boundary conditions, member deflection equations, equilibrium requirements, and slope-compatibility relationships in terms of deflections and internal forces. The solution for deflections and internal forces is then formed as the product of an inverse structural matrix and a column matrix of load functions. In the second method, the conditions at a given boundary are assembled as a column matrix and are transferred in a step-bystep fashion over the entire structure to an opposite boundary. The transfer is accomplished by successive multiplications of square matrices composed independently for the different trans­ fer ranges. The final operation is the inversion of a relatively small matrix and provides the solution for the unknown boundary conditions.