Industrially-inspired Gust Loads Analysis of Various Aspect Ratio Wings Featuring Geometric Nonlinearity

This paper considers the effect of geometric nonlinearty on gust load analyses of high aspect ratio commercial aircraft. Three variants of a conceptual aircraft,featuring wing aspect ratios of 10,18 and 26,are sized using an industrially-inspired procedure to obtain realistic structures of existing and future designs. These aircraft are modelled in a nonlinear aeroelastic framework, featuring a geometrically-exact beam formulation coupled with unsteady aerodynamics, and subjected to a gust loads process adapted for nonlinear systems. The gust analysis is also carried out using a linear approach (linearising the equations of motion about an undeformed or trimmed geometry) to understand how nonlinearities influence the loads and dynamic behaviour of aircraft as the aspect ratio increases. Load envelopes show that vertical shear and bending moments are predicted well by the linear analyses, even for the aspect ratio 26 case, providing that the linearisation is performed about the trimmed geometry. In contrast, the in-plane and axial loads are significantly underestimated using linear analyses. Torque behaviour is problem specific,and therefore difficult to generalise. Even on the aspect ratio 10 case,which would traditionally be considered as a linear problem, it can shown that the torque loads are considerably affected by nonlinearity