On the importance of aerodynamic and structural geometrical nonlinearities in aeroelastic behavior of high-aspect-ratio wings

Theoretical development of a nonlinear aeroelastic analysis for high-aspect-ratio wings is presented. The analysis couples a geometrically exact beam theory with a nonplanar aerodynamic theory. The aim of the present effort is to investigate the effects of geometrical nonlinearities on the aeroelastic behavior of high-aspect-ratio wings. The focus of the present work is on characterizing the physical origins of nonlinearities and assessing their relative importance. Results presented show that the structural geometrical nonlinearities have a significant effect on the structural dynamics and on the dynamic aeroelastic characteristics of a high-aspect-ratio wing. The geometrically exact calculation of the angle of attack and aerodynamically consistent application of the airloads is also important for accurate aeroelastic characterization. On the other hand, the geometrical aerodynamic nonlinearity emerging from the nonplanar wake effects is quite negligible. Nonplanar effects were negligible for both the steady and unsteady airload calculations with the assumption of a fixed wake model. (C) 2004 Elsevier Ltd. All rights reserved.