Aeroelastic study of a multi-hinged wing

Abstract

Dynamic aeroelastic response of multi-segmented hinged wings is studied theoretically and experimentally in this thesis. For the theoretical study, a method of modeling the aeroelastic characteristics of multi-hinged wings is proposed. The method employs the Runge-Kutta scheme to solve the governing equations of a flexible multibody dynamic system. The Henon method is used to switch between bilinear stiffness states of the wing in bending. Experimental wind tunnel tests of one- and five-hinged wings were conducted for better insight into the mechanics of the motion. Correlation between the experimental and theoretical results is presented. The theoretical model is found to capture both the linear and nonlinear aeroelastic behavior of a hinged wing. Adding hinges to a wing is found to significantly alter the speed at which an instability will occur. The stiffness of the hinges is found to play a major role in the determination of flutter speeds with a reduction in hinge stiffness nominally leading to an increase in first bending / first torsion instability speeds. However, for low hinge stiffness, hinged wings were also found to have the possibility of a second bending / first torsion instability at speeds far below the first bending instability. The hinged wing is found to enter into chaotic or limit cycle motion at speeds at, near, or above flutter speeds. The bi-linear nature of a hinge is found to cause a disruption in the coalescence of modes. This limits the energy added to the system while it is in an unstable state. The hinges allow the wing to "fold" under low net loads. The theoretical model can be used for aeroelastic design of future hinged wings for remotely deployable vehicles.