Efficient Nonlinear Aeroservoelastic Modeling for Morphing Wing with Bilinear Stiffness

Abstract

In this paper, a novel nonlinear aeroservoelastic modeling methodology for a morphing wing with bilinear stiffnesses in hinge joints is proposed to investigate the nonlinear aeroservoelastic behaviors during the morphing process efficiently. The notable advantage is that the bilinear nonlinearity in hinge joints and the variation of morphing configuration is modeled theoretically using a parameterized fictitious mode approach. The nonlinear, parameter-varying aeroservoelastic system is represented by piecewise-linear modal-based aeroservoelastic equations according to the different combinations of nonlinear parameters in hinge joints. The proposed nonlinear aeroservoelastic modeling methodology can efficiently investigate aeroservoelastic frequency responses, nonlinear aeroservoelastic vibration, and closed-loop stability because the nonlinear aeroservoelastic model is built via the parameterized fictitious modal coordinates, which can represent the bilinear structural stiffness and variation of morphing parameter simultaneously. To demonstrate the modeling accuracy and efficiency of the present method, a folding wing with two bilinear stiffnesses due to backlash in inboard and outboard hinge joints is selected as a test case. The numerical results show that the open-loop and closed-loop nonlinear behaviors of the morphing wing at different folding configurations can be efficiently investigated. Also, the chaotic phenomenon of the morphing wing subject to control surface excitation was firstly found.