Nonlinear Low-Fidelity Numerical Model of the Flared Folding Wingtip

Previous numerical and experimental studies have shown the load alleviation capabilities of the flared folding wingtip. However, they have also shown the complex dynamics of the system and the limitations in the results obtained by modeling such an aeroelastic system using linear models, which cannot capture the effects of the large wingtip deflections. Therefore, the current study presents a nonlinear time domain flexible multibody model comprising a linear beam representing the main wing, and a rigid body representing the wingtip and its nonlinear effects. In addition, the time domain model allows the simulation of the hinge release based on the load threshold, which was also studied experimentally. The structural model is coupled to quasi-steady aerodynamics strip theory to model the aerodynamic loads. The aerodynamic model is refined using the experimental steady-state results from the previous work and then compared to the experimental gust response from the same study. The model presents good agreement with the experimental results in the case of low and moderate-frequency gusts. However, the agreement is worse for high-frequency gusts as expected due to the assumption of quasi-steady aerodynamics. Furthermore, the model captures the same trends observed in the experiment for the hinge release load threshold. Finally, the time-marching model is also used to assess the nonlinear stability boundaries and the occurrence of limit cycle oscillations.Aerospace Structures & Computational Mechanic