Parameter-identification-based time-varying aeroelastic modeling framework and wind-tunnel tests for a folding-wing model

This paper presents a time-varying aeroelastic modeling framework for folding wings undergoing large, continuous morphing, with an emphasis on parameter identification. In the framework, the time-varying stiffness of the actuation system is identified from time-domain responses by extracting instantaneous frequencies and minimizing the discrepancy between identified and simulated frequencies at each time step. The identified stiffness is then incorporated into a time-varying structural dynamics model formulated using the floating frame of reference. The structural model is coupled with an unsteady vortex lattice method to simulate the transient aeroelastic responses under arbitrary flow conditions. A simulation example verifies the accuracy of the stiffness identification strategy. The wind-tunnel experiments validate and characterize the nonstationary vibration characteristics during the morphing process. The comparison between simulations and experiments demonstrates that the proposed framework accurately captures the time-varying aeroelastic behavior of the folding wing. The results reveal that the folding and unfolding processes exhibit opposite aeroelastic responses. In addition, the morphing rate plays a critical role in determining dynamic stability. The primary contribution of this work lies in integrating frequency-based system identification with a parametric, time-varying aeroelastic modeling framework, providing a practical, experimentally grounded approach to analyzing and predicting the stability of morphing wing systems.