Flutter Analysis for Folding-Wing Aircraft Considering Rigid–Flexible Coupling

Abstract

Folding-wing aircraft, a category of morphing aircraft, enhance multimission adaptability through wing configuration changes. However, they face a critical flight safety issue: aeroelastic stability during dynamic morphing processes. This paper investigates aeroservoelastic modeling, flutter analysis, and control strategies for a folding-wing system considering rigid–elastic coupling effects. First, a parametric dynamics model is established in the mean body-axis frame using Lagrange equations, which is linearized to obtain a linear parameter-varying state-space model with the folding angle and Mach number as scheduling variables. Subsequently, systematic analysis of open-loop flutter characteristics across different configurations reveals flutter boundary degradation and mode switching phenomena induced by rigid–elastic coupling. To address the flutter issue during morphing, a linear-quadratic-Gaussian-based flutter suppression control law is designed, incorporating frequency-weighted balanced truncation for controller order reduction and an inertia switching strategy to ensure control smoothness throughout the entire folding range. Numerical simulations demonstrate that the proposed control method effectively expands the flight envelope, significantly improves the system flutter boundary, and demonstrates the effectiveness and engineering applicability of the modeling and control strategies.