Flutter analysis of highly flexible wings using higher-order 1D structural theories

This paper presents a computational framework for the aeroelastic analysis of highly flexible high-altitude wings. The structural model is formulated within the Carrera Unified Formulation (CUF), which incorporates lowerand higher-order beam models and uses both Taylor and Lagrange expansion functions for the cross-section kinematics. The Vortex Lattice Method (VLM) and Doublet Lattice Method (DLM) are adopted for aerodynamic loads, and the Infinite Plate Spline (IPS) technique is employed for mesh-to-mesh mapping. A key element of the approach is the piecewise linearization strategy for flutter analysis. Static aeroelastic equilibrium is first computed iteratively under specified flight conditions; the tangent stiffness matrix is then extracted at the equilibrium state, and modal analysis is performed. The p-k method determines the flutter boundary. Numerical investigations of a benchmark High-Altitude Long-Endurance (HALE) wing show that geometric nonlinearity significantly reduces the flutter speed. Furthermore, DLM aerodynamics predicts 10–15% higher flutter speeds than strip theory. The CUF-based predictions show good agreement with reference solutions from the literature, underscoring the proposed framework’s capability to support preliminary aircraft design through fast, efficient aeroelastic analyses based on 1D finite elements.