A refined aeroelastic beam finite element for the stability analysis of flexible subsonic wings

In this work, a novel finite element approach for the computational aeroelastic analysis of flexible lifting structures in subsonic flow is presented. The numerical simulation of the fluid-structure interaction relies on the physical concept and mathematical formulation of an aeroelastic beam element, that is based on Euler-Bernoulli and De Saint-Venant theories for the structure dynamics and modified strip theory for the unsteady airload. An implementation of the unsteady vortex lattice method is used to correct standard strip theory in the time domain, considering the actual wing geometry and taking the aerodynamic effects of its sweep, aspect ratio and taper ratio into account. The effects of shed and trailed vorticity on the sectional load development and distribution are also accounted for, within a hybrid semi-analytical reduced-order aerodynamic model. Building on previous works, the present computational framework for aeroelastic modelling and simulations of flexible lifting structures is investigated and validated through a parametric stability assessment of swept tapered wings. The aeroelastic beam element proves to be an intuitive, reliable and efficient reduced-order tool, well suited for the preliminary multidisciplinary design and optimisation of flexible aircraft.