Estimation of Critical Aeroelastic Damping Using Dynamic Eigen Decomposition and Artificial Damping

Aeronautical industry has primarily relied on the p-k method for aeroelastic damping extrapolation. The p-k method can be numerically unstable in regions where modes are close to one another, and repeated iterations of the eigenproblem are required making the approach expensive. In this paper, an entirely new approach for aeroelastic damping estimation is proposed. It uses the Dynamic Eigen Decomposition to find flutter points adjusted by an artificially imposed structural damping. Based on the new aeroelastic equations of motion modified with the artificial structural damping, neutrally stable solutions are found. The amount of the negative structural damping added is interpreted as the true aeroelastic damping at the subcritical point. This analysis is carried out using the Nyquist stability criterion applied to the perturbed system from a nominal stable condition. For demonstration, Goland wing model with six structural modes at Mach=.7 is examined. It is shown that the proposed method can yield aeroelastic damping of critical modes, i.e., lightly damped modes, accurately close to the results of the p-k iterations without causing the mode tracking issue.