Robust Flutter Analysis for Certification

A number of critical parameters which determine the stability of an aeroelastic system are usually obly known to within a certain bound, but not exactly. As the number of these parameters increases with the complexity of the system, performing flutter solutions for all possible parameter values becomes infeasible.


Dan Borglund, PhD

By exploiting methods developed for mu-synthesis in the field of Robust Control System Design, the uncertain nonlinear flutter eigenvalue system is expressed as a structured singular value problem. Computation of bounds for the singular value then yields the stability of the worst case of all possible variation of the uncertain parameters.

As demonstrated in a previous NFFP-4 project, this technique can be used to quantify aerodynamic uncertainties in a given model by comparison with flight flutter test results. This, in turn, then allows to improve predictions of the stability boundary. The current project aims primarily at improving the applicability of the methods developed, for instance by including the effect of mass and inertia uncertainties.


This project is conducted in collaboration with Saab Aerosystems under the framework of the fifth Swedish Aeronautics Research Program (NFFP-5), financed by Vinnova, The Swedish Governmental Agency for Innovation Systems.

Page responsible:David Eller
Belongs to: Aeronautical and Vehicle Engineering
Last changed: Oct 07, 2009