Application of Multiple Methods for Aeroelastic Uncertainty Analysis

Flutter is a potentially explosive phenomenon that is the result of the simultaneous interaction of aerodynamic, structural, and inertial forces. The explosive nature of the flutter phenomenon mandates that flutter flight testing be cautious and conservative. It is therefore clear that further investigation of uncertainty analysis methods with respect to the flutter problem is desired and warranted. The analytical prediction of flutter in the transonic regime requires high fidelity simulation models that are computationally expensive. Due to the computational demands, traditional uncertainty analysis is not often applied to flutter prediction, resulting in reduced confidence in the results. The work described herein is aimed at exploring methods to reduce the existing computational time limitations of traditional uncertainty analysis. Specifically, the coupling of Design of Experiments (DOE) and Response Surface Methods (RSM), and the application of robust stability techniques, namely µ-analysis, are applied to an example aeroelastic model. From a high fidelity nonlinear aeroelastic simulation, a linear Reduced Order Model (ROM) is produced that still captures the essential dynamic characteristics. Using ROMs, the DOE/RSM and µ-analysis approaches are compared to traditional Monte Carlo based stochastic simulation. All of these approaches to uncertainty analysis have advantages and drawbacks. The multiple methods and their robustness are compared and evaluated with a validated aeroelastic model of the AGARD 445.6 wing.