Development and Verification of an Aircraft Flutter Analysis with Uncertainty

Abstract

For the modern aircraft, uncertainty may be an important issue to its aeroelastic stability. Therefore, many researches have been performed regarding this topic. In this paper, we assume that an uncertainty exist in aircraft structural and aerodynamic characteristics. At first, we predict flutter speed and frequencies by using parametric uncertainties. We formulate the generalized mass and stiffness matrices for a three-dimensional wing. We also derive its generalized aerodynamic forces. These matrices are based on the structural mode shapes. We convert them into the modal mass and stiffness matrices and predict an influence by the weight value of uncertainties in the coupled mode. In this paper, we also perform a robust analysis by mu-method which considers aerodynamic uncertainties. We use the doublet lattice method (DLM) to obtain a detailed unsteady aerodynamic force. We verify aerodynamic uncertainty magnitude by DLM in accordance with Mach number. Then, we obtain a state-space form of the aerodynamic force by rational function approximation to find the variation range of the poles and zeros. Finally, we analyze the worst case by the mumethod which considers an aerodynamic uncertainty.