Analytic Sensitivities in Composite Wing-Shape Ynthesis Part Two: Panel Flutter Constraints

Abstract

The equivalent plate modeling formulation of composite wings, described in Part One, is extended in this paper to include the explicit analytic expressions for terms of the mass and aerodynamic matrices. Analytic sensitivities of the mass and aerodynamic matrices with respect to panel shape, thickness and fiber orientations are derived. Before proceeding in the study of analytic sensitivities using the derived expressions, the accuracy of its panel flutter analysis was numerically tested for simply supported panels of trapezoidal and skewed shape, of isotropic and composite materials and variable fiber orientations. The nondimensional critical dynamic pressure and critical frequency of flutter are compared with the results of finite element flutter analysis of composite skew panels by Chowdary, T.V.R. and al given in "Computers and Structures", (1996). The correlation of the results is good for moderate in-plane loading. Accuracy of the approximations is studied for the integration with nonlinear programming/approximation concept aeroelastic design synthesis methodology.