Supersonic Flutter and Buckling Optimization of Tow-Steered Composite Plates

Abstract

The supersonic aeroelastic stability of tow-steered carbon reinforced composite panels, in each layer of which the fibers follow curvilinear paths, is assessed. A structural model based on the Rayleigh–Ritz method, combined with the aerodynamic piston theory, is derived to represent the aeroelastic behavior of rectangular plates under different boundary conditions. In this model, the classical lamination theory, considering a symmetric stacking sequence and fiber trajectories described by Lagrange polynomials of different orders, is used. In addition, manufacturing constraints, which impose limitations to the feasible fiber trajectories, and the effect of in-plane loads are considered in the model. Using a multicriteria differential evolution algorithm, numerical optimization is performed for a variety of scenarios and aimed at increasing the flutter and linear buckling stability margins of tow-steered plates, considering the geometrical parameters defining the fiber trajectories on the layers as design variables. The results obtained for the different optimization scenarios are compared, having a composite plate with unidirectional fibers as the baseline and aimed at evaluating the benefits achieved by the optimum tow-steered plates. The results enable quantification of the stability improvements by exploring fiber steering, which has been shown to be beneficial, even in situations in which manufacturing constraints are accounted for.