Thickening of optimally selected locations on panels subjected to unyawed flow for substantial delay of the panel flutter

Abstract

In the current research, optimal locations on aircraft panels are thickened to delay the flutter occurrence. A standard square isotropic Aluminum panel of 12 × 12 in. is considered. In formulating the model, the Kirchhoff-Love hypothesis and the Von-Karman nonlinear strain-displacement relations are applied. The quasi-steady first-order piston aerodynamic theory is used to calculate the applied load and the aerodynamic heating effects are not considered. In deriving the nonlinear equations of motion, the four-node Bogner Fox-Schmit (BFS) rectangular plate element is considered and the modal transformation is applied to decrease the calculation time. An ad hoc optimization method is implemented to achieve the objectives of the current research. The thickness, location, and the number of elements represent the parameters of the objective function. Many combinations between the number of elements, the arrangement of these elements, and the thickening values substantially delayed the flutter occurrence. In some cases, the corresponding critical aerodynamic values could be more than the double of the critical aerodynamic value of the pristine panel. Finally, to some extent, the current proposed technique can replace the dominant multifaceted active flutter damping techniques, which are more complex and more expensive.