Supersonic Aerodynamic Instability Characteristics of Bidirectional Porous Functionally Graded Panel

Abstract

Abstract The objective to alleviate the detrimental effects of supersonic flutter of aerospace structures necessitates the development of advanced composite materials. Porous functionally graded materials are viable alternatives to replace the metal/alloys used for critical components. The present work investigates the supersonic flutter characteristics of hinged-hinged panel for the porosity grading across the thickness and/or along the streamwise direction. Also, the possibility to alleviate the detrimental effects is investigated through the study of influence of streamwise and spanwise curvatures. A geometrically nonlinear finite element model of panel is derived using first-order shear deformation theory while the aerodynamic pressure on panel is accounted using the first-order piston theory. The results revealed that symmetric distribution of porosity with minimum porosity at the midspan and maximum porosity at core displays the better performance. Porosity and streamwise curvature reduces critical aerodynamic pressure and enhances flutter amplitude. For higher streamwise curvatures/porosity, panel undergoes snap-through buckling resulting in complex vibrations. Whereas the spanwise curvature substantially enhance the critical dynamic pressure thereby eliminates complex oscillations and snap-through. But moderately increases the flutter amplitude and frequency beyond its critical aerodynamic pressure. At higher spanwise curvatures, the effectiveness of bidirectional grading decreases making its through-thickness grading as dominant.