Buckling effects on the fluid-structure interaction of a viscoelastic, composite panel in a subsonic flow

The use of composite materials in the aerospace field requires some modifications of design and analysis tools to predict particular phenomena that may be detrimental to the performance of a flight vehicle. The study of the interaction of a flexible structure with a surrounding fluid flow is known as aeroelasticity, and two phenomena of interest within aeroelasticity are panel flutter and instability. Panel flutter is the simple harmonic motion of the panel along the panel's perpendicular direction, while instability is the increasing displacement of the panel in the perpendicular direction. Viscoelasticity provides an improved model for composite materials; therefore it is desirable to study a viscoelastic panel in a wind tunnel to determine its flutter performance. Prior to such an experimental study, the effects of buckling on the panel's fluid-structure interaction should be investigated. Buckling during a wind tunnel test for elastic panels has been reported. The simulations indicate that the boundary conditions have the most noticeable effect on the flutter speed for four carbon-epoxy plies laminated into a square panel. A clamped panel has the lowest flutter speed regardless of the ply lay-up and the compressive load applied. Panels with free edges exhibited the highest flutter speed, indeed the flutter speed was beyond the incompressible flow model used for the air. The compressive loads typically had a negative effect, save for one case involving a simply-supported panel where a compressive load less than the buckling load has a stabilizing effect. At buckling, the panels were found to be unstable at simulated speeds.