FLUTTER OF GEOMETRICALLY-IMPERFECT SHEAR-DEFORMABLE LAMINATED FLAT PANELS USING NONLINEAR AERODYNAMICS

The dynamic instability resulting from a high-supersonic flow over a s imply supported laminated flat panel subjected to uniform in-plane edg e compression is studied. The structural model incorporates geometrica l non-linearities, transverse shear deformation, and transverse normal stress effects, and satisfies the traction-free condition on both fac es of the panel. In-plane edge restraints and small initial geometric imperfections are also considered. Aerodynamic loads based on the thir d-order piston theory are used and the panel flutter equations are der ived via Galerkin's method. The arclength continuation method is used to determine the static equilibrium state whose dynamic stability beha vior is subsequently examined. The effects of transverse shear flexibi lity, aerodynamic non-linearities, initial imperfections, and in-plane edge restraints on the stability boundaries are studied. It is observ ed that the classical plate theory generally overpredicts the critical flow speed and compressive load, and a shear deformation theory is re quired when considering panels that are flexible in transverse shear. When aerodynamic non-linearities are included, multiple flutter speeds may exist. The nature of the flutter boundary for perfect panels is d etermined by the method of multiple scales, and it is seen that the pr esence of aerodynamic non-linearities could result in the hard flutter phenomenon. Results indicate that non-linear aerodynamics is importan t for panels that are not sufficiently thin (i.e., panels characterize d by a high flutter Mach number). (C) 1996 Academic Press Limited