Increase of Flutter Speed using Variable Stiffness Concepts in Composite Plates

This contribution is devoted to seek the potential of variable stiffness concept in composite laminates subjected to a flow passing over their top surface. In practice, this problem occurs in the wings of jet fighters or space shuttles, where the airspeed may reach up to five times the speed of sound, or Mach 5. The theory used here to model the aerodynamic force (pressure), namely Piston theory, is generally valid for low supersonic Mach numbers. The structural model of the laminate is based on the third-order shear deformation theory. The solution of the eigenvalue problem of the coupled “structural” and “aerodynamic” models gives the flutter speed. Considering that flutter is a dynamic instability of the laminate, the vibrations due to aerodynamic forces before this speed can be regarded as dynamically stable.