Aeroelastic study of bistable composite airfoils

A bistable airfoil with the actuator system and the aerodynamic loads coupled to the structure is designed to understand the aeroelastic characteristics of the system. The bistable flap consists of a stack of six bistable prestressed buckled laminates with the plates having dimensions of 100 × 100 mm made from Hexcel 913 glass fiber. The bistable plates attached to a spar situated at 85% chord on the rotor blade. The foam tape placed between each of the plates at the trailing edge making the airfoil weather tight. The bistable plate spar is parallel to the direction of motion of the moving crosshead of the test machine. For the flap to be in equilibrium without any actuator input, the sum of the work done on the structure by the aerodynamic loads W_f and the work done on the aerodynamic loads by the structure W_b is zero. The modulus function shows that the work needs to be done on the structure to rotate the flap in either direction from an equilibrium point whereas the work done on the aerodynamic loads is dependant on direction.