Friday, May 4, 2012
Adaptive Aeroelastic Tailoring using Variable Stiffness Approaches
Paolo Ermanni, Professor, ETH Zurich
Bending-twist coupling is one of the most decisive properties affecting the aeroelastic behaviour of aerostructures as wings or rotor blades. In this context, semi-active structural elements based on variable stiffness represent a promising approach to the solution of the conflict of requirements between load-carrying capability and shape adaptivity in morphing structures. In this talk, a structural concept with adaptive bending-twist coupling aiming at a broad adjustment range of coupling stiffness while maintaining high flexural rigidity is investigated. The basic concept is relying on layers with variable shear stress transfer, controlled by temperature or electric fields. In particular, we are investigating novel forms of direct electrostatic coupling. The concept of Electro Bonded Laminates (EBL) relies on the combination of electrostatic normal forces and friction between laminate layers in order to actively control the bending-twist coupling of the system. The mechanical response is strongly dependent on the electrical properties of its polymer constitutive films in terms of dielectric and the insulating properties. Multilayer polymer configuration is considered as a possible answer to this need and it is put forward together with the electric model and the relatively high frequency experimental evidence of the proposed solution.