Frequency Domain Solution of a Piezo-aero-elastic Wing for Energy Harvesting

Abstract

Multifunctional structures are pointed out as a future breakthrough technology for Unmanned Air Vehicle (UAV) design. These structures can perform tasks additional to their primary functions. Based on the concept of vibration-based energy harvesting, the structure (lifting surfaces) of a UAV can perform the additional function of providing electrical energy by converting aeroelastic vibrations to electricity. In this paper, frequency-domain piezo-aero-elastic modeling of a cantilevered plate-like wing with embedded piezoceramics is presented for energy harvesting. The electromechanical finite-element plate model is based on the Kirchhoff assumptions and a resistive load is considered in the external circuit. The subsonic unsteady aerodynamic model is accomplished with the doublet lattice method. The electromechanical and the aerodynamic models are combined to obtain the piezo-aero-elastic equations, which are solved using a modified P-K scheme. This way the evolution of the aerodynamic damping and the frequency of each mode is obtained with changing airflow speeds for a given load resistance. Piezo-aero-elastically coupled frequency response functions (voltage, current and electrical power as well relative tip motion) are defined for a given airflow speed and load resistance. Hence the piezo-aero-elastic evolution can be investigated under several different conditions. A procedure is also presented in order to obtain the optimum load resistance (for maximum power and for maximum damping) for a given airflow speed.