Efeito da incorporação de minimolas NiTi superelásticas no amortecimento estrutural: aplicações em atenuação passiva de pás de aero gerador.

Abstract

The current global energy environment has driven the growth of investments in renewable energy sources, such as wind energy. A notable feature of the development of wind turbine technology is the vibrational problem of the blades which, in addition to causing fatigue, can also compromise output power. Researchers have traditionally been using various concepts and strategies of vibrational control for these structures, but in most cases, these forms of control add stiffness and mass to the system and in some cases, consume electrical energy for operation. In this circumstance, implementing a vibrational control strategy that achieves a significant reduction in response amplitude and, at the same time, doesn’t add mass and additional rigidity is of great contribution to the wind industry. This work investigates the incorporation of mini-springs fabricated with superelastic shape memory alloys (SMA-SE) in the passive control of vibrations in flexible structures. For this purpose, helical NiTi Superelastic mini-springs with different geometric configurations (closed and sectioned) were acquired. A Dynamic Mechanical Analyzer (DMA) was used to carry out thermo-mechanical characterization of the SMA-SE springs in a quasi-static test with controlled temperature. Furthermore, a thermal analysis was carried out using a Differential Scanning Calorimetry (DSC) to obtain the phase transformation temperatures. Besides that, modal tests with the springs in a one degree of freedom system (1DOF) were performed. The results show a large damping capacity, with a reduction in displacement amplitude of 40%. Lastly, three operating conditions were tested experimentally, using a 160 W AIR Breeze generator manufactured by the company Southwest Windpower, Inc., in laboratory environment, with and without the incorporation of the mini-springs SMA-SE in the blades of this wind turbine. The implementation of the mini-spring provided a reduction of 12 dB in the vibrational intensity, without considerably altering the stiffness of the blades and with an increase of 0.43% in the mass of the latter, which was observed to be irrelevant to the system.