A nonlinear piezoelectric energy harvester with multiple auxetic unit cells

In this paper, we design and experimentally validate a new auxetic nonlinear piezoelectric energy harvester for broad working bandwidth and high power output, which combines a clamped-clamped beam with multiple rotating square unit cells. On one hand, the key structural parameter of the square rotating unit cell is adjusted to obtain desired broad working bandwidth. On the other hand, the number of the unit cells is increased to improve the power output of the energy harvester with minor influence on the working bandwidth. Therefore, based on the parameter adjustment and unit cell number increment, the proposed energy harvester can obtain both broad working bandwidth and high power output, which can solve the trade-off between these two aspects in previous auxetic nonlinear energy harvesters. Finite element analysis is performed to analyse the characteristics of the energy harvester. The lumped parameter model is utilized to predict the performance of the energy harvester, which matches well with the experimental results. In the experimental validation, under 0.3g base acceleration, the working bandwidth and power output of the auxetic nonlinear energy harvester are increased by 14% and 268%, respectively, compared with the conventional nonlinear energy harvester.