Piezoelectric beam with non-uniform thickness for vibration energy harvesting

This paper presents the design, test and analysis of a thickness non-uniform piezoelectric beam for impact vibration energy harvesting. The piezoelectric beam has three evenly spaced rectangular grooves of identical size, and three identical rectangular piezoelectric patches. Each piezoelectric patch has the same central position as its corresponding groove, and the three piezoelectric patches are connected in parallel electrically. Experiments show that the maximum output power is approximately 48.5 μW at the excitation frequency of 15.1 Hz and acceleration of 1 g(rms), and under the constant excitation acceleration of 1 g(rms), the working bandwidth is found to be around 5 Hz in which the maximum output power is 263.9 μW. Comparisons are made to conventional uniform piezoelectric beam both experimentally and theoretically. It is found that the proposed non-uniform piezoelectric beam has much better energy harvesting capability than conventional uniform one.