Application of the meta-substrates for power amplification in rotary piezoelectric energy harvesting systems: Design, fabrication and testing

Abstract

In this paper we numerically and experimentally investigate a new proposal of utilizing the auxetic meta-structure concepts to enhance the efficiency of piezoelectric energy harvesters in rotating systems. The proposed energy harvester is designed to be installed on the freight train axel to provide necessary power for the self-powered sensors. The harvester is a resonator consists of a cantilever beam with a tip mass and a piezoelectric patch mounted on its latticed substrate. Three various auxetic patterns are suggested and implemented on the base of the cantilever in order to enhance the harvested powers. The efficiency enhancement of the suggested concepts is compared with a conventional plain resonator. In order to optimize the geometrical parameters of the auxetic patterns and investigate the efficiency of various resonator’s output power, the finite element modeling (FEM) is employed. Maximum output powers according to the optimum electrical resistance and resonance frequency are achieved. Also, the effects of different PZT types on the extracted energy are taken into investigation. Two different substrate materials (aluminum and steel) are used in the fabrication of resonators. The​ numerical models are validated by experimental results in the rotating speed at the range of 6–7 Hz, which is tuned to the operational rotational frequency of the freight train axles. It is shown that for Auxetic-I, Auxetic-II, and Auxetic-III, the magnification factors are 3.28, 2.5, and 2.14 are achieved for the aluminum substrate. These factors are 3.0, 2.6, and 2.3 for the steel resonator, respectively. The experimental results show that the auxetic resonators are able to considerably enhance the efficiency of rotary energy harvesting systems.