Novel tunable broadband piezoelectric harvesters for ultralow-frequency bridge vibration energy harvesting

Abstract

With a nonlinear X-shaped structure connected with piezoelectric harvesters through two types of special mounting configurations (horizontal and vertical cases), novel coupled vibration energy harvesting systems are purposely constructed and investigated for exploiting nonlinearity and structural coupling effect in vibration energy harvesting. Different from concentrating on a beam harvester itself in the literature (i.e. the beneficial nonlinearity comes from the beam itself), this study focuses on exploring the nonlinear benefits that the X-shaped structure could provide, together with structural coupling effect. The novelty lies in that the coupled X-structured harvesting systems have both the advantages of the existing simple cantilevered beam harvester (harvesting power only at around the natural frequency of the beam) and the spring-mass system supported beam harvester (harvesting energy only at around the natural frequency of the supporting spring-mass system). With the proposed X-structures, the effective operation bandwidth of traditional cantilever based harvesters can be greatly enlarged and also be extended to an ultralow frequency range. This is a very special feature of the proposed X-structure based harvesting systems compared with conventionally designed cantilevered harvesters or the spring-mass supported cantilevered harvesters. The proposed devices can be regarded as advantageous versions of the cantilever-based configurations for ultralow frequency range. In addition, the X-structured harvesters can achieve very tunable harvesting bandwidth (i.e. tuning the harvesting frequency of the first peak) by adjusting several structural parameters. The experiment tests demonstrate that the proposed harvesting devices hold potentials for traffic-induced bridge vibration energy harvesting, which can be used for powering the sensors for bridge health monitoring.