Energy Harvesting From Controlled Buckling of a Horizontal Piezoelectric Beam

Abstract

A piezoelectric vibration energy harvester is designed to generate electricity under the weight of passing crowds. The piezoelectric beam buckles to a controlled extent when the device is stepped on. The device is a seven bar mechanism. The upper and lower bars as well as the lateral links are rigid. The middle horizontal beam is a bimorph piezoelectric beam. Damages to the piezoelectric beam are avoided by constraining its axial deformation. This constrain is implemented by limiting squeezing of the mechanism. When a person moves over the mechanism or steps off the devices it causes the bimorph to buckle or return to the unbuckled condition. The transitions result in vibrations of the piezoelectric beam and thus generate energy. In this paper, the energy harvester is analytically modeled. The electro-mechanical coupling and the geometric nonlinearities have been included in the model for the piezoelectric beam. The design criteria for the device are discussed. It is demonstrated that the device can be realized with commonly used piezoelectric patches and can generate hundreds of milliwatts of power. A three part beam is also investigated. The effect of design parameters on the generated power and required tolerances are illustrated. The proposed device could be implemented in the sidewalks producing energy from the weight of people passing over it. Other possible applications are portable smart phones chargers and shoe hill energy harvesting. Dance floor of a club is another applicable example for using this harvester. The main advantage of using horizontal configuration instead of a vertical arrangement is the ease of placement in the pavements.