Improving the performance of a piezoelectric energy harvester using a variable thickness beam

Abstract

In recent years, researchers have shown a growing interest in the possibility of harvesting mechanical energy from vibrating structures. A common way to proceed consists of using the direct piezoelectric effect of a bimorph cantilever beam with integrated piezoelectric elements. Several studies focused on the development of analytical models describing the electromechanical coupling. Historically, most of these models have been limited to simple structures such as a constant cross-section cantilever beam harvester. This paper studies the effect of a variable thickness beam harvester on its electromechanical performance. A semi-analytical mechanical model was developed using Rayleigh-Ritz approximations with a trigonometric functions set. The model was next validated by a finite element (FE) modeling. Numerical simulations were then performed for different beam slope angles in order to find the optimum for a given maximal strain across the piezoelectric elements. For the case under study, it is shown that tapered beams lead to a more uniform strain distribution across the piezoelectric material and increase the harvesting performance by a factor of 3.6.

Optimization of nonlinear structural resonance using the incremental harmonic balance method

“…In the past years, shape optimization has also been a growing topic in the field of energy harvesting. Dietl and Garcia used optimization techniques to find the optimized shape of a beam with non-uniform width to improve the power output [33].…”

Strategies for Wideband Mechanical Energy Harvester

“…The efficiency of this converter depends on its mechanical and electrical losses and also its good impedance matching with the mechanical source and electrical load. Many approaches have been developed in order to improve the efficiency of this converter, these approaches depend mainly on the type of the converter, most of them are linked to the system size and the vibration source characteristics [3][4][5].…”

Synchronicity and pure bending of bimorphs: a new approach to piezoelectric energy harvesting

“…Often researchers have extended the vibrating beam by adding inert materials, extensions and extended seismic masses [12,13], with the intent of increasing the bending moment applied at the tip of the beam. The fabrication of more complex beams with varying thickness was also proposed to increase the strain uniformity and thence energy harvesting performance [14]. Air-spaced piezoelectric cantilevers have also been offered as an alternative to conventional bimorphs with the advantage of producing, if well designed, higher voltages and more uniform strain [15].…”