Improving the performance of a piezoelectric energy harvester using a variable thicknessbeam

Abstract

In recent years, researchers have shown a growing interest in the possibility of harvestingmechanical energy from vibrating structures. A common way to proceed consists ofusing the direct piezoelectric effect of a bimorph cantilever beam with integratedpiezoelectric elements. Several studies focused on the development of analytical modelsdescribing the electromechanical coupling. Historically, most of these models havebeen limited to simple structures such as a constant cross-section cantilever beamharvester. This paper studies the effect of a variable thickness beam harvester on itselectromechanical performance. A semi-analytical mechanical model was developed usingRayleigh–Ritz approximations with a trigonometric functions set. The model was nextvalidated by a finite element (FE) modeling. Numerical simulations were thenperformed for different beam slope angles in order to find the optimum for a givenmaximal strain across the piezoelectric elements. For the case under study, it isshown that tapered beams lead to a more uniform strain distribution across thepiezoelectric material and increase the harvesting performance by a factor of 3.6.