ELECTROMECHANICAL PERFORMANCES OF DIFFERENT SHAPES OF PIEZOELECTRIC ENERGY HARVESTERS

In recent years, researchers have shown an interest in the possibility to harvest mechanical energy from vibrating structures. A common way to proceed consists of using the direct piezoelectric effect of a bimorph cantilever beam with integrated piezoceramic elements. Several studies focused on the development of analytical models describing the electromechanical coupling. However, these models were limited to simple structures such as constant cross-section cantilever beam harvester. This paper studies the effect of the harvester geometry on its electromechanical performance. A specific geometry will be of interest in this paper: a tapered beam. A semianalytical model is developed using Rayleigh-Ritz approximations and a trigonometric functions set. Numerical simulations are then performed for three different cases: a standard rectangular harvester, an equivalent mass/stiffness tapered beam harvester and an equivalent maximal strain tapered beam harvester. It will be shown that tapered beams lead to a more uniform strain distribution across the piezoelectric material and could increase the harvesting performance by 69%. Tapered beam harvesters are very interesting since they are low-cost and easy to manufacture.