Beam Shape Optimization for Power Harvesting

A problem in piezoelectric bimorph energy harvesting is to generate the most power with limits in system mass. The authors propose a new approach: to change the shape of the beam to concentrate the strain in sections of the beam where it can contribute the most to transduction. A vibration model of beams with non-uniform width is developed and validated with shaker table tests. Three beams with different shapes are tested over a wide band, encompassing the lowest two modes of vibration. An optimal beam shape is calculated using a heuristic optimization code and the attributes of this optimal beam are discussed. Then, beam shapes are optimized to allow for increased base excitation and constrained by maximum root strain. Finally, the tip mass-to-beam mass ratio is studied parametrically, correlating increased transduction with increased beam mass.