Global optimization of excitation directions for scavenging energy based on a cross-jointed L-shape multidirectional piezoelectric energy harvester

Energy harvesting technology can collect energy from environmental vibrations, but it is still challenging because the vibration from an environment is random and the directions vary. In this study, a novel cross-coupled L-shaped vibration piezoelectric energy harvester (CL-VPEH) was proposed to collect energy from different environmental vibration directions. This CL-VPEH consists of a vertical beam and a horizontal beam joint crosswise with two laminated piezoelectric layers. Finite element analysis was performed to study the voltage output and resonant frequency. A simplified lumped mass model of CL-VPEH under excitation from an arbitrary direction was built to describe its working principle and multi-directional energy-harvesting ability. The experimental results demonstrate that the CL-VPEH shows good agreement with the numerical and analytical solutions. The experimental results validate the CL-VPEH’s multidirectional energy harvesting ability. Using the lumped mass model, the performance of the CL-VPEH under every single-direction excitation is investigated. A weak power output area is found with a frequency range of 10 Hz − 25 Hz, which should be avoided in future applications of this kind of multiple-directional excitation energy harvesting.