A Lumped Electromechanical Model for Output Power from Partially Covered Piezoelectric Energy Harvester

Abstract

The cantilevered piezoelectric vibration energy harvesters are operated in their first mode and analysed as Single Degree of Freedom (SDOF) systems. In literature, models were developed with piezoelectric material spread over the entire length of the substrucutre beam. In cantilevered arrangement, strain in the harvester beam is maximum at fixed end and minimum at the free end. So it is not cost effective to use piezoelectric materials for full length of the substructure beam. A lumped electromechanical model for output power from piezoelectric vibration energy harvester beam with partially covered piezoelectric material is proposed. The governing equations of motion for the coupled electromechanical model are deduced using Newton's laws of motion and Kirchoff's current law. A novel method using a correction factor to find equivalent stiffness properties of proposed harvester beam is studied, thereby equations for output power from the harvester are deduced. The model is developed considering transverse harmonic base excitation and linear system parameters. Experiments are performed to validate the results from electromechanical model. The performance of harvester is investigated for different tip masses. The analytical model results and experimental measurements have shown good agreement in resonance frequency, relative displacement and output power.