Evaluation of Analytical and Finite Element Modeling on Coupled Field Dynamics of Piezoelectric Cantilever Bimorph Harvester

As the portable electronics and wireless sensors continue to be minimized in size and power consumption, the energy harvesting from the surrounding environment has become a potential major or supplementary power source for those devices. As an energy harvesting option for converting the mechanical vibrations to the electrical energy, the structure-electricity field coupled piezoelectric materials have relatively high conversion efficiency, light weight and small size, making them preferable for wireless sensor networks and portable electronics. In this paper, the modeling work on coupled field dynamics of the piezoelectric cantilevered bimorph (PCB) energy harvester is presented, in terms of structure tip displacement and open-circuit electrical potential generated through harmonic excitation. First, a single degree of freedom (SDOF) analytical model is presented for predicting the tip displacement of the PCB structure, and then a finite element (FE) model is created to simulate the tip displacement and open-circuit voltage of the PCB structure. Then, both the analytical and finite element models are compared against the laboratory experimental results. The comparison shows that the FE model has a better agreement with the experimental result than the analytical model. Based on the evaluation, these two models could be adopted as design tools in different cases.