The design, fabrication and analysis of a cantilever-based tensile-mode nonlinear piezoelectric energy harvester

In this paper, a cantilever-based tensile-mode piezoelectric energy harvester is proposed. In contrast to a bending mode, the tensile mode enables a uniform strain distribution within the piezoelectric material. This stands in contrast to the strain concentration at the fixed end of a typical cantilevered design. The proposed design comprises a two-segment cantilever beam and an elastic PVDF film that are interconnected. The PVDF film undergoes pre-stretching to guarantee that the harvester maintains a state of tension rather than compression during excitations, as the film is not capable of withstanding compressive forces. The theoretical model of the proposed harvester is derived and validated via experiments. Due to the geometric nonlinearity of this mechanism, a highly nonlinear hardening effect is observed in the simulation and experiments. The effects of different parameters, including preload, dimensions of the elastic beam, tip mass, and excitation accelerations, are explored. The optimal configuration can provide a maximum peak power output of 1827 μW.