Characteristics of a tri-stable piezoelectric vibration energy harvester by considering geometric nonlinearity and gravitation effects

Piezoelectric energy harvester (PEH) with tri-stable potential wells has attracted considerable attention and has been studied in recent years. However, the influence mechanism of the geometric nonlinearity (GNL) and the gravitation effect (GE) on the equilibrium solution bifurcation, potential energy function, and dynamic characteristics of such device remains uninvestigated. In this paper, a global nonlinear distributed-parameter model by considering the GNL and GE of the tri-stable PEH is originally established. The effects of the GNL and GE on the equilibrium solution bifurcations and potential energy function in the parameter's space are firstly identified. It is found that the tri-stable PEH has a potential energy function with asymmetric potential wells that are not observed in the previous works. The influence mechanism of the asymmetric potential wells caused by the GE and GNL on the dynamic responses and the effective bandwidth of the tri-stable PEH are numerically analyzed. A prototype of the tri-stable PEH is manufactured and is subsequently used to validate the theories by experiments. The results indicates that the derived model by considering the GNL and GE has high accuracy, and the tri-stable PEH with asymmetric wells can not only enhance the dynamic response outputting at lower base excitation but also broaden the effective bandwidth. (C) 2019 Elsevier Ltd. All rights reserved.