Geometrical uncertainties effects on the dynamics and effectiveness of a multi-stable vibratory energy harvester

Multi-stable systems, known for having complex nonlinear dynamics, have been shown in past studies to outperform their linear counterparts when designed for operation in vibration energy harvesters. This work investigates the dynamics and performance of a multi-stable electromagnetic energy harvesting device. The objectives are to enhance the levels of generated power and evaluate the useful bandwidths for the various modes of stability. Nonlinearity is introduced through a set of inclined springs and strongly influenced by the geometric parameters, as the shape of the potential energy curves can be adjusted by the selection of these properties. The effect of the geometric parameters’ uncertainties on the potential energy as a result of imperfections in manufacturing and installation, and the performance of the proposed harvester, is examined. A nominal tri-stable configuration is considered, and the sensitivity of the system to input design uncertainties is explored. The system’s response bifurcation diagrams and dynamical characteristics as well as the power output under up- and reverse-sweeping excitations are also reported. It is shown that the overall response and effectiveness of the nominal multi-stable harvester may drastically change in terms of resonance regions, periodicity of the motion, and levels of harvested power. A series of mono-stable and bi-stable harvesters arise due to the presence of geometrical uncertainties.