Effect of major factors on broadband natural frequency energy harvesting for rectangular and L- shaped cantilever harvesters

A small amount of natural frequency deviation extremely decreases the output power. So, a multi-mass single harvester (bending harvester) was utilized to enlarge the bandwidth of the natural frequency. We constructed three models to study the effect of increasing the concentrated masses on increasing the bandwidth natural frequency. We used Finite Element Metho (FEM (COMSOL to model and simulate the three models. Moreover, we constructed an L-shaped harvester with concentrated masses to compare the rectangular harvester with concentrated masses. The results prove that increasing the number of concentrated masses increases the output power and broadband natural frequency. Moreover, the results indicate that the harvester cantilever with concentrated masses gives more output power and broadband than the L- shaped harvester for the same volume. Also, our research studied the harvester parameter effects on the output power. This study found that the increase in beam length and mass height increases the output power while the increase in piezoelectric thickness and damping ratio decreases the output power and bandwidth frequency. We validated our proposed model through a comparison with others’ preceding experimental results and it showed a good agreement. The harvester with a high width/length ratio gives a larger wideband natural frequency.