Energy harvesting from an L-shaped structure, formed by two beams and corner and end masses, is investigated with the objective of expanding the bandwidth of the frequency range over which energy can be harvested. The structure is excited in a direction that yields the most uniform strain distribution along its main beam. The length of the auxiliary beam is varied to determine its effect on the level and breadth of the frequency range over which energy can be harvested. Results from experiments having different geometries are presented and discussed. It is determined that the frequency range over which energy can be harvested from such structures is much larger than levels harvested when using a cantilever beam. The experiments also show that L-shaped structures harvest more power when the length of the auxiliary beam is increased. On the contrary, the power density of the L-shaped structure is much smaller than that of the cantilever beam. The ability to control the bandwidth of frequency over which energy is harvested through proper adjustment of beam lengths is demonstrated.

The performance of a vibration energy harvester consisting of a beam with a water-filled container as the tip mass is investigated. Particular attention is paid to the capability of this system to harvest energy over a broader range of frequencies compared to the traditional beam with a solid tip mass system. The broadening is due to geometric, inertial, damping, flow nonlinearities, or a combination of them. These nonlinearities cause energy exchange between the system's modes through internal resonances leading to nonlinear periodic, or periodically or chaotically modulated responses over a relatively broad range of excitation frequencies. The results show an output voltage response that has two or more resonance peaks in comparison to the traditional harvester, which has only one peak near the resonance frequency. The system's parameters including the excitation frequency and amplitude and the water depth to container diameter ratio can be used to control the frequency bandwidth over which energy is harvested.