A Dual Piezoelectric Vibration Energy Harvester With Controllable Gap Size Using Piecewise Nonlinearity

For the past decade, vibration energy harvesting has gained increasing interest. Numerous approaches have been developed to capture unused energy from physical vibration sources, such as ocean waves, buildings and bridges. This paper introduces and evaluates a dual piecewise-linear (PWL) piezoelectric energy harvester design. A prior study involving a single piezoelectric cantilever beam with a mechanical stopper demonstrated that optimizing the gap size could enhance energy generation. This work replaces the mechanical stopper with a second piezoelectric cantilever beam to further improve the performance of PWL piezoelectric harvesters. A new two-degree-of-freedom model is proposed and analyzed both computationally and experimentally. Moreover, an enhanced methodology is employed to identify system dynamics from experimental measurements. A simple controller is created and implemented to experimentally validate the computational model. The results demonstrate improved overall performance and a broader operating frequency range for the proposed energy harvester.