Knowledge Bank

Vibration energy harvesting is an increasingly viable energy source to provide for our energy dependent society. Researchers have studied systems ranging from civil structures like bridges to biomechanical systems including human motion as potential sources of vibration energy. In this work, a bench-top system of a piecewise-linear (PWL) nonlinear vibration harvester is studied. While current nonlinear harvester designs show decreased performance at certain excitation conditions, this design overcomes these issues while also still maintaining the performance of a linear harvester at resonance. A similar idealized model of the harvester was previously studied numerically, and in this work the method is adjusted to handle physical systems to construct a realistic harvester design. With the physically realizable harvester design, the resonant frequency of the system is able to be tuned by changing the gap size between the oscillator and mechanical stopper, ensuring optimal performance over a broad frequency range. In this investigation, the physical system was excited at various frequencies and gap sizes using an electromagnetic shaker. The system dynamics and the displacement transmissibility were then monitored using laser displacement sensors. These results were then compared to the numerical simulation created in MATLAB, illustrating the design's effectiveness. The investigation showed for the first time that the results measured from the physical PWL system followed the expected behavior from the computational tool, although as expected there was some error present in the computational prediction when compared to the physical nonlinear system.