On the advantage of a bistable energy harvesting oscillator under band-limited stochastic excitation

Oscillation-based linear energy harvesters are often excited by random, band-limited, slowly varying forces. When the excitation bandwidth is limited such that natural frequencies of electromechanical energy harvester are not excited, linear devices lose their efficiency, and nonlinear structures with negative stiffness can be used to enhance the conversion efficiency by performing frequency up-conversion. It is shown here that nonlinear, bistable oscillators perform considerably better than their linear counterpart under band-limited excitation, in certain regions. This is contrary to commonly modeled, wideband, or white noise excitation, where nonlinear potential has no or little effect on the energy output. A sharp increase in performance is observed for band-limited random excitation along a well-defined region in the input-level and bandwidth plane. Having defined this region, the harvesting device can be adaptively tuned in order to keep the power output levels high. The results of simulated, partially analytical, and experimental studies are compared and analyzed to obtain cross-validation.