Nonlinear dynamics and performance evaluation of an asymmetric bistable energy harvester with unilateral piecewise nonlinearity

Due to the snap-through characteristics and broadband response, bistable energy harvesters (BEHs) have attracted significant attention. Previous studies revealed that asymmetry in potentials has an adverse impact on performance. To broaden the response bandwidth, a stopper is introduced and positioned at the side with a deeper potential well to realize unilateral piecewise nonlinearity, and this paper emphasizes the system's nonlinear dynamics and output performance. Bifurcation diagrams and basins of attraction are utilized to study the system's local and global dynamics under harmonic excitations. Numerical results illustrate that a proper collision gap between the stopper and beam could enable the system to realize large-amplitude oscillation within a wider frequency range, and this phenomenon is closely related to excitation amplitude and collision stiffness. Under stochastic excitation, numerical output reveals that there is an optimal collision gap for low to moderate excitation intensities, while the introduction of a stopper degrades the performance when the noise intensity is large enough. Regarding the collision stiffness, the collision gap and noise intensity should be clarified to examine its influence on performance. In general, this numerical study provides an effective strategy, but still less be explored, to enhance the performance of asymmetric BEHs.