Dynamics and energy harvesting of a flow-induced snapping sheet with nonuniform stiffness distribution

Energy harvesting through periodic snap-through of a buckled sheet has recently gained considerable attention because of its potential applications in energy harvesting in low incoming flow. Although the snapping dynamics of uniform buckled sheets has been extensively studied, the present work focuses on the energy harvesting and dynamics of a nonuniform snapping sheet with both of its ends clamped in a channel flow. The analysis reveals that the sheet undergoes periodic snap-through oscillations, with its rear half consistently serving as the main contributor to effective energy harvesting, and the potential energy contributing significantly more than the kinetic energy. Varying the stiffness difference ΔEI* shows that increasing the stiffness of the rear part and decreasing that of the fore part shifts the deformation wave toward upstream and enhances the snapping amplitude of the fore part, optimizing energy extraction. At a length compression ratio ΔL* = 0.3, the maximum potential energy is observed for ΔEI* = 1, and the total energy peaks at ΔEI* = 2. The study also identifies an optimal ΔL* = 0.4 that maximizes both total and potential energies, and triples the potential energy in comparison with ΔL* = 0.1. However, the enhancement of nonuniformity disappears at ΔL* > 0.3 for the total energy and ΔL* > 0.2 for the potential energy. These findings provide insights to aid optimization of the design and performance of snapping sheet energy harvesters.