Dramatic effect of fluid damping on the performance of a nonlinear M-shaped broadband energy harvester

This work aims to demonstrate the detrimental effect of fluid damping on the bandwidth of a flexible nonlinear energy harvester and thereby further enhance the performance by minimizing nonlinear damping. A vacuum setup has been introduced to conduct nonlinear base excitation experiments at different air pressure levels in an effort to control the quadratic (velocity-squared) damping coefficient. It is shown that reduced air pressure substantially enhances the frequency bandwidth for primary resonance excitation. The empirical electromechanical model is modified to express the fluid damping in terms of fluid pressure and validated experimentally for different excitation levels.