Design and dynamics of a cantilevered bistable buckled piezoelectric beam for vibrational energy harvesting

In this paper, a novel family of low-cost, magnet-free bistable piezoelectric energy harvesters with a simple structure is designed, fabricated, and tested to evaluate their nonlinear dynamics and performance for harvesting energy from broadband vibrations. A laser-machined bistable structure, consisting of a buckled beam and two supporting beams, is employed as the host structure for constructing this energy harvester with piezoelectric transducers. The integration of buckled beams and constraints provided by supporting beams allows for the configuration of this bi-stable buckled piezoelectric beam under cantilevered boundary conditions without requiring external operation. The proposed harvester’s static mechanical properties and dynamic responses are predicted using a finite element model, while its basic dynamics are understood through a simple analytical model. The frequency-sweep results demonstrate that the proposed harvester exhibits a broadband characteristic compared to the linear piezoelectric beam with a similar configuration, and various vibration modes and their corresponding performance of energy harvesting are analyzed and characterized. The potential of this proposed harvester is explored by adjusting the geometry parameters, such as the width of the supporting beam and thickness, to alter its dynamics and energy harvesting performance. Finally, a nonlinear energy harvesting array consisting of four proposed harvesters with adjacent broadbands is fabricated to enhance overall performance, achieving a broadband width of 13.7 Hz at an acceleration of 0.75 g. The proposed method introduces a novel design philosophy for nonlinear vibrational energy harvesters.