Design and study of rigid-flexible coupled piezoelectric energy harvester

Attaching a rigid frame to two cantilever plates, a compact piezoelectric energy harvester (PEH) with wide bandwidth is proposed in this paper. Three different arrangement form and section shape of the two cantilever plates, such as, symmetrical uniform section rectangle, symmetrical variable section trapezoid and anti-symmetrical variable section are designed. Considering the frame as a rigid body and the cantilever plate as a deformed body, natural frequencies, modes and output voltages of the structures are calculated using finite element software ABAQUS. It is found that the anti-symmetrical trapezoidal cantilever plate surrounded by rigid frame, has lower natural frequency, more working frequency bands in low frequency range and the highest output voltage. According to the simulation results, prototype of PEH with anti-symmetrical trapezoidal cantilever plate surrounded by rigid frame is processed and fixed to the vibration platform using custom fixture. Through sweep test, open-circuit output voltage of PEH at different frequencies is measured using oscilloscope and the first three order natural frequencies are obtained. The results meets the design requirements of multilevel natural frequency and high output voltage in low frequency range. This research provides theoretical and experimental basis for the engineering application of the PEH. (paper)