Effects of changing PZT length on the performance of doubly-clamped piezoelectric energy harvester with different beam shapes under stochastic excitation

The concept of vibratory energy harvesting has flourished in recent years as a possible alternative to provide a continuous power supply. Most work focusing on changing the configuration of piezoelectric energy harvester has concentrated on cantilevered beams at resonance using harmonic excitation. This work is mainly devoted to obtain the effects of changing PZT length on output characteristics for doubly-clamped piezoelectric energy harvester with different beam shapes under stochastic excitation. Firstly, analytical expressions of output characteristics of random excited doubly-clamped piezoelectric energy harvester are derived. Subsequently, the trends between factors that affect output characteristics and the change of beam shape or PZT length are calculated and analyzed. Finally, effects of changing PZT length on output characteristics varying with load resistance and acceleration’s spectral density for doubly-clamped piezoelectric energy harvester with different beam shapes are compared and discussed. Monte Carlo simulation and experimental results exhibit qualitative agreement with Fokker–Planck theory, showing that changing PZT length could improve output characteristics of random excited doubly-clamped piezoelectric energy harvester considerably. Besides, it also demonstrates that doubly-clamped trapezoidal piezoelectric energy harvesters under random excitation are superior to their rectangular counterparts.