Numerical analysis and experimental verification of broadband tristable energy harvesters

This paper analyzes the dynamic characteristics of broadband tristable energy harvesters to reveal their response mechanism via a bifurcation diagram, the corresponding frequency spectral analysis and the phase portrait topology. The bifurcation diagram of response voltages shows that tristable energy harvesters orderly undergoes singly periodic intrawell oscillation, singly periodic interwell oscillation, triply periodic interwell oscillation, singly periodic interwell oscillation, double-periodic interwell oscillation, chaotic oscillation, singly periodic interwell oscillation, multi-period oscillation, and finally enters into chaotic oscillation range, as the increase of the excitation amplitude. The frequency spectral analysis demonstrates that sub-harmonics and super-harmonics numerically and experimentally exist in the response voltages of tristable energy harvesters. In addition, it is found that both the first harmonic and the third harmonic are main frequency components in the response voltages.