Abstract
A type of giant magnetostrictive-piezoelectric composite vibration energy harvester is proposed in this paper, and its stochastic nonlinear dynamic characteristics are studied. Giant magnetostrictive material is applied to induce the harvester's self-excited vibration to improve its efficiency. Nonlinear differential term is introduced to explain the hysteresis phenomena of a giant magnetostrictive material, and the fitting effect of the constitutive model on experimental data is proved by the partial least-square regression method. The nonlinear dynamic model of a giant magnetostrictive-piezoelectric vibration energy harvester subjected to stochastic foundational excitation is developed, and the stationary probability density function of the system's response is obtained. The transition sets of the system's response are determined, and the conditions of stochastic bifurcation are obtained. Numerical and experimental results show that the stochastic Hopf bifurcation occurs when the parameters varies; the output voltage is quasi-periodic, which means the effective utilization to the environmental stochastic excitation.