Stochastic Nonlinear Dynamic Characteristics Of Giant Magnetostrictive-Piezoelectric Vibration Energy Harvester

In this paper,a novel type of giant magnetostrictive-piezoelectric composite vibration energy harvester is proposed,whose self-excitation vibration can be induced by the outside stochastic excitation to improve its efficiency.Its output voltage is quasi-periodic,which means the effective utilization of the environmental random vibration energy.The nonlinear coupling dynamic characteristics of the composite vibration energy harvester subjected to stochastic excitation are studied.In this paper,the following results were obtained,they are:To use the theory of hysteresis nonlinear and partial least-squares regression method to establish the magnetic field strength and strain relationship of Terfenol-D which are under different magnetic field frequency,and the magnetic field strength and strain relations of KNN piezoelectric materials which are under different temperature.We introduce Van der Pol nonlinear differential item to explain it.To use the Hamilton principle to model the giant magnetostrictive-piezoelectric vibration energy harvester with mechanics,and the system's response equation is obtained,and the multiscale method is applied to the approximate solution of autonomous systems and nonautonomous system,and the stability of nonautonomous system are discussed.In the meanwhile,using the MATLAB mathematical software to discusse the influence of different parameters on the nonautonomous system stability.To study the giant magnetostrictive-piezoelectric vibration energy harvester under random excitation.By random maximum Lyapunov index to judge local stability of the system,using the theory of singular boundary to determine the global stability of system,and combine the response of the system steady-state probability density of joint to research the stochastic Hopf bifurcation critical condition of the system,so as to improve the stability of the system.To carry on a experiment,the experimental results illustrate he the giant magnetostrictive-piezoelectric vibration energy harvester working in good condition,when the input exciting force is the harmonic signal,it can produce harmonic current;when the input exciting force is a narrow-band random signal,it can produce approximate harmonic current;when the input exciting force is the white noise signal,it still can produce approximate harmonic current.Further studies for the giant magnetostrictive-piezoelectric vibration energy harvester has important reference value.