In this paper, stochastic resonance (SR) is exploited within a tristable electromechanical coupled system to enhance energy harvesting. Assuming that the eective capacitance of the piezoelectric element can be neglected, the coupled electromechanical equations are converted to a secondorder stochastic dierential equation. Using the adiabatic approximation and the linear response theory, the spectral amplification of the equivalent tristable mechanical system is obtained to characterize the SR. It is observed that the spectral amplification exhibits a maximum as a function of the nonlinear stiness coecients and noise intensity. That is, both parameter-optimized SR and traditional SR are found in this system, which can be used to amplify the amplitude of the system response and enhance the performance of nonlinear vibration energy harvesting. Moreover, the eciency in power conversion and the RMS voltage obtained under the SR eect are much higher than those harvested under ambient random vibration alone. The theoretical results are well verified through the numerical simulations of the original electromechanical coupled system.

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