Effect of stochastic excitation on sub-harmonic solutions in a bistable energy harvester Americo Cunha Jr 1,a) , Grzegorz Litak 2 and Piotr Wolszczak 2 1 Rio de Janeiro State University, Rua S˜ ao Francisco Xavier, 524, Rio de Janeiro, RJ 20550-900, Brazil 2 Lublin University of Technology, Nadbystrzycka 36, Lublin 20-618, Poland a) Corresponding author: americo.cunha@uerj.br Abstract. Broadband frequency energy harvesting systems are based on nonlinear resonators. Ambient kinetic energy is trans- formed to electric energy by a piezoelectric patch installed on the elastic beam. In this paper we study a bistable energy harvester consisted of the resonator with some nonlinearities induced by magnets. The system is excited with the combined effect of the frame harmonic and stochastic motions. Starting from initial conditions with minimum energy we observe considerable improve- ment of performance of the system in the presence of stochastic excitation component. Our initial calculations clearly indicate the existence of stochastic bifurcations in that system. Introduction The piezoelectric Energy Harvesting (EH) from ambient vibration sources are considered as an important application for distributed energy supply in case of structural health monitoring systems and/or small electric energy devices. A device for EH is usually consisting of the cantilever beam as a mechanical resonator with a piezo-ceramic patch as a energy transducer. During the beam excitation strains occur in the deflected beam resulting by voltage output on the electrodes. The nonlinear potential of the beam induced by magnets is dedicated to the frequency broadband effect to optimize the energy harvesting procedure [1, 2, 3]. FIGURE 1: Schematic of the energy harvester with kinematic excitation through the frame [6]. The EH system which is under investigation was proposed by Erturk et al. [1], is the piezo-magneto-elastic beam, driven by a noise-disturbed rigid base (frame) movement, that is illustrated in Figure 1.