Abstract
In this paper, a piezoelectric energy harvesting application on a portal frame of two-degrees-of-freedom considering a quadratic coupling between the coordinates with two-to-one internal resonance is considered. The piezoelectric material is considered as a linear device using a voltage and a charge mathematical model. The equations of motion of the system were obtained by applying the energy method of Lagrange, and the method of multiple scales is applied to find an analytical approximated solution of the equations of motion. Numerical results showed that the voltage model and a charge model have good agreement in relation to the behavior and amplitudes of displacement of the system.