On the applicability of HAM to seek periodic solution for truly nonlinear oscillator

Abstract

Homotopy perturbation method (HPM) is claimed to be a simple analytic approximation method suitable for solving nonlinear differential equations. It assures solution series convergence by transferring the nonlinear problem into a number of linear sub-problems. A differential equation which is really nonlinear oscillator is considered for obtaining periodic solution using the HPM. To examine the adequacy of HPM, the phase diagram made from the approximate solution is studied with respect to the actual phase diagram.