A new analytical approach to

In this paper, a modified harmonic balance method is used to investigate the strongly nonlinear oscillators. The approximate frequency and periodic solution for both small and large amplitude of oscillations show a good agreement with the numerical solution (considered to be exact). One of the most advantages of the presented method is its simplicity. Results found in this paper are compared with other existing solutions (obtained by several authors) and those results are more accurate than other existing solutions. The method is illustrated by examples