“…The pendulum oscillator and some related equation have been used as a physical model to solve several natural problems related to bifurcations, oscillations, and chaos such as nonlinear plasma oscillations [1][2][3][4][5], Du¤ing oscillators [6][7][8][9][10], Helmholtz oscillations [8], rigid plates that satisfy the Johanessen performance criteria [11], transverse vibrations nonlinear of a plate carrying a concentrated mass [12], a beam supported by a double periodic axial oscillating mount [13], cracks subjected to concentrated forces [14], surface waves in a plasma column [15], coupled modes of nonlinear bending vibrations of a circular ring [16], double spin spacecraft [17], motion of spacecraft over slowly rotating asteroids [18], nonlinear vibration of clasped beams [19], the nonlinear equation of wave [20], nonlinear mathematical models of DNA [21], the nonlinear Schrödinger equation etc. There are few attempts for analyzing the equation of motion of the nonlinear damped pendulum taking the friction forces into account [22].…”