Dynamic response of equation of motion (Eqs. (11)–(12)) using second order perturbation and numerical integration. Parameters are: $α0,1 = 2/75$⁠, $α0,0 = 2/3$⁠, $α2,0 = 1/4$⁠, $α3,0 = -1/24$⁠, $e1 = 0.1$⁠, $ψ1 = 0$⁠, $α2,1 = 0$⁠, $μ = 0.0082$⁠. Important regions of solutions are marked with (1) through (4). (Stable perturbation solution: solid line, unstable perturbation solution: dashed line, numerical integration: circles, linear solution: dashed-dotted line.)