This work studies a forced generalised Liénard oscillator with $\phi^{8}$ potential with order 8 dissipation. The fixed points and their stability have been analysed for autonomous and non-dissipative Liénard oscillator. The system can exhibit three, five or seven fixed points and the corresponding stability diagram is checked and analysed. The effect of restoring parameters on the potential is also studied. Periodic, multiperiodic and chaotic monostable and bistable attractors and their coexistence have been checked through the bifurcation diagram, Lyapunov exponent, phase space and Poincaré section using the fourth-order Runge–Kutta algorithm. The results obtained by the analytical methods are validated and complemented by the numerical simulations.

This work concerns the modelling of the dynamics of polarisation of a centrosymmetric material subjected to an amplitude-modulated excitation (AME). The dynamic equation obtained for the polarisation is the Duffing equation with nonlinearities of orders 3 and 5. With the multiple scale method, the nonlinear resonances are studied. Periodic, multiperiodic, quasiperiodic and chaotic behaviour have been checked using the bifurcation diagram,Lyapunov exponent, phase space, Poincaré section and vibrational resonance using the fourth-order Runge–Kutta integration algorithm. The effects of various parameters of polarisation are analysed and very interesting results are obtained. The results obtained by the analytical methods are validated and complemented by the numerical simulations.