I am trying to simulate a duffing oscillator. I am not sure how to read the phase diagrams I am obtaining. In the image, we can see at the top the phase diagram before the bifurcations; it has an elliptical shape and it's centred around $0,0$. In the bottom picture, we can observe how now the phase is around $-0.9$ (corresponding to $\alpha$); however, it is not a circular shape anymore. What does this entail?
phase diagram of Duffing oscillator before (top picture) and after (bottom picture) bifurcation:
Furthermore, if I keep modifying the parameters of the circuit (α, β and γ), the phase diagram keeps being the same and doesn't become chaotic. Is this the expected behaviour?
Finally, I was able to obtain this graph, but I am not sure of its meaning. Is it showing the two solutions after the bifurcation?
phase diagram of Duffing oscillator after bifurcation:
