Experimental evidence of quasiperiodicity and its breakdown in the column-pendulum oscillation.

A new vibration absorbing device is introduced for large flexible structures. The phase-space of the experimental system is reconstructed via delay-coordinate embedding technique. Experimental dynamics indicates that the motion is predominantly quasiperiodic, confirming the existence of invariant tori. Within the quasiperiodic regions, there are wide windows containing intricate webs of phase-locked periodic responses. The quasi-periodic and the phase-locked responses are clearly visualized on the cover of the torus. Increasing the amplitude of the excitation, results in distortion of the invariant torus due to the resonance overlap. Which in turn renders the return maps extended from the experimental data, non-invertible. Furthermore, a burst of frequencies appear on the Fourier spectrum. This scenario is similar to many experimental observations of hydrodynamical instabilities; the break-up of the tori in these experiments is related to the onset of turbulence.