Nonlinear dynamics and control of ripple formation in abrasive water-jet cutting

We show experimentally that there are two sources of ripple formation in abrasive water-jet cutting. Ripples can be triggered externally by periodic pressure oscillations, e.g. due to the pump, or they can be generated intrinsically. The latter is due to a spontaneous front instability as described by the nonlinear evolution equations for the cutting front. By including oscillatory motion of the beam, or equivalently oscillations in the beam intensity, we are able to explain on the one hand resonance phenomena between intrinsic and external ripple-formin mechanisms. On the other hand the same approach leads to a strategy for ripple suppression if the corresponding frequencies are well separated.