Rupture of a rubber sheet by a cavitation bubble: an experimental study

Dynamics of spark-generated cavitation bubbles near a deformable rubber sheet are experimentally investigated in this study. The transient bubble-rubber interaction is captured by high-speed photography, including the expansion and collapse of the bubble, jetting behaviors, large deformation, and rupture of the rubber sheet. The dependence of bubble behaviors and rubber response on two governing parameters (the bubble-rubber stand-off distance gamma and the rubber thickness T) are systematically studied. Firstly, the bubble collapse patterns or jetting directions are categorized into three regimes. If the bubble is initially located at a large gamma from the rubber sheet, the jet is directed towards the boundary (regime I). Unexpectedly, when the generated bubble is close to the rubber sheet, it develops a jet away from the boundary (regime III). Bubble splitting and the formation of two axial liquid jets directing in opposite directions can only be observed with an intermediate gamma (regime II). A phase diagram of the bubble behaviors is given in the gamma-T space. For a large rubber sheet thickness (e.g., T = 5mm), only a downward jet is observed. From the perspective of jet direction, the effect of such a thick rubber sheet on the bubble dynamics is similar to that of a rigid wall. Note that the jet velocity and jet width may be slightly different. Secondly, the results reveal that bubble expansion can cause the boundary to deform. The strong axial jet towards the rubber sheet can damage and even rupture the rubber boundary. A parameter range within which the bubble jetting can rupture the rubber boundary is obtained. Besides, for a thin rubber sheet (T <= 4mm), the rupture is more likely to occur in regime II. For a thick rubber sheet (e.g., T = 5mm), the rupture can be seen when the jet directly impacts the rubber sheet (regime I).