On the interaction of a cavitation bubble with an carbon fiber composite elastic plate

Abstract

We experimentally and numerically investigated the interaction between a spark-induced bubble and an elastic plate. We focused on the bubble dynamics and plate deformation, which influenced by different boundary thickness h ($0.5<$ h $<2.0\mathrm{mm}$) and initial stand-off distance $\gamma$ ($0.5<\gamma <2.0$). The elastic plate is made of carbon fiber layers, attached to a gum base of 0.1 mm thickness. A transient cavitation bubble generated by the fast electric discharge between two immersed electrodes, and the bubble maximum radius is 20 mm. We used high-speed camera to capture the bubble motion and the boundary motion at the simultaneously. We also conducted numerical simulations with the immersed boundary method, taking into account fluid compressibility and the boundary motion. The research results demonstrate that the amplitude of plate deformation directly affects the dynamic behavior of the bubble. The plate deformation along vertical direction is periodic in time, and the difference between the free end and the center ($\lambda$) is almost an approximate wave function. A dimensionless parameter $\Delta \zeta$ is proposed to measure the frequency and amplitude of boundary oscillations. The trend of $\Delta \zeta \left(t\right)$ over time satisfies the wave equation, which shows that the plate undergoes a similar harmonic vibration after the force is applied. The function can be viewed as a superposition of an external force (from the flow field) induced oscillation (${\zeta }_1$) and a self-inertial oscillation (${\zeta }_2$). We found that increasing the initial distance $\gamma$ mainly reduces the maximum amplitude of the external force-induced oscillation ${\zeta }_1$. Increasing the plate thickness h results in a reduction of both the frequency and amplitude of the oscillation function. Some of the conclusions of this work can be applied to the design of new hydromechanics of materials.