The impact dynamics of a water droplet on a flexible substrate is useful for designing pesticide sprays and understanding insects flying in rainfall. We experimentally analyze the impact dynamics of a microliter water droplet on a superhydrophobic cantilever beam for Weber number in the range of 30–76. A thin copper sheet was coated with a commercial coating to render it superhydrophobic and high-speed imaging was used for visualization. During the impact, the spreading droplet converts its inertial energy into surface energy and elastic energy of the substrate. While retraction of the contact line, the latter energies convert to the kinetic energy of the droplet, and the droplet could bounce off the deforming cantilever beam. The characteristics timescales of droplet and cantilever beams are varied by changing the droplet diameter and impact velocity, and beam length, respectively. We show that the overall system dynamics, i.e., bouncing of the droplet and oscillations of the cantilever, is dependent on the interplay of these two timescales. A spring-mass system has been used to model this coupling and to explain the experimental observations. These findings can help to design systems to achieve desirable contact time, droplet rebound kinetic energy, energy transfer to the cantilever beam, and the droplet spreading diameter.

中文翻译：

---

在弹性的超疏水悬臂梁上弹跳液滴

水滴在柔性基材上的冲击动力学对于设计农药喷雾剂和了解在雨中飞翔的昆虫很有用。我们通过实验分析了微疏水水滴在超疏水悬臂梁上的韦伯数在30–76范围内的影响动力学。薄铜板上涂有商用涂料以使其具有超疏水性，并使用高速成像进行可视化。在撞击过程中，散布的液滴将其惯性能量转换为基材的表面能和弹性能。当接触线缩回时，后者的能量转换为液滴的动能，并且液滴可能从变形的悬臂梁上反弹。液滴和悬臂梁的特征时间尺度通过分别改变液滴直径和冲击速度以及束长而变化。我们表明，整个系统动力学，即液滴的弹跳和悬臂的振动，取决于这两个时间尺度的相互作用。弹簧-质量系统已用于对该耦合进行建模并解释实验观察结果。这些发现可以帮助设计系统，以实现所需的接触时间，液滴回弹动能，将能量转移至悬臂梁以及液滴散布直径。弹簧-质量系统已用于对该耦合进行建模并解释实验观察结果。这些发现可以帮助设计系统，以实现所需的接触时间，液滴回弹动能，将能量转移至悬臂梁以及液滴散布直径。弹簧-质量系统已用于对该耦合进行建模并解释实验观察结果。这些发现可以帮助设计系统，以实现所需的接触时间，液滴回弹动能，将能量转移至悬臂梁以及液滴散布直径。