Adhesive interactions between soft materials are prevalent in both biological systems and various engineering applications, including soft robots, flexible electronics, and antifouling coatings. Many studies have demonstrated that cavitation and fingering instabilities emerge at the adhesive interface between rigid objects and soft films, owing to the geometric attributes of the contact region. However, in the context of peeling configurations, defining the geometric features is challenging, resulting in relatively scant exploration of interfacial instabilities. Hence, the modulation of instability patterns during the peeling process of a flexible plate from a thin elastic film, alongside the consequential effects on mechanical responses, remains poorly understood. To elucidate the mechanisms underlying interfacial instability during peeling process and its impacts on peel-off force, we use finite element methods to simulate the evolution of interface separation. Consistent with previous experimental observations, we find that the interfacial instability will occur when the bending stiffness of the flexible plate is bigger than a critical value. We show that the interfacial instability is mainly induced by the competition between the adhesion energy and the strain energy of the film, and the incompressibility of the thin film is critical for the appearance of the interfacial instability. Combining theory and finite element simulation, we propose the scaling laws for the critical peel-off force for stable and unstable peelings, respectively, and show that the critical peel-off force will decrease when the interfacial instability occurs. Finally, we demonstrate that weakening the tangential adhesion strength and loosening the constraints between the film and the rigid substrate effectively suppress fingering instability. Collectively, our findings elucidate the pivotal factors influencing interfacial instability, offering invaluable insights for the design of structures or systems involving soft materials.

中文翻译：

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从弹性薄膜剥离柔性板时利用界面不稳定性


软材料之间的粘合相互作用在生物系统和各种工程应用中普遍存在，包括软机器人、柔性电子产品和防污涂层。许多研究表明，由于接触区域的几何属性，刚性物体和软膜之间的粘合界面会出现空化和指状不稳定性。然而，在剥离配置的背景下，定义几何特征具有挑战性，导致对界面不稳定性的探索相对较少。因此，人们对柔性板从弹性薄膜剥离过程中不稳定模式的调节以及对机械响应的相应影响仍然知之甚少。为了阐明剥离过程中界面不稳定的机制及其对剥离力的影响，我们使用有限元方法来模拟界面分离的演变。与之前的实验观察一致，我们发现当柔性板的弯曲刚度大于临界值时，就会出现界面失稳。我们发现界面不稳定性主要是由薄膜的粘附能和应变能之间的竞争引起的，薄膜的不可压缩性对于界面不稳定性的出现至关重要。结合理论和有限元模拟，我们分别提出了稳定和不稳定剥离的临界剥离力的标度定律，并表明当界面不稳定发生时，临界剥离力会减小。 最后，我们证明削弱切向粘附强度并放松薄膜与刚性基材之间的约束可以有效抑制指状不稳定性。总的来说，我们的研究结果阐明了影响界面不稳定性的关键因素，为涉及软材料的结构或系统的设计提供了宝贵的见解。