Mechanics of Interfacial Delamination in Deep-Sea Soft Robots Under Hydrostatic Pressure

In recent years, with the increasing demand for ocean exploration, deep-sea soft robots featuring better environmental adaptability, lighter weight, and less energy consumption relative to traditional robots have emerged. Considering that deep-sea soft robots usually contain components composed of dissimilar materials in the form of layered structures, interfacial delamination is likely to occur under extreme hydrostatic pressure, which may significantly impact robot operation. Moreover, traditional numerical methods to analyze interfacial delamination with J-integral have limitations in analyzing interfacial delamination in abyssal environments due to the hydrostatic pressure exerted on delaminated interfaces. To address this largely unexplored issue, this paper proposes a numerical method suitable for calculating the energy release rate for interfacial delamination in a film-substrate structure under hydrostatic pressure and systematically studies the factors influencing the energy release rate in deep-sea soft robots with dimensional analysis. It can be found that a larger elastic mismatch between the film and the substrate will lead to a larger driving force for interfacial delamination. The failsafe maps are also obtained based on the proposed calculation method, through which it can be observed very intuitively whether the structure with various material parameters has a tendency of interfacial delamination at different water depths.