Fracture of multilayer soft materials

In recent decades, soft materials such as hydrogels and elastomers have been rising and continuing to develop in engineering fields. Among them, layered stretchable structures composed of multilayer soft materials have attracted widespread attention due to their excellent mechanical properties and versatility. Notably, despite the rapid advancements in the design and functional development, there remains a scarcity of research on the fracture behavior of these multilayer soft materials. To address this largely unexplored issue, in this paper we study the fracture mechanics of multilayer soft materials. A theoretical framework is established to analyze the fracture modes of film-substrate structures composed of multiple layers of soft materials under tension. Then the proposed framework is applied to investigate the fracture of typical three-layered and four-layered soft structures with pre-crack in the films. The normalized driving force and critical stretches for different configurations of cracks are calculated. Furthermore, the failure phase diagrams for different film thickness are plotted. This work provides a theoretical basis for predicting the fracture of multilayer soft materials, thereby offering quantitative guidance for the design of soft layered structures with better fracture resistance.