Propagation of peeling in finite adhesive pads

Adhesive pads are commonly used in both natural and engineering systems. A recent study [Cohen et al. Soft Matter 2018] has shown that the failure of finite pads, subjected to loading parallel to the substrate, can be triggered by different mechanisms; interfacial fracture that initiates near the pulling end, or curling that is triggered at the far end. The former mechanism was shown to be initially stable, while the later mechanism leads to unstable peeling. Although the initiation of peeling is now well understood, to determine the force bearing capacity of finite adhesive pads, the entire peeling process must be considered. In the present study, we thus analyze the evolution of detachment up to complete failure by combination of high precision experimentation, and numerical simulation. We find that regardless of the properties of the pad eventually all pads fail by curling while the interfacial cavity serves to delay the failure. Additionally, re-adhering of the cavitated region before onset of curling is observed. Additional work needs to be done to be able to capture the phenomenon numerically.