Extreme enhancement of interfacial adhesion by bulk patterning of sacrificial cuts

Many biological materials, such as bone and nacre, gain their strength and toughness through the formation of sacrificial bonds and hidden length structures. Here, inspired by these structural features, we propose a new mechanism for enhancing the interfacial adhesion toughness between an elastic body and a rigid substrate through patterning sacrificial secondary cuts in the bulk elastic material. The proposed sacrificial cuts are designed to break prior to detachment, altering the load path in the material and adding more compliance to the system, thus, increasing the total amount of work required before detachment while enabling independent control of the peak stress amplitude. Numerically, we use the finite element method to show that interfacial adhesion may be extremely enhanced by using multiple layers of sacrificial cuts and we provide a simple analytical framework to explain the underlying mechanism. Furthermore, we show that the overall behavior is tunable by changing the geometric and material parameters of the sacrificial cuts. In particular, the total work of adhesion may be made to increase linearly with the number of layers of the cuts. We discuss our findings in the context of enhancing interfacial adhesion by modulating the bulk geometric properties.