Theoretical Limits in Detachment Strength for Axisymmetric Bi-Material Adhesives

Abstract Reversible dry adhesives rely on short-ranged intermolecular bonds, hence requiring a low elastic modulus to conform the surface roughness of adhered material. Under external loads, however, soft accumulate strain energy, which release drives propagation interfacial flaws prompting detachment. The trade-off between required compliance, for conformity, and desire reduced energy rate, better strength, can be achieved with bi-material adhesive having tip rigid backing (RB). This design strategy is widely observed in nature across multiple species. However, detachment mechanisms these are not completely understood quantitative analysis their strength still missing. Based linear fracture mechanics (LEFM), we analyze axisymmetric adhesives. We two main mechanisms, namely (i) center crack (ii) edge propagation. If sufficiently thin, mechanism dominates provides stable propagation, thereby toughening interface. ultimately provide maximum theoretical obtaining closed-form estimation an incompressible tip. In some cases, independent size, rendering interface flaw tolerant. finally compare our prediction experiments literature observe good agreement.