Can a fibrillar interface be stronger and tougher than a non-fibrillar one?

Elasticity analysis and finite element simulations are carried out to study the strength of an elastic fibrillar interface. The fibrils are assumed to be in perfect contact with a rigid substrate. The adhesive interaction between the fibrils and the substrate is modelled by the Dugdale-Barenblatt model (DB). The condition for a fibrillar interface to be stronger than a non-fibrillar one is obtained for two regimes: (i) small fibril or flaw insensitive regime; (ii) large fibril or flaw sensitive regime. The transition between the two regimes is characterized by a dimensionless parameter that incorporates the material constants of the elastic fibrils and interfacial properties. The condition for a fibrillar interface to be tougher is also given. Lateral collapse is found to be detrimental to the strength and toughness of a fibrillar interface.