Biomimetic wall-shaped hierarchical micro-structure: numerical simulation of sliding inception.

A finite element model is developed to study the behaviour of adhesion-governed contact of soft elastic wall-shaped projections and a rigid flat under normal and tangential loading. Bi-linear cohesive zone material is implemented to model the adhesive interaction of the contact, and Tresca's law of friction is used to model the tangential response. An assessment of maximum tangential load capacity of attachment devices based on dry adhesive contact is performed using the described model and the effects of geometrical properties are investigated. The value of maximum shear stress in the contact of PVS and a silicon flat is identified. The model reveals that the tangential load capacity of the wall-shaped projection is independent of normal load, and that increasing the length of the adhesive flap, as well as decreasing its thickness provides better tangential load capacity.