A two-dimensional model for enhanced adhesion of film-terminated fibrillar interfaces by crack trapping

Abstract

Experiments on a recently developed bioinspired film-terminated fibrillar array show significantly enhanced adhesion compared to a flat unstructured control sample. Adhesion is enhanced because the interfacial crack is trapped close to fibril edges. Using a finite element method and approximate analysis, we study a two-dimensional version of the fibrillar structure to understand the behavior observed in experiments. Several experimental observations are explained by the model: (1) the work to separate a unit area of the interface (W+) is larger than the work of adhesion (Wad) of the flat control sample; (2) the work to heal a unit area of the interface (W−) is smaller than the work of adhesion of the flat control sample; (3) W+ increases with fibril spacing; (4) W+ decreases with film thickness; and (5) W+ decreases with fibril height.