Shear induced adhesion: Contact mechanics of biological spatula-like attachment devices

Alexander Filippov (1) , Valentin Popov (2) , Stanislav N. Gorb (3)

1 National Academy of Science
2 Institut für Mechanik
3 Department of Functional Morphology and Biomechanics

Most biological hairy adhesive systems of insects, arachnids and reptiles, involved in locomotion, rely not on flat punches on their tips, but rather on spatulate structures. Several hypotheses have been previously proposed to explain the functional importance of this particular contact geometry: (1) enhancement of adaptability to the rough substrate; (2) contact formation by shear force rather than by normal load; (3) increase of total peeling line due to using an array of multiple spatulae; (4) contact breakage by peeling off. In the present paper, we used numerical approach to study dynamics of spatulate tips during contact formation on rough substrates. The model clearly demonstrates that the contact area increases under applied shear force, especially when spatulae are misaligned prior to the contact formation. Applied shear force has an optimum describing the situation when maximal contact is formed but no slip occurs. At such equilibrium maximal adhesion can be generated. This principle manifests the crucial role of spatulate terminal elements in biological fibrillar adhesion.

Mots clés: Attachment; Friction; Roughness; Thin plates; Biomechanics; Biomimetics

Domaines: Sciences du Vivant [q-bio]

Alexander Filippov, Valentin Popov, Stanislav N. Gorb. Shear induced adhesion: Contact mechanics of biological spatula-like attachment devices. Journal of Theoretical Biology, 2011, 276 (1), pp.126. ⟨10.1016/j.jtbi.2011.01.049⟩. ⟨hal-00682406⟩