Mechanical Interlocking of Biological Fasteners

Abstract

Microstructures responsible for temporary arresting of contacting surfaces are widely distributed on surfaces in different organisms. They have different density of outgrowths and surprisingly not ideal distribution patterns. This is why they are often called probabilistic fasteners. Their size, shape and the density of their outgrowths do not correspond exactly to each other and interact by generating strong resistance force against acting force without precise positioning of both surfaces. For example, this kind of attachment is of importance for functioning of some biomechanical systems in insects. One can suggest that different structure of the interlocking devices is optimized by natural selection to get appropriate mechanical arrest. In this chapter, we simulate such a system numerically, both in the frames of continuous and discrete dynamical models. The feathers of modern birds are waterproof, breathable, lightweight constructions combining thermo-isolation, rigidity and flexibility due to the feather’s ability to hold its parts together by a specific pattern of hooklets. The feather vane can be separated into two parts by pulling neighboring barbs apart, but original state can be re-established easily by lightly stroking through the feather. Hooklets responsible for holding vane barbs together are not damaged by multiple zipping and unzipping cycles. A model is developed which reproduces zipping and unzipping behavior in feathers similar to those observed in biomechanical experiments performed on real bird feathers.

6.1 Supplementary Electronic Material(s)

(MP4 2515 kb)

(MP4 2201 kb)

(MP4 2497 kb)

(MP4 11986 kb)

(MP4 3134 kb)