Systematic numerical investigation of the role of hierarchy in heterogeneous bio-inspired materials

It is well known that hierarchical structure is an important feature in biological materials to optimise various properties, including mechanical ones. It is however still unclear how these hierarchical architectures can improve material characteristics, for example strength. Also, the transposition of these structures from natural to artificial bioinspired materials remains to be perfected. In this paper, we introduce a numerical method to evaluate the strength of fibre-based heterogeneous biological materials and systematically investigate the role of hierarchy. Results show that hierarchy indeed plays an important role and that it is possible to “tune” the strength of bio-inspired materials in a wide range of values, in some cases improving the strength of non-hierarchical structures considerably

The "Egg of Columbus" for Making the World’s Toughest Fibres

In this letter we present the "Egg of Columbus" for making fibres with unprecedented toughness: a slider, in the simplest form just a knot, is introduced as frictional element to dissipate additional energy and thus demonstrating the existence of a previously "hidden" toughness. The proof of concept is experimentally realized making the world’s toughest fibre, increasing the toughness modulus of a commercial Endumax macroscopic fibre from 44 J/g up to 1070 J/g (and of a zylon microfiber from 20 J/g up to 1400 J/g). The ideal upperbound toughness is expected for graphene, with a theoretical value of 10^5 J/g. This new concept, able of maximizing (one fold increment) the structural robustness, could explain the mysterious abundance of knot formations, in spite of their incremental energy cost and topological difficulty, in biological evolved structures, such as DNA strands and proteins

A New Concept for Smart Drug Delivery: Adhesion Induced Nanovector Implosion§

In this paper we show that controlling adhesion in highly flexible nanovectors can help in smartly delivering the drug. The high flexibility of the nanovector is used to smartly deliver the drug only at the target site by the new concept of “adhesion induced nanovector implosion”; a liquid drop analogy is developed for the calculations