In material science, toughness is a measure of the amount of energy a material can absorb before breaking. Kevlar, for example, can absorb some 80 Joules per gram before breaking but this is dwarfed by certain natural materials which are much tougher. The silk produced by the giant riverine orb spider, for instance, can absorb around 390 Joules per gram before breaking.
So there is great interest in finding new materials that can match or beat the performance of natural materials for applications that require high levels of energy absorption.
Today, Nicola Pugno at the University of Trento in Italy reveals a remarkably simple trick that dramatically increases the toughness of almost any kind of fibre. Indeed, Pugno says he has used the technique to create the world’s toughest fibre.
The new idea is deceptively simple–it involves no more than tying a slip knot in the fibre, creating a loop of extra fibre that can passes through the knot as it comes under tension.
mechanism is straightforward. When the fibre is placed in tension, the
slip knot begins to tighten and the extra material passes through the
knot, dissipating energy through friction.