What are auxetic materials?

Auxetic materials are materials with a negative Poissonís Ratio, i.e. become fatter when stretched and thinner when squashed .
Figure 1: Loading in the Y-direction of a conventional and auxetic honeycomb structure

What are auxetic materials like?

Very few exist naturally but recently more have been fabricated by modifying the microstructure of existing materials e.g. foams, polymers. Structures for molecular auxetics have been proposed, which are expected to be intrinsically superior to the microstructural auxetics so far developed .

What advantages do auxetic materials offer?

Apart from the scientific value of having materials with a negative Poisson`s ration, auxetic materials show enhanced mechanical properties such as:

(c) J.N. Grima, March 2000