Negative Poissonís Ratio Materials (NPR) , also known as auxetic materials, anti-rubber, and dilational materials, are materials whose lateral width increases when stretched from either end. This behavior is counter intuitive, since most materials exhibit a Positive Poissonís Ratio (when stretched from either end, their lateral width decreases). The goal of this website is to help you understand how this material fundamentally 'works', and to document some new techniques to manufacture it.
Below is an extremely enlightening video from Bolton University, UK.
Do It Yourself: NPR BowTie
You can make a simple, quick prototype of the NPR (Negative Poisson Ratio) BowTie in the Bolton video with just a sheet of paper and a pair of scissors!
A Bit More Depth
The sequence of buttons on the menu above explains the detailed process followed here to discover some of the the issues involved in making NPR materials at finer scale, with different geometries and different materials.
The final product is shown below.