Structures built with honeycomb cardboard are delivering ground-breaking results.
Engineering a cardboard surfboard
Cardboard sounds like an unlikely material for building surfboards but Dr Arnaud Marmier is attempting to convince you that this humble and very widespread material is capable of extraordinary things.
Unsurprisingly it has not been an entirely successful project though, as Arnaud explained: “I have surfed using these surfboards. Not all of them have leaked – one has survived!
“The cardboard core is good, but there are still problems with replacing the fibreglass skin. Polyurethane (PU) roof paint is a very promising alternative though.”
Building water vessels out of paper is not a new concept. In 1867 a box baron and his son built paper canoes and racing shells, which achieved sporting successes, until their factory burnt.
Recently, there has been a resurgence of interest in developing unlikely objects out of paper and cardboard.
Inspired by the early cardboard surfboards of Mike Sheldrake and projects around the world which have built bikes and bicycle helmets and even cathedrals out of cardboard, Arnaud became interested in what else can be built from a box.
During this project Arnaud found out a lot more about the engineering potential of cardboard.
It is something that you see every day - he commented that although ‘everything comes in a box’ the structure of cardboard is a lot more complicated than it looks.
Arnaud explained: “Corrugated cardboard is what’s known in engineering as a sandwich panel, a lightweight structure with two stiff skins backing a thick core.
“The core - the wavy structure in the middle, known as the flute - has a privileged direction, but so has the paper, as the cellulose fibres are aligned. In other words, corrugated cardboard is excellent in some directions, and poor in others.”
This design means that the material can be manipulated and engineered quite beautifully whilst remaining rigid, as long as the directions are well controlled.
It is the cardboard constructions with a honeycomb structure (a bit like a 3D puzzle with cardboards ribs) that are delivering the most ground-breaking results.
The complexity is high with a sandwich panel composed of smaller sandwich panels, themselves made with paper whose properties depend on orientation.
In fact, the bike helmet developed by Anirudha Surabhi and produced by Kranium is already in sale.
Some of the tests on these designs are suggesting a 30 per cent improvement in safety – but would this convince you to give cardboard a go?
Arnaud thinks people should consider it: “If the performance is better, why not? It could improve people’s lives.”
The surfboards themselves are made by creating a complicated mathematical model that enables the cutting machine to cut the surfboard shapes out automatically.
Arnaud explained: “Computer models, similar to 3D printing are used to send instructions about the shapes that need to be cut out.
“This means we can construct difficult objects by building these shapes like a jigsaw”.
However, covering the boards in an eco-friendly way continues to be a challenge.
Arnaud said: “What other people had done was cover it in resin and glass fibre. We are doing something different though and need to find a more environmentally friendly way.”
He has spent a long time trying to cover it with different materials, other than traditional coverings and discovered that paper, pva glue and polyurethane paint make a surprisingly effective covering.
It’s not fully green, but it’s an improvement on glass fibre and is something that can be done without much skill.
Arnaud will be talking about how he engineered the cardboard surfboard as part of Exeter Student Guild’s Research Uncovered series.