Sports Engineering: Material World
New Scientist: Instant Expert 24
July 7, 2012
Sports equipment designers have to work out what materials might be best for a bicycle frame or a tennis racket. With such a vast range of materials available, where do they start? One valuable tool is a materials selection chart. Routinely used by engineers, these charts show combinations of properties plotted against each other, such as density versus stiffness. The result is a “material space” populated with blobs, each describing a class of materials, such as wood, polymers and metals.
In 1995 Ulrike Wegst and Michael Ashby, both then at the University of Cambridge, published the first paper showing how selection charts could be used to identify which materials would work best for sports.
With rowing, for instance, an oar must be able to withstand large forces during the stroke and yet must bend just the right amount to give the athlete the correct feel. An oar should also be as light as possible to minimise energy in accelerating its mass and also to keep the boat high in the water and to minimise drag. This points towards wood, glass fibre or carbon-fibre reinforced plastics.
Or consider the pole vault. The pole must be able to store large amounts of energy without breaking, while its mass is kept to the minimum. Bamboo comes out highly in the selection process, which explains why it was still in use in the 1950s. Today glass fibre and carbon fibre are the materials of choice because they are more flexible, store more energy and can be shaped to enhance performance further.