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7/1/99 Daily Telegraph

Old Nature can still teach us a trick or two

Long ignored by the technocrats, biology is now proving to be rich in engineering solutions. Michael Fitzpatrick reports

IN the quest for design perfection, engineers and designers are turning to an expert who's been around for a few billion years - Nature. Mother knows best, after all, although scientists have been reluctant to admit it in the past.

" 'Biology has not quite got it right' was the prevalent thinking," says biologist Dr Julian Vincent, a co-director for the Centre for Biomimetics at Reading University, and champion of biomimicry. "Where nature might put curves, in a bone for example, an engineer would be happier reaching for his ruler and straightening it out."

Following centuries of distrusting nature and repeated attempts to master her, some scientists, technologists and engineers (with a little hi-tech cajoling) are now hoping she will reveal the secrets of what are seen as highly successful, low-energy-dependent designs. The result is the emerging science of Biomimetics, which, by using up-to-date analytical techniques, is helping put some of nature's better ideas to work in industry.

Engineers have been adept at synthesising a range of extremely useful materials. But they could do better. Kevlar, for example, is a remarkably strong fibre used in aeronautics and to make bullet-proof vests. It is made by applying considerable pressure to petroleum products heated to 1,400F.

To a spider the process would seem a trifle hyperactive. Without using anything like that kind of heat, spiders produce a material that's 10 times stronger than an equivalent-sized steel wire - and it's biodegradable.

Clearly, a synthetic equivalent of spider thread would be of enormous benefit. Biomimetics could help scientists create it, not by copying it exactly but by incorporating some of nature's design aspects.

Other muses proving particularly inspirational include subjects as diverse as sea cucumbers, mushrooms, hedgehog spines and even our own bones.

Working for the first time with biologists such as Vincent, engineers are finding the answers to technical and design problems that have eluded their slide rules in the past. The knowledge biologists have gleaned from mechanics in the natural world can be particularly helpful when struggling to find the optimum design, says Vincent. "We have the tools for analysing biological systems to a sufficiently deep level. And the tools and material science for recreating some of those ideas at a sufficiently deep level so that the transfer of technology is possible."

These latest methods include microscopy techniques, the theory of understanding materials, fracture mechanics, and composite theory.

All these are coming together, says Vincent, to make the application of biomimetics a practical reality.

Among those seeking enlightenment via the arts of biomimicry is the British defence industry, which has been looking for a better aircraft design for years.

Could Vincent find something in nature that might improve the performance of military jets? Consider the sea cucumber, suggested the professor.

Studies of this seabed-dwelling creature have revealed a skin which the animal can stiffen, soften and stiffen again. The same design would be useful in creating a reconfigurable airfoil using materials based on those in the skin of the sea cucumber, says Vincent.

"It's a matter of seeing how a sea cucumber does it with its organic matrix and adapting that for use by transferring those ideas to, say, using carbon fibre."

Engineers also have a lot to learn from wood (energy efficiency and load-bearing), shells (toughness), and antler bone (toughness, again - tougher than any man-made composite).

"What nature can teach us best," says Vincent, "is that we don't need terribly hi-tech materials but have to be more careful about the design. Cellular materials in particular are nature's forte."

Hedgehogs, for one, benefit from some subtle cellular engineering. The spiny hedgehog has the unique ability to drop from a relatively high place and bounce away safely on its quills. Hedgehogs' spines work so well because even though they show a coarser honeycomb structure than, say, the foam-like make-up of porcupine quills or plant stems, they are perfect for absorbing shocks. And, because of its weight-energy cost efficiency the hedgehog principle could be exploited for designing lightweight structures such as space stations, says Vincent.

More down-to-earth matters have engineers seeking a material that is tough but not brittle. Nature offers mother of pearl, or nacre, which is 500 to 3,000 times tougher than the chalk that constitutes 95 per cent of its bulk.

Bill Clegg, a professor of materials at Cambridge University, has made a close study of nacre: "I was looking at cheap ways of making toughened ceramics. The major problem is that they are difficult to make, and expensive. I found that the layered nature of nacre had excellent qualities of toughness and only bent under extreme pressure."

Using puff pastry technology, Clegg has developed a ceramic that has superior qualities of heat-resistance, toughness and, like its sea-shell equivalent, the ability to deflect cracks. Daimler, and Volvo Aerospace have helped to build Clegg's samples, which he says will be perfect for pouring molten steel. The development of jet-engine components has also benefited from Clegg's work in biomimetics.

But although the science of mimetics might be new, the use of nature-inspired designs is not. Earlier successes include the Crystal Palace and the Eiffel tower.

That Gustave Eiffel's wrought-iron structure resembles a huge, upturned peg-leg is no fluke. Inspired by the architecture of the human thighbone, its creator was originally fired by the work of Hermann von Meyer, a professor of anatomy at Zurich who unravelled the secrets of the way the femur efficiently carries off-centre loads. Mathematician and engineer Karl Cullman translated Von Meyer's findings into applicable theory and the mathematical model lead to the design of the Paris tower.

Designed for the Great Exhibition of 1851, Joseph Paxton's glass roof for his crystal palace was also a triumph of design by nature's example. A botanist by profession, Paxton grew the large water lily Victoria amazonica with leaves more than a metre across. He had noticed that the plant's intricate rib-like structure supported the great weight of each leaf. He borrowed the same principle for his palace.

Another plant, the prickly burdock, is probably one of the world's most successfully mimicked designs. With it forever getting caught in his dog's coat, it occurred to Belgian inventor Georges de Mestral that the same action would be a good way of joining two fabrics together. Velcro was the result.

In the coming "Age of Materials", engineers will be increasingly on the look-out to poach from biology, says Clegg.

"Some biologists find idea of biomimetics unacceptable, because in a lot of ways what we do is much cruder. We are not actually trying to copy faithfully, we were not trying to produce a shell, for example. What you see is something that has that property in the natural structure. Biomimetics is a fund of ideas."



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