success with fairly simple and obvious patterns such as tensile structures and the computation of shapes to 5 remove stress concentrations. The Eiffel Tower, for example, has demonstrated the advantages of structural hierarchy largely ignored by engineers,6 yielding a life six times longer than its designed 20 years. The hierarchical structure of its struts results in significantly greater resistance to catastrophic failure; the hierarchical arrangement of holes in wood gives control over fracture.7 This could easily be imitated in structural concrete by controlling the sizes and distribution of voids in the structure, except that we have no idea of the optimum ratio of void-to-material or of the ratio of size of small-to-large voids. In hardwoods this ratio is probably 1:10. The interfaces between different size levels within a hierarchy allow the levels to be decoupled; for instance, stiffness (arising from interatomic bonds: nanometre interactions) can be separated from fracture (arising from starter cracks: micrometre to millimetre interactions).8 The third level of translation is more closely integrated with current practice in engineering and design. It is founded on the TRIZ system (a name derived from the Russian acronym of ‘Theory of Inventive Problem Solving’), which was developed specifically for solving engineering problems. The patterns are more abstract, but are there, in that problems are defined and solved within a closely defined framework based on a large number (probably more than 3 million) of published patents. The method of interrogation is to ask not just ‘What did I have to change?’, as at the second level, but ‘What did I want to improve and what was stopping me making that improvement?’ This is a very well-established construct that can be traced to Heraclitus in ancient Greece, but is easily recognised in the dialectic motion between thesis and antithesis based on Hegelian philosophy (taught routinely in Russian schools) that leads to synthesis – the solution to the problem. This is probably the most powerful pattern, and TRIZ formulates it so that it is almost impossible not to achieve a novel solution. The novelty is based in the ability of TRIZ to ignore the walls that most people erect between their areas of expertise or knowledge, enabling access to ‘unknown knowns’ – things you didn’t know you knew – which are not recognised because they seem irrelevant to the problem. The three main rules to follow are: 1) to imagine the ideal result irrespective of the technology required to deliver it; 2) to state that result in terms of the function required rather than the means of delivery; 3) to list and be aware of all of the available resources (including time, gravity, space and so on).
TRIZ has other tricks, too, some of which show that technology evolves in a way similar to evolution. For instance, objects become more complex and compartmentalised in ways that not only parallel organic evolution, but can be used to predict technical developments. These evolutionary trends of technology have been used to write patents for machines and structures that have yet to be invented.
Biomorphic design might take on a new significance if, instead of ignorantly copying the shapes of animals and plants, we were to acknowledge that biomimetics teaches that shape is the most important parameter of all. Even so, the ways in which biology and technology solve problems can be very different. Using analysis at levels two and three we have developed some simple design tools. These have been used by Salmaan Craig at Buro Happold to design a form of insulation that will allow the re-radiation of heat to the night sky and control the temperature of a building without recourse to an air conditioner or any other machine.9 The secret is to introduce orientated tubes into the insulation so that the long-wave radiation of heat can pass straight through them. Biomorphic design might take on a new significance if, instead of ignorantly copying the shapes of animals and plants, we were to acknowledge that biomimetics teaches that shape is the most important parameter of all. 4 Notes 1. Hugh Aldersey-Williams, Zoomorphic: New Animal Architecture, Laurence King (London), 2003. 2. Julian FV Vincent, Olga A Bogatyreva, Nikolay R Bogatyrev, Adrian Bowyer and AnjaKarina Pahl, ‘Biomimetics – its practice and theory’, Journal of the Royal Society Interface 3, 2006, pp 471–82. 3. Julian FV Vincent and Paul Owers, ‘Mechanical design of hedgehog spines and porcupine quills’, Journal of Zoology 210, 1986, pp 55–75. 4. Ulrike GK Wegst, ‘The mechanical performance of natural materials’, PhD thesis, University of Cambridge, 1996, pp 1–128. 5. Claus Mattheck, Design in Nature – Learning from Trees, Springer (Heidelberg), 1998. 6. Rodney S Lakes, ‘Materials with structural hierarchy’, Nature 361, 1993, pp 511–15. 7. David G Hepworth, Julian FV Vincent, Graham Stringer and George Jeronimidis, ‘Variations in the morphology of wood structure can explain why hardwood species of similar density have very different resistances to impact and compressive loading’, Philosophical Transactions of the Royal Society A 360, 2002, pp 255–72. 8. Julian FV Vincent, ‘Biomimetic materials’, Journal of Materials Research 23, 2008, pp 3140–7. 9. Salmaan Craig, David Harrison, Anne Cripps and David Knott, ‘Biotriz suggests radiative cooling of buildings can be done passively by changing the structure of roof insulation to let longwave infrared pass’, Journal of Bionic Engineering 5, 2008, pp 55–66. Text © 2009 John Wiley & Sons Ltd. Images: pp 74-5 © Darryl Torckler/Getty Images; pp 76, 78 © Julian Vincent; p 77 © Russell Kightley/Science Photo Library; p 79 © Salmaan Craig; p 80 © Georgette Douwma/Science Photo Library
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