Flexible engineering
A recent article in Science 1 describes the creation of responsive materials, able to sense the environment and self-repair in the case of impending damage. This is an important notion for engineering, based currently largely on prescriptive designs and risk management by factors of safety. From nuclear power plants to solar cells and from toy cars to aircrafts, engineering design philosophy has been forecasting adverse future effects and counteracting them many times over, i.e. by applying large factors of safety. This has been a thoroughly inelegant approach, leading to inefficient designs in most cases and catastrophic failures during events that are not forecasted at design time.
The recent failure of the nuclear power plant infrastructure in Japan is a good example. The failure was not due to any component in the plant not being designed according to code – most had factors of safety many orders of magnitude than needed. It was due to a lack of flexibility – back-up systems requiring common inputs and showing similar design characteristics. The basic idea of forecasting events and counteracting them, always lead to designs that likely fail under events not forecasted or when combination of events happen in a sequence that is not forecasted. Prescriptive engineering has been with us for so long that both the education systems and practicing engineers find it extremely difficult to shed the status-quo principles.
One attribute that will help revolutionize engineering design and make it relevant for the present is a new generation of materials that behave differently. If the function of the material is not to defend forecasted events but rather adapt to the environment in the case of future (and not forecasted) events, then flexibility (not prescription) will become the fundamental tenant in design. The basic principle of engineering design should not be assuring that failure does not occur in forecasted events but rather allowing sufficient flexibility to limit catastrophic failure by the presence of redundant and uncorrelated systems and materials. Such a design, albeit being more redundant, will be substantially cheaper and lighter, as each component will be designed not to avoid failure but to adapt to uncertain adverse situations in an uncorrelated fashion.
The slumbering material scientists have left the design engineers holding tools from the last century. It is a mutual responsibility – they have to both wake up and smell the future.
1. Potential Solutions for Creating Responsive Materials, Karl Sieradzki
2. Flexibility : Flexible Companies for the Uncertain World http://www.crcpress.com/product/isbn/9781439816325
