By introducing a strong electrical field, certain fluids can change to a near solid state. They are called 'electrorheological fluids' (rheology is the study of the viscosity and flow capacity of fluids). They can be made intelligent by coupling them to sensor devices which detect sudden movement. They have the potential to replace a range of mechanical devices such as vehicle clutches, springs and damping devices to eliminate mechanical vibrations.
Another class of smart fluid is activated by being exposed to a magnetic field. Linked to sensors, they would be ideal for buildings in earthquake zones. Buildings would be constructed off concrete rafts which in turn would be supported by an array of magnetorheo-logical dampers. At the onset of vibrations these would instantly change from solid to fluid and soak up the movement of the earth. In Tokyo and Osaka several recent buildings already exploit vibration damping and variable stiffness devices to counteract seismic movement.
There is yet another dimension to the characteristics of smart materials - materials that learn, that get smarter as they get older. They have an inbuilt degree of intelligence and are capable of optimizing their performance in response to feedback information.
What we will see in the near future are smart structures equipped with an array of fibre optic 'nerves' that will indicate what a structure is 'feeling' at any given moment and give instant information of any impending catastrophic failure. If the end of the last century was characterized by the rise of high technology with ever more complex electronic wizardry packed into ever smaller spaces, the future, according to materials scientists, 'may hold an increasing simplicity, as materials replace machines'.7 We will learn to be adaptive rather than assertive. This surely is what environmental responsibility is all about.
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