The world has undergone two materials ages, the plastics age and the composite age, during the past centuries. In the midst of these two ages a new era has developed. This is the smart materials era. According to early definitions, smart materials are materials that respond to their environments in a timely manner. The definition of smart materials has been expanded to materials that receive, transmit or process a stimulus and respond by producing a useful effect that may include a signal that the materials are acting upon it.Smart materials cover a wide and developing range of technologies. A particular type of smart material, known as chromogenics, can be used for large areaglazing in buildings, automobiles, planes, and for certain types of electronic display. Smart materials have been around for many years and they have found a large number of applications. There are many types of the materials present some of them listed below: Shape memory alloy
2) Piezoelectric materials
3) Magnetostrictive materials
4) Magneto- and electro-rheological materials
5) Chromic materials
Due to the property of responding quickly with environment and many applications in daily life smart materials deserve a great future scope.
Smart materials have been around for many years and they have found a large number of applications. The use of the terms 'smart' and 'intelligent' to describe materials and systems came from the US and started in the 1980‟s despite the fact that some of these so-called smart materials had been around for decades. Many of the smart materials were developed by government agencies working on military and aerospace projects but in recent years their use has transferred into the civil sector for applications in the construction, transport, medical, leisure and domestic areas. The first problem encountered with these unusual materials is defining what the word” smart‟ actually means. One dictionary definition of smart describes something which is a stute or 'operating as if by human intelligence' and this is what smart materials are. A and back again when you return inside. This coating is made from a smart material which is described as being photochromic. There are many groups of smart materials, each exhibiting particular properties which can be harnessed in a variety of high-tech and everyday applications. These include shape memory smart material is one which reacts to its environment aby itself. The change is inherent to the material and not a result of some change in volume, a change in colour or a change in viscosity and this may occur in response to a change in temperature, stress, electrical current, or magnetic field. In many cases this reaction is reversible, a common example being the coating on spectacles which reacts to the level of UV light, turning your ordinary glasses into sunglasses when you go outside alloys, piezoelectric materials, magneto-rheological and electro-rheological materials, magnetostrictive materials and chromic materials which change their colour in reaction to various stimuli. The distinction between a smart material and a smartstructure should be emphasised. A smart structure incorporates some form of actuator and sensor (which may be made from smart materials) with control hardware and software to form a system which reacts to its environment. Such a structure might be an aircraft wing which continuously alters its profile during flight to give the optimum shape for the operating conditions at the time. II SHAPE MEMORY ALLOYS
Shape memory alloys (SMAs) are one of the most well known types of smart material and they have found extensive uses in the 70 years since their discovery
What are SMAs?
A shape memory transformation was first observed in 1932 in an alloy of gold and cadmium, and then later in brass in 1938.The shape memory effect...