Introduction to magnetostriction

Fundamental research and development in smart materials and structures have shown great potential for enhancing the functionality, serviceability and increased life span of civil and mechanical infrastructure systems.

Researchers from diverse disciplines have been drawn into vigorous efforts to develop smart and intelligent structures that can monitor their own conditions, detect impending failure, control damage and adapt to changing environments. The potential applications of such smart materials and systems are abundant ranging from design of smart aircraft skin embedded with smart sensors for detection of structural flaws to bridges with embedded sensing elements to detect violent vibrations to name a few. Smart structures are generally created through synthesis by combining sensing, processing and actuating elements integrated with conventional structural materials such as steel, concrete, or composites. Various types of smart patches e.g. PZT patches and PVDF films have been used extensively as smart sensors to sense and detect damage in composite structures. These smart sensors provide real time sensing by exploiting their functional properties. However, piezoelectric sensors need direct electrical connectivity which may cause problem in structural integrity, particularly for embedded sensors. Also, piezoelectric sensors have a limited active life due to discharging of the sensors. Magnetostrictive materials (MS) and sensors based on such materials are more advantageous in this regard. With the commercial availability of Terfenol-D in particulate form; it is now feasible to developed MS particulate sensors to detect damages such as delamination with minimum effect on structural integrity on real time basis.