Smart Sensor and Actuator Technologies for SHM

The design of smart structures depends on the appropriate use of smart materials. The commonly used smart materials can be classified into four major groups

• piezoeletric
• magnetostrictive
• phase-transition dependent
• electro-rheological fluids

Piezoeletric materials develop electric charge on application of mechanical stress (the direct effect) and get strained due to the application of an electric potential (the converse effect).

Magnetostrictive materials display similar direct and converse effect between mechanical and magnetic field. Shape memory alloys deform during a phase change from martensite to austenite state. This phase transition may be caused due to stress or temperature leading to volumetric changes in the material. The electro-rheological fluids are a class of specially formulated suspensions which undergo a change in viscosity in the presence of applied electric field and modify the rheological behavior of carrier fluid . The shape memory alloys and electro-rheological fluids are mainly used for actuation purposes such as vibration and noise control while the piezoelectric and magnetostrictive materials are used for both sensing and actuation.