In this course, three different techniques for health monitoring and damage detection of composite structures have been considered. Initially, piezoelectric sensors and actuators like PVDF films bonded to composite laminate are considered for active vibration control and damage detection. Later, magnetostrictive (MS) material like Terfenol-D in particulate form embedded in one of the layers of composite laminate is considered for damage detection. Lastly, experimental modal analysis of composite laminate is carried out on Laser Doppler Scanning Vibrometer to record vibration signatures of the structure which is used in non-contact sensing of structural damages.
Piezoelectric 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 charge from matersite to austenite states. 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 charge 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 sensors and actuation.
|
