An Experimental Investigation of a Smart Laminated Composite Beam with a Magnetostrictive Patch for Health Monitoring Applications

This paper presents an experimental investigation of a smart laminated composite beam with embedded/surface-bonded magnetostrictive patches for health monitoring applications. The concept is based on the principle that the Open Circuit Voltage (OCV) developed across a sensor due to an induced magnetic field in an actuator, shows a change in its amplitude due to the presence of delaminations. Sensitivity studies are performed on 8-ply unidirectional laminated composite beam specimens by varying its size and location with respect to the smart patch. Both surface mounted and embedded single smart patch collocated sensor–actuator configuration and an embedded two-patch non-collocated configuration are considered in this study. A horseshoe-type coil arrangement placed exactly over the magnetostrictive patch is used to induce magnetic field in the specimen. The study shows that the presence of delamination considerably alters the OCV across the sensing coil over a wide range of actuating current frequencies. The Damage Induced Voltage (DIV), which is the difference between the OCV across a sensor before and after the delamination, indicates the presence of damage. This voltage is of the order of milli-volts, and hence demonstrating the effectiveness of magnetostrictive patch for delamination detection. The experimental results compare well with the 3-D finite element simulation. The study shows that the collocated sensor–actuator configuration is more suited for health monitoring application compared to non-collocated configuration.