Eddy Current Technique Based on ${\rm HT}_{\rm c}$ -SQUID and GMR Sensors for Non-Destructive Evaluation of Fiber/Metal Laminates

In this work we present non-destructive evaluation measurements on fiber/metal laminate specimen by using eddy current techniques employing HT_c SQUID (superconductive quantum interference device) and giant magneto-resistive (GMR) sensors. Our aim is to compare the performance and the capability of HT_c SQUID and GMR sensors to detect the presence of damage inside FML composite materials. Experimental results concerning the detection of artificial defects in aeronautical structures with high magnetic sensitivity by using HT_c SQUID, and with high spatial resolution using GMR, will be presented and discussed.