GMR and eddy current sensor in use of stress measurement

The use of high sensitive magnetic sensors like magnetoresistive sensors al lows novel applications in non-destructive testing (NDT), i.e. monitoring t he conditions of reinforced concrete constructions. Using novel magnetoresi stive sensors, a stress measurement of prestressed steel bars in concrete i s realizable. The giant magnetoresistive sensor (GMR sensor) and the eddy c urrent sensor are introduced here for high sensitive stress measurement. Th e combination of the eddy current technique with the magnetoelastic stray f ield measurement basically improves the mechanical stress measurement. (C) 2001 Elsevier Science B.V. All rights reserved.