A TMR based triaxial ECT probe

The paper proposes the improvement of an eddy current probe for non-destructive testing applied to the defect investigation on conductive materials. The goal is to increase the defects detection sensitivity regardless of the mutual orientation between the defect and the sensing axis of the probe while the test is performed. In particular, the paper describes the realization of a suitable triaxial magnetic field detection system based on three single axis TMR (Tunnel Magnetoresistance Effect) sensors assembled on an eddy current probe. A probe performance evaluation was carried out on two aluminium plates with surface and subsurface cracks of 8 mm considering different mutual orientations between the cracks and the probe direction.