Characterization of Surface Cracks Through The Local Magnetic Field Induced by Eddy Currents

It is important to reliably characterize cracks in metallic mechanical parts in order to assess the serenity of damage due to fatigue. The most important parameter for this is the crack depth. This is notoriously difficult with standard Eddy current techniques. We show here that this can be achieved by measuring the local magnetic field induced by Eddy currents flowing around the crack. This is done by using a high-density array of micro-Hall sensors integrated in a single CMOS chip with a spatial resolution of 10 mu m. We present the dependence of the signal on varying crack depths, liftoff and yaw angle. Finally, we study the response of the sensor to cracks in a DC magnetic field, i.e. the flux leakage due to the presence of a crack. This is especially relevant to cases where cracks appear predominantly close to edges with complex geometries for which it is difficult to induce clean Eddy currents.


Editor(s):
Rebello, Jma
Kojima, F
Chady, T
Published in:
Electromagnetic Nondestructive Evaluation (Xvi), 38, 227-237
Presented at:
17th International Workshop on Electromagnetic Nondestructive Evaluation, 17th International Workshop on Electromagnetic Nondestructive Evaluation
Year:
2014
Publisher:
Amsterdam, Ios Press
ISSN:
1383-7281
ISBN:
978-1-61499-353-7
Keywords:
Laboratories:




 Record created 2014-04-14, last modified 2018-01-28


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