Fast defect parameter estimation based on magnetic flux leakage measurements with GMR sensors

Issue title: OIPE 2010

Article type: Research Article

Authors: Reimund, Verena^{a; *} | Blome, Mark^a | Pelkner, Matthias^a | Kreutzbruck, Marc^a

Affiliations: [a] Department 8 Non-Destructive Testing, Federal Institute for Materials Research and Testing, BAM Berlin, Unter den Eichen 87, 2205, Berlin, Germany

Correspondence: [*] Corresponding author: Verena Reimund, Federal Institute for Materials Research and Testing. E-mail: verena.reimund@bam.de

Abstract: We present a fast inverse scheme that is capable of simultaneously estimating the parameters depth, opening and length for rectangular 3D geometries of surface-breaking defects. The parameter estimation is realized by an iterative least-squares minimization using the trust-region reflective algorithm. A semi-analytic magnetic dipole model that allows the sensor characteristics to be incorporated is used for predicting the stray magnetic fields. Giant magneto-resistance (GMR) measurements were carried out on a test specimen that includes a series of artificial defects. For the estimation of the defect depths relative errors between 0.6% and 15.9% have been obtained. Due to its very low computational costs, the inverse scheme can suitably be employed in automated production environments.

Keywords: Magnetic flux leakage, GMR sensor, nonlinear least-squares optimization

DOI: 10.3233/JAE-2011-1391

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 37, no. 2-3, pp. 199-205, 2011