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Sensors 2012, 12(9), 12169-12183;

Routes for GMR-Sensor Design in Non-Destructive Testing

BAM Federal Institute for Materials Research and Testing, Berlin 12200, Germany
Laboratory for Measurement Technology, Saarland University, Saarbrücken 66123, Germany
Author to whom correspondence should be addressed.
Received: 21 June 2012 / Revised: 30 July 2012 / Accepted: 28 August 2012 / Published: 5 September 2012
(This article belongs to the Section Physical Sensors)
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GMR sensors are widely used in many industrial segments such as information technology, automotive, automation and production, and safety applications. Each area requires an adaption of the sensor arrangement in terms of size adaption and alignment with respect to the field source involved. This paper deals with an analysis of geometric sensor parameters and the arrangement of GMR sensors providing a design roadmap for non-destructive testing (NDT) applications. For this purpose we use an analytical model simulating the magnetic flux leakage (MFL) distribution of surface breaking defects and investigate the flux leakage signal as a function of various sensor parameters. Our calculations show both the influence of sensor length and height and that when detecting the magnetic flux leakage of µm sized defects a gradiometer base line of 250 µm leads to a signal strength loss of less than 10% in comparison with a magnetometer response. To validate the simulation results we finally performed measurements with a GMR magnetometer sensor on a test plate with artificial µm-range cracks. The differences between simulation and measurement are below 6%. We report on the routes for a GMR gradiometer design as a basis for the fabrication of NDT-adapted sensor arrays. The results are also helpful for the use of GMR in other application when it comes to measure positions, lengths, angles or electrical currents. View Full-Text
Keywords: giant magneto resistance; non-destructive testing; magnetic flux leakage; sensor array giant magneto resistance; non-destructive testing; magnetic flux leakage; sensor array
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Pelkner, M.; Neubauer, A.; Reimund, V.; Kreutzbruck, M.; Schütze, A. Routes for GMR-Sensor Design in Non-Destructive Testing. Sensors 2012, 12, 12169-12183.

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