SPEED-UP NDT BASED ON GMR ARRAY UNIFORM EDDY CURRENT PROBE |
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| O. Postolache, A. Lopes Ribeiro, H. Geirinhas Ramos |
- Abstract:
- The usage of eddy current probes including single magnetic field sensor represents a common solution for defect detection in conductive specimens but it is a time consuming procedure when large surface specimens are tested. In order to speed-up the nondestructive testing procedure, eddy current probes including a single excitation coil and an array of detection coils represent one of the solutions to reduce the NDT times but mainly detects the surface defects. Deep defects require different sensing elements such as GMRs. In this work an optimized uniform eddy current probe architecture including two planar excitation coils, a rectangular magnetic field biasing coil and a GMR magnetometer sensor array is presented. An ac current is applied to the planar spiral rectangular coil of the probe, while a set of GMR magnetometer sensors detects the induced magnetic field in the specimens under test. The rectangular coil provides the dc uniform magnetic field assuring appropriate biasing of the GMR magnetometers of the probe, setting-up the functioning point on the linear region and at the same branch of GMR static characteristics. The differences of the images obtained on the same specimen surface for each GMR are reduced if all sensors are biased on the same working point. Elements of automated measurement system for NDT, including a validation procedure based on a 2D template matching algorithm and the corresponding experimental results are included in the paper.
- Keywords:
- non-destructive testing, uniform eddy current probe, giant magneto-resistance sensors array, sensor biasing, 2D template matching
- Download:
- IMEKO-WC-2012-TC4-O14.pdf
- DOI:
- -
- Event details
- Event name:
- XX IMEKO World Congress
- Title:
Metrology for Green Growth
- Place:
- Busan, REPUBLIC of KOREA
- Time:
- 09 September 2012 - 12 September 2012