Portable eddy current NDT instrument using two different implementations.
ABSTRACT This paper describes two implementations towards the development of a portable low-cost system capable of detecting defects on metallic surfaces through non-destructive testing. The defect detection is made via an eddy-current probe using a giant magnetoresistor (GMR) sensor. Both approaches use a computer mouse as a position device to locate the probe and deliver a graphical representation to facilitate the defect analysis. One implementation is based on a planar excitation coil, embedded power supplies and the signal processing is made by a dsPIC. The dsPIC controls the signal generation, the measurement procedure and the communication. The defect visualisation can be made in a LCD in real-time or transmitted to a PC. The other implementation uses a low-cost analog system to reduce the data processing required to detect the surface defects. The controller is a PIC microcontroller that does all the analog/digital conversions and transmits the defect data to a PC via wireless channel.
Full-textDOI: · Available from: Helena G. Ramos, Jun 09, 2015
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ABSTRACT: Eddy current sensors, as one of nondestructive testing and evaluation instruments, have been widely used in displacement measurement as well as defect characterization. However, in eddy current displacement measurement, the test not only depends on the displacement between the coil and samples, but also relates to the electrical and magnetic properties (such as electrical conductivity and magnetic permeability) of samples. So, the eddy current sensor is limited to test one sample after one calibration. In order to make eddy current sensors compatible with more samples after one calibration without testing error, this paper designed a new eddy current displacement instrument extended from the previous theoretical analysis and experiment study investigating the relationship of the coil resistance and inductance. A series of experiments indicate that the designed new eddy current displacement instrument can eliminate the influence of the samples' electromagnetic properties effectively.NDT & E International 06/2012; 48:16–22. DOI:10.1016/j.ndteint.2012.02.001 · 1.72 Impact Factor