University of Twente Student Theses


A finite difference time domain model of an eddy current based measurement system

Janssen, Oskar (2009) A finite difference time domain model of an eddy current based measurement system.

[img] PDF
Abstract:Industrial companies often use large steel tanks to store all kind of liquids. Due to stress and weather influences the tanks protecting coating can get damaged and corrosion can occur. Corrosion is an auto-catalytic chemical process that needs to be detected in an early stage to prevent leakage. A scanner has been developed to detect these corrosion pits by means of eddy currents. The scanner uses 2 active coils in bridge configuration to generate time-varying electromagnetic fields and measure responses. Magnets are used to magnetize the steel plate under investigation. Magnetization mitigates magnetic inhomogeneities and increases scanning depth. Based on the difference in complex impedance of the coils conclusions can be drawn about the condition of the steel. Although eddy current testing is a powerful method it appears to be hard to interpret signals of non-artificial defects. Therefore it is needed to gain more knowledge about eddy current responses. In this project a software model has been implemented using the finite difference time domain technique. This technique is especially developed for electromagnetic problems and calculated propagating waves in the time domain. Simulation results of artificial defects in unmagnetized steel show equivalent responses compared to measurements. A magnetization process has been implemented, but it has instability issues when using non-linearities. The model can be further improved by implementing properties of corrosion and optimizing calculations.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering MSc (60353)
Link to this item:
Export this item as:BibTeX
HTML Citation
Reference Manager


Repository Staff Only: item control page