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http://bura.brunel.ac.uk/handle/2438/5310
Title: | Assessment of defects in ferromagnetic metals with eddy currents |
Authors: | Oaten, Susan Rosemary |
Advisors: | Blitz, J |
Issue Date: | 1989 |
Publisher: | Brunel University Institute for the Environment PhD Theses |
Abstract: | A study was made to identify and size surface breaking defects in ferromagnetic materials with eddy currents, whilst eliminating unwanted signals due to changes in magnetic permeability and probe lift-off. The former was overcome by the use of high frequencies and the latter by utilising the lift-off to characterise the defects. The lift- off or "touch" method was shown to be advantageous in that one could test steel objects having irregular surfaces, such as occurring with the presence of welds. In addition a theoretical investigation was undertaken to relate changes in the magnetic permeability, electrical conductivity and values of lift-off to the components of impedance of a detecting coil located above the plane surface of a ferromagnetic metal. The resultant theory was confirmed by experimental measurements. |
Description: | This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. |
URI: | http://bura.brunel.ac.uk/handle/2438/5310 |
Appears in Collections: | Institute for the Environment |
Files in This Item:
File | Description | Size | Format | |
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FulltextThesis.pdf | 6.7 MB | Adobe PDF | View/Open |
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