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|Title: ||Assessment of defects in ferromagnetic metals with eddy currents|
|Authors: ||Oaten, Susan Rosemary|
|Advisors: ||Blitz, J|
|Publication 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.|
|Sponsorship: ||This work was sponsored by British Gas Plc.|
|Appears in Collections:||Institute for the Environment Theses|
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