The application of microwaves for detecting surface cracks receives great attention recently. An electromagnetic model for finite surface crack detection is developed and its results are compared with some experimental results to verify its integrity. An open-ended waveguide sensor is used to scan a metal surface with a crack in it. The crack is then modeled as a small waveguide being fed by a larger one. The presence of the crack causes higher order modes to be generated which in turn influence the properties of the standing wave set up inside the waveguide. Strategic probing of the standing wave properties is used to indicate the presence of a crack. The distribution of the tangential electric field on a metal surface is investigated. This is done to check whether the boundary conditions have been properly forced. The behaviour of crack characteristic signals as a function of varying crack length and location within the sensor aperture is investigated by a numerical simulation. A finite fatigue crack is fully detected at 38 GHz to demonstrate the practical feasibility and potential of this technique.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 3, pages 1567 - 1572 Publisher:Ashgate Publishing Company
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