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Theses/Dissertations

Electrical Engineering

2015

Engineering Science and Materials

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Detection Of Sub-Surface Stresses In Ferromagnetic Materials Using A New Barkhausen Noise Method, Orfeas Kypris Jan 2015

Detection Of Sub-Surface Stresses In Ferromagnetic Materials Using A New Barkhausen Noise Method, Orfeas Kypris

Graduate Theses and Dissertations

In this work, a new, non-destructive method for obtaining stress-depth gradients in ferromagnetic structures was developed, using the information contained within magnetic Barkhausen emissions. A depth- and stress-dependent model for the frequency spectrum of Barkhausen emissions was derived and fitted to measured data obtained from steel samples with controlled stress-depth gradients. To achieve this, a library of signal processing and optimization algorithms was developed, which allowed the analysis of large datasets. To validate experimental procedures, a number of solid mechanics finite element simulations were carried out. Proof of concept is demonstrated by assuming linear stress-depth gradients and successfully calculating the ...