Date of Award
Doctor of Philosophy
Electrical and Computer Engineering
David C. Jiles
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 slopes of those, using a fitting algorithm.
Kypris, Orfeas, "Detection of sub-surface stresses in ferromagnetic materials using a new Barkhausen noise method" (2015). Graduate Theses and Dissertations. 14373.