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Proceedings Paper

Finite-element analysis of a magnetic sensor to detect permeability changes due to residual stresses in ferromagnetic materials
Author(s): Madhav Rao Govindaraju; Gopichand Katragadda; John L. Wallace
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Paper Abstract

High strength steel alloys (such as 300 M) used in naval aircraft engine and landing gear components are subjected to cyclic loading in service and found to be highly susceptible to fatigue cracking. There is a critical need for nondestructive evaluation techniques which can detect both cracking and potential crack nucleation sites within these components. An innovative electromagnetic technology called the stress induced-magnetic-anisotropy (SMA) technique has been proposed to be used to detect and evaluate residual stresses. SMA measures residual stresses by sensing the changes in magnetic flux induced in directions parallel and perpendicular to the stress. A novel probe and instrumentation is being developed to simultaneously detect both subsurface residual stresses and stress-induced cracking in coated and uncoated ferromagnetic structures. Finite element analysis has been used to determine the distribution of magnetic flux density and inductance of the probe under varying AC fields. Using ANSYSTM EMAG, the effect of varying frequency of the excitation field, permeability and dimensions of the core have been analyzed. The paper describes how finite element analysis can be used in design and development of the probe and in understanding its behavior.

Paper Details

Date Published: 31 March 1998
PDF: 9 pages
Proc. SPIE 3396, Nondestructive Evaluation of Materials and Composites II, (31 March 1998); doi: 10.1117/12.301535
Show Author Affiliations
Madhav Rao Govindaraju, Karta Technology, Inc. (United States)
Gopichand Katragadda, Karta Technology, Inc. (United States)
John L. Wallace, Karta Technology, Inc. (United States)

Published in SPIE Proceedings Vol. 3396:
Nondestructive Evaluation of Materials and Composites II
Steven R. Doctor; Carol A. Nove; George Y. Baaklini, Editor(s)

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