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Finite Element Modeling of the Bulk Magnitization of Railroad Wheels to Improve Test Conditions for Magnetoacoustic Residual Stress MeasurementsThe magnetoacoustic measurement technique has been used successfully for residual stress measurements in laboratory samples. However, when used to field test samples with complex geometries, such as railroad wheels, the sensitivity of the method declines dramatically. It has been suggested that the decrease in performance may be due, in part, to an insufficient or nonuniform magnetic induction in the test sample. The purpose of this paper is to optimize the test conditions by using finite element modeling to predict the distribution of the induced bulk magnetization of railroad wheels. The results suggest that it is possible to obtain a sufficiently large and uniform bulk magnetization by altering the shape of the electromagnet used in the tests. Consequently, problems associated with bulk magnetization can be overcome, and should not prohibit the magnetoacoustic technique from being used to make residual stress measurements in railroad wheels. We begin by giving a brief overview of the magnetoacoustic technique as it applies to residual stress measurements of railroad wheels. We then define the finite element model used to predict the behavior of the current test configuration along with the nonlinear constitutive relations which we obtained experimentally through measurements on materials typically used to construct both railroad wheels and electromagnets. Finally, we show that by modifying the pole of the electromagnet it is possible to obtain a significantly more uniform bulk magnetization in the region of interest.
Document ID
20040182343
Acquisition Source
Langley Research Center
Document Type
Other
Authors
Fulton, J. P. (Analytical Services and Materials, Inc. Hampton, VA, United States)
Wincheski, B. (Analytical Services and Materials, Inc. Hampton, VA, United States)
Namkung, M. (NASA Langley Research Center Hampton, VA, United States)
Utrata, D. (Association of American Railroads Chicago, IL, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 1992
Subject Category
Numerical Analysis
Distribution Limits
Public
Copyright
Public Use Permitted.

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