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Standard Deviations in X-Ray Stress and Elastic Constants Due to Counting Statistics

Published online by Cambridge University Press:  06 March 2019

Masanori Kurita
Masanori Kurita*
Affiliation:
Nagaoka University of Technology, Nagaoka, 940-21Japan
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Abstract

X-ray diffraction can be used to nondestructively measure residual stress of polycrystalline materials. In x-ray stress measurement, it is important to determine a stress constant experimentally in order to measure the stress accurately. However, every value measured by x-ray diffraction has statistical errors arising from counting statistics. The equations for calculating the standard deviations of the stress constant and elastic constants measured by x-rays are derived analytically in order to ascertain the reproducibility of the measured values. These standard deviations represent the size of the variability caused by counting statistics, and can be calculated from a single set of measurements by using these equations. These equations can apply Lu any meuhud for x-ray stress ifiesuremenL. The variances of the x-ray stress and elastic constants are expressed in terms of the linear combinations of the variances of the peak position. The confidence limits of these constants of a quenched and tempered steel specimen were determined by the Gaussian curve method. The 95% confidence limits of the stress constant were -314 ± 25 MFa/deg.

Type
VII. X-Ray Stress Analysis
Information
Advances in X-Ray Analysis , Volume 32: Thirty-Seventh Annual Conference on Applications of X-ray Analysis, August 1-5, 1988 , 1988 , pp. 377 - 388
Copyright
Copyright © International Centre for Diffraction Data 1988

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