Skip to main content Accessibility help
×
Home

Profile Fitting in Residual Stress Determination

  • T. J. Devine (a1) and J. B. Cohen (a1)

Extract

Of major importance in the determination of residual stress via diffraction is the accuracy of the measurement of the scattering angle (2 θp) of a Bragg peak. This determines the accuracy of the interplanar (d) spacing and hence the strain and stress. In the U.S., the most commonly accepted method of determining peak position is a parabolic fit near the top of a peak. (While a diffraction peak is not parabolic, this is a satisfactory function near the maximum.) The error in this procedure has been derived and tested, and it has been shown that a multipoint fit with a least 7 points is rapid and as precise or more precise than the centroid, the bisector of the half width, or cross correlation, except for sharp peaks in which case the centroid or cross correlation are slightly better. Thus a parabolic fit is generally useful and, since a least-squares fit to this function is readily carried out on modem micro-processors, automatical of a stress measurement is possible, including evaluation of errors.

Copyright

References

Hide All
1. Thomsen, J. and Yap, F.Y., Effect of Statistical Counting Error on Wavelength Criteria for X-ray Spectra, Res. MBS. 72A: 198(1968).
2. James, M.R. and Cohen, J. B., Study of the Precision of X-ray Stress Analysis, Adv. X-Ray Analysis. 20: 291 (1976).
3. Knuutila, M., “ConputerGontrolledResidual Stress Analysis and Its Application to Carburized Steel”, Dissertation No. 81, Department of Mechanical Eng., Linkoping Univ. Sweden (1982).
4. Wilson, A.J.C., Statistical Variance of Line Profile Parameters, Measures of Intensity, Location and Dispersion, Acta Crystallogr., 23: 888 (1967).
5. James, M.R. and Cohen, J.B., The Application of a Position-Sensitive Xray Detector to the Measurement of Residual Stresses, Adv. X-Ray Analysis. 19: 695 (1976).
6. James, M. and Cohen, J.B., “PARS” - A Fortable X-ray Analyzer for Residual Stresses, Testing and Evaluation, 6: 91 (1978).
7. Mignot, J. and Rcndot, D., Application du Lis sage des Raies de Diffraction des Rayons-X. la Separation du Doublet Kα1, Kα1, J. Appl. Crystallogr, 9: 460 (1976).
8. Hall, M.M., Veeraghavan, V.G., Rubin, H. and Winohell, P.G., The Approximation of Symmetric X-ray Peaks by Pearscn Type VII. istributions, J. Appl. Crystallogr., 10: 66 (1977)
9. Spendley, W., Hext, G.R. and Himsworth, F.B., Sequential Application of Simplex Designs in Optimization and Evolutionary Operation, Technciaetrics, 4: 441 (1962).
10. blelder, J.A. and Mead, R., A Simplex Method for Function Minimization, Ihe computer Jrnl., 7: 308 (1965).
11. Hamilton, W.C., “Statistics in Physical Science”, Ronald Press Co., New York (1964).
12. Devine, T.J., Comparison of Full Profile Peak Finding Methods For Use in X-ray Residual Stress Analysis, Thesis, M.S., Northwestern University (1985).

Profile Fitting in Residual Stress Determination

  • T. J. Devine (a1) and J. B. Cohen (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed