Volume 9, Issue 5 (September 1981)
A Statistical Analysis of X-ray Stress Measurement by the Gaussian Curve-Fitting Method
Simplified equations for calculating peak position and its standard deviation caused by counting statistics, which is a fundamental source of scatter in X-ray stress measurement, are derived for the Gaussian curve-fitting method. These equations when used with an inexpensive microcomputer will facilitate a precise and rapid residual stress determination. The time required for calculating the peak position and its standard deviation with such a microcomputer is only 0.9 s.
The residual stress in a hardened structural steel, Type JIS S45C, was measured. The standard deviation in the stress as measured by the Gaussian curve method was smaller than that by the parabola method, which until now has been the most widely used technique.
The variation in peak position in the Gaussian curve method with the various selections of data points used in the calculation is also smaller than that in the parabola method. Since the correction for background has little influence on the results, it can be omitted to reduce the measurement time.