Development of Stress Analyzer Using Whole Back Reflection Ring
Yuichi SHITABA, Tetsuro ISHIKAWA, Shin-ichi OHYA and Koichi AKITA
Abstract:The X-ray stress measurement based on sin2ƒÕ method has been widely adopted. This technique is not entirely efficient, because it is necessary to measure each diffraction profile one after other at five and more incident X-ray angles. On the other hand, stress measurement based on cosƒ¿ method was proposed using X-ray film as detector. In this method, the stresses are determined from Debye-ring obtained at a single X-ray incident angle with high efficiency. However, it has the problem in this accuracy on stress determination. In this study, a new stress analyzer with sixteen position sensitive proportional counters (PSPC) radially arranged for incidence X-ray was developed. We examined to determine the plane stress components by multi-regression analysis using sixteen diffraction angles on a Debye-ring. As a result, stress components of ƒÐx and ƒÑxy were measured with sufficient accuracy. However, a stress of ƒÐy had large dispersion, because of low strain sensitivity in the y direction. Moreover, it was clarified that ƒÐy had pseud-multicollinearity on multi-regression analysis. The accuracy of ƒÐy value itself could not be improved, though an analysis to eliminate an effect of pseud-multicollinearity was carried out. In this paper, we proposed the new method to determine the components using two Debye rings obtained by X-ray incidences in both x and y directions. We tried to measure the residual stress components in the butt welded joint using the method. As a result, it was confirmed that the stresses, ƒÐx and ƒÐy, were obtained in the sufficient accuracy, and that the shear stress, ƒÑxy, was arising near the bond in the welds. Key Words:PSPC, Debye-ring, Plane stress components, Multi-regression analysis, Pseud-multicollinearity, Butt welded joint