X-Ray Stress Measurement by The Cos α Method Using Two-Dimensional Detector Part 2: Measurement Procedure and Applications

Abstract

The cos α method utilizes the whole Debye-Scherrer ring recorded on a two-dimensional detector taken by single exposure of X-rays to determine the normal and shear stresses. The simple optical system of the cos α method makes stress analyzers smaller, lighter, and handier to use for on-site measurements. Part 2 of this review describes several precautions of the measurement procedure to acquire accurate stress values in short time. The accuracy of the stress measurement of the cos α method has been confirmed to be equivalent to that of the sin²ψ method for various metals. The shear stress as well as normal stress is determined by single exposure. Various advantages of the cos α method are clarified in the experimental procedure of stress determination. Spotty Debye-Scherrer rings obtained from coarse-grained metals sometimes hamper accurate stress determination. To overcome such difficulty, several possible techniques including the oscillations of beam and specimen are proposed, together with new analysis method for stress determination specific to coarse-grained materials.　Applications of the cos α method to welded members are presented, together with the future perspective of the method.