1989 Volume 38 Issue 430 Pages 847-853
The X-ray stress analysis at an arbitrary stress level during cyclic loading is effective to make clear the effect of residual stress on fatigue behavior. The method of sampling the diffracted X-rays at only one applied stress level in a short time during cyclic loading is required to perform such X-ray stress measurement, because the actual stress of specimen always changes during stress measurement.
This paper suggests the method of measuring the diffraction profile during cyclic loading by using an X-ray stress analyzer with a position sensitive proportional counter (PSPC) and discusses the accuracy of this X-ray stress measurement.
The results obtained are summarized as follows:
1) The method of time-resolved measurement of the diffraction profile by using PSPC was established. X-rays are constantly irradiated on the specimen during cyclic loading, and as soon as the applied stress reaches to a set stress level, the diffracted X-rays are sampled for a minute time, and the profile is determined by integrating the diffracted X-rays for several time-resolved samplings at this applied stress level.
2) The X-ray stresses at various levels of applied stress were measured very accurately. However, when the sampling time per one cycle was very short, the error of the X-ray stress increased.
3) The number of cycles needed for the stress measurement was considerably decreased by using a stress analyzer with PSPC. It was also decreased by decreasing the preset peak counts for measuring diffraction profile as well as the angles of X-ray incidence for the analysis.
4) It was confirmed by the time-resolved X-ray stress measurement that the actual stress during cyclic loading was the algebraic sum of the applied stress and the residual stress.
