Residual Stress Changes in Fatigue. Volume 2. A Simulation Model for Stress Measurements in Notched Test Specimens by X-ray Diffraction

摘要

The state of stress developed during fatigue testing of notched specimens was modeled analytically. From this model, the X-ray response to the stress state of the specimen was determined with an aim of measuring the X-ray effects that result from residual stresses. This model was also used to estimate the error in stress measurements caused by a stress gradient. The error in the measured stresses caused by the varying radius of curvature of the test specimen was also studied. It was concluded that the stress distribution model for an infinite specimen can be extended to a specimen of finite geometry with an error of approximately 3 percent; that precision in positioning the X-ray beam on the specimen is very important; and that residual stress measurements are feasible along the edge of the specimen. Keywords: Aluminum; Aluminum alloys; Stress mechanics; Airframes; Fatigue (Mechanics); Fatigue life; Predictions; Failure (Mechanics); Spectra; Computerized simulation; Residual stress; X-ray diffraction. (kt)