Contact fatigue damage analysis of shot peened gears by means of X-ray measurements

X-ray diffraction (XRD) is an experimental technique that can be used to measure the residual stress state in metals. The primary information that it is possible to get from such measures are the angle of maximum intensity of the diffracted X-ray beam and the width of the peak. These quantities are related to the residual stresses and to the distortion of the crystal grains. In this paper shot peened gears subjected to rolling contact fatigue tests under operative conditions are considered. XRD measures performed before and after the tests allowed to evidence the evolution of the residual stress state and of the grain distortion due to damage development.