Application of the Method of Caustics to Rolling Contact Fatigue and Simulation of the Caustic Images.

Abstract

As a series of studies to clarity the mechanism of crack initiation and propagation in rolling contact fatigue, the experimental method of caustics has been applied to disk-to-disk rolling contact fatigue tests. The cusp-like and round type caustic images were generated from the rolling contact point and the crack tip, respectively. Although the shape and size of the cusp-like image depending on the magnitude of applied load was constant, that of the round image was markedly changed with the relative position between the crack and the rolling contact point. The experimental caustic images have been simulated using a computer program developed by combining the theory of caustics with the theory of boundary element method. By comparing experimental caustic images with simulated ones, it is shown that the round type caustic image obtained in rolling contact is strongly affected by shear deformation of the crack.