In this study, the spalling issue in ball-type Constant Velocity Joints (CVJ) was investigated. As one of the most common types of outboard CVJ, a ball-type CVJ has spalling problems caused by fatigue at the internal contact points. It causes noise and vibration in vehicles, which results in CVJ failures. This study provides a spalling-estimation model for a ball-type CVJ, which was developed by the following five steps. First, the relative coordinates of the internal contact points between each component were established by forward kinematics. Second, the acting forces were calculated according to the results of the relative coordinate analyses and the vehicle driving conditions, and then normal pressure at the contact points was derived by Hertz contact theory. Third, the maximum sliding speeds at the contact points were also calculated using slip motion analyses. These normal pressure and maximum sliding speeds were used to estimate the shear stresses at the contact points. Fourth, experiment to evaluate spalling occurrence was carried out under several contact conditions. Lastly, a spalling estimation model was developed based on the reliability analysis with experiment data. The developed model was verified by testing a ball-type CVJ under actual driving condition. The verified spalling estimation model accurately predicts the spalling occurrences in various driving conditions.
