Degradation Mechanism of the Golf Balls in High Temperature and High Humidity Environment and Development of Its Evaluation Technique

Abstract

　　　In order to detect degradation in golf balls, degradation mechanism in golf ball was investigated and ultrasonic testing technique was applied to evaluate degradation in golf balls. Degradation mechanism of golf ball was first studied during water, high temperature and high temperature with high humidity environment. Degradation was evaluated by using restitution test, indentation test and compression test. Coefficient of restitution and hardness were rapidly changed in high temperature with high humidity environment, respectively. Hardness of the cover increased with increasing test time and hardness of core decreased with increasing test time. There was good relationship between change in hardness of cover and compression stiffness that detected in compression test in the balls used in this study. Ultrasonic testing was next applied. Change in arrival time of symmetrical mode wave that was propagated in the cover was corresponded to the change of hardness in the cover. Thus, degradation of the golf ball was roughly estimated by using ultrasonic technique in this case.