Abstract
The tuning of natural frequency of club head (NFH) is one of the most important factor to control the restitution characteristics of golf ball. Previous study reported the high correlation of coefficient of restitution (COR) and NFH when NFH was higher than the natural frequency of golf ball (NFB). But, when NFH was equal to or lower then NFB, these correlation was decreased. In this study, coupled oscillation model was applied to clarify the factor determine COR. Results were obtained as follows. Energy loss due to viscosity and hysteresis of golf ball (EDB) was almost proportional to NFH. Residual vibration energy of golf ball (EVB) was also proportional to NFH, but the magnitude was much less than EDB. On the other hand, the magnitude of residual vibration energy of club head (EVH) was varied with the variation of mass and elasticity distribution in club heads. The magnitude of EVH was very small when NFH was higher than NFB. But, in some case, it showed very large magnitude when NFH was equal to or lower than NFB. So, it was suggested that the low correlation of COR and NFH was caused by the variation of EVH in lower NFH condition.
