2017 年 83 巻 846 号 p. 16-00436
The metal bats are more advantageous than the traditional wooden bats due to their specific properties such as improved strength, lower cost, and durability. The National Collegiate Athletic Association (NCAA) only allows the use of bats whose bat-ball coefficient of restitution (BBCOR) is ≤0.50. Since there is a possibility that the value of BBCOR will be standardized in Japan as well, building the design method has become extremely important for controlling the value of the BBCOR. In previous studies, the BBCOR has been shown to decrease with an increase in the hoop frequency of the bat and the impact velocity of the ball. In this study, the equation for predicting the BBCOR from the relationship between the BBCOR and the impact velocity or the hoop frequency has been investigated by using a power law. From the BBCOR prediction equation, for an impact velocity of 61 m/s (as regulated by the NCAA), the hoop frequency in which the BBCOR is ≤0.5 has been determined. Furthermore, the hoop frequency was calculated using a finite element method that mostly corroborated the experimental value. The BBCOR could then be estimated when the hoop frequency was substituted back into the BBCOR prediction equation. It was shown that designing a bat may be possible without resorting to physical experimentation.
