機械的特性の変化を用いた金属バットの疲労評価

抄録

Sports everywhere have been becoming popular in the world. High performance players really desire developing the performance to be a winner in their field. However, choosing of the equipment which matched player’s senses take much time, because the relations between human senses and equipments are unclear. Therefore, the relations between human senses and equipments are classified in this study. The evaluation method used that both human senses and the characteristic of the equipment are varied by fatigue of the equipment. The target of evaluation is a metal bat for baseball. The procedure of the experiment is as follows. Firstly, the characteristics of the bat to be measured are center of gravity, vibration, frequency of impacting sound, deflection. Secondly, a bat is fatigued by batting with a ball speed of 120 km/h. The deflection of the bat and frequency of vibration are measured every 100 hits. The vibration is measured with a strain gauge. The vibration measurement is necessary for how much damaged material of a bat is. As mentioned above, transition of the characteristics of the bat due to fatigue is investigated, while the batting and the measurement as mentioned above are respectively continued. Finally, we measure the all of characteristics assuming which is of the deteriorated bat and investigate characteristics of the bat related to human senses. As a result of the experiment, the variations of deflection, vibration and sound are observed when the bat fatigued. In the case of deflection, softening is observed, and in the case of vibration and sound. The occurrence of increase and decrease of vibration and sound pressured beating are observed. In conclusion, the deflection, the vibration and the hitting sound affect human senses.