著者

志村 芽衣 宮澤 隆 矢内 利政

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.17049, (Released:2017-12-20)

参考文献数

9

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The purpose of this study was to determine the impact conditions that enable a batter to hit a pitched ball toward the opposite field. Three-dimensional finite element analysis was used to construct a model for the impact between a baseball and a wooden baseball bat, and a series of simulations were conducted with various bat angles and under-cut distances. The bat angle at ball impact was set in a horizontal range from -31 to 20° and a vertical range from 0 to 51° with a 3° interval. The under-cut distance was altered by changing the vertical angle of the line of impact in a range from 0 to 30° with a 5° interval. The velocity and angle of projection of the batted ball were determined for each simulated condition. The simulation model was validated by comparing the simulation outcome with the corresponding experimental data obtained from opposite-field hitting practice performed by collegiate baseball players. The results showed that when a batter intends to hit a ball toward a given horizontal angle in the opposite field with the highest speed, the batter should impact the ball with the bat facing about 60% of the horizontal angle toward which to launch the ball and with the line of impact angled upward at 5~10° from the horizontal plane. In addition, the horizontal angle of the batted ball and the velocity of the batted ball were found to change systematically when the vertical angle of the line of impact and the vertical bat angle were altered: For a given horizontal angle toward which to launch the batted ball, there was a trade-off relationship between the vertical angle of the line of impact and the vertical bat angle.

著者

志村 芽衣 宮澤 隆 矢内 利政

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.64, no.2, pp.487-500, 2019-12-16 (Released:2019-12-20)

参考文献数

16

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The purpose of this study was two-fold; to determine the optimum impact condition for maximizing flight distance toward the opposite field and to examine the influence of the bat angles at impact on the batted ball characteristics (speed, rotation, and angle immediately after impact) and the flight characteristics (distance, trajectory, and time). Various impact conditions were defined using 3 factors: the angles of the bat at impact projected to the horizontal and vertical planes, and the vertical inclination angle of the line of impact (the product of the sine of this angle and the radius of the ball determines the under-cut distance). Three-dimensional finite element analysis was used to construct a model of impact between a baseball and a wooden baseball bat and to conduct simulation analysis. The initial flight condition of the batted ball after the impact was determined for each simulated condition, and the flight distance was estimated from the initial flight condition. The results showed that a nearmaximum flight distance of 90-95 m was attained over a wide range of the opposite field when the bat head was not lowered substantially more than the grip-end. However, when the bat head was lowered substantially more than the grip-end, the flight distance attainable with the given impact condition decreased as the vertical bat angle increased, and the range of horizontal bat angle within which a great flight distance was attainable became narrower. The latter results suggest that a batsman needs to acquire a sophisticated technique with a greater precision of ball impact to hit a ball toward a given horizontal angle in the opposite field if the bat swing is characterized as lowering of the bat head to a large extent.

著者

矢内 利政 城所 収二 宮澤 隆 志村 芽衣

出版者

早稲田大学

雑誌

基盤研究(B)

巻号頁・発行日

2014-04-01

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通常のバッティングではバットの芯付近でボールの中心を打撃することにより高い打球速度が獲得でき、バントにおいてはバットの芯とそのやや先でボールの中心を打撃することにより打球速度は低くなるという現象を力学的に説明することを目的とした。その結果、①ヘッド速度が一定の条件でも、スイング速度と並進速度の組み合わせにより打球速度、及び打球速度を最大化するインパクト位置は変化することが明らかになった。これらの現象は, スイング角速度、重心速度、インパクト位置の条件の変化に伴いバットの反発係数が変動することに加え、ボールとバットが有する運動量が互いの間で転移する方向と大きさの変化により生じることが示された。