棒球球棒甜蜜點的有限元素分析

Abstract

球棒甜蜜點的分析有助於了解如何有效的增加揮棒效能。甜蜜點有幾種不同的定義。本論文採用在相同揮擊條件下，使得球有最大離棒速度（Ball Exit Velocity，BEV）的擊球位置定義為球棒的甜蜜點。除了甜蜜點之外，我們也討論快速直球和曲球，何者較易被擊出全壘打，換言之，球被擊中後何者有較遠的飛行距離。 球的飛行距離除了牽涉到空氣動力學外，還受到球離棒時的狀態的影響。現今文獻中，較少有關於球離棒時運動狀態的研究。本論文利用有限元素法分析不同條件下球和球棒撞擊的過程。我們建立了滿足大聯盟規範的球與球棒的有限元素模型，並選擇球棒適當的邊界條件以模擬打擊者揮棒的過程。利用這個有限元素模型，我們比較不同定義下的甜蜜點的差異，探討影響BEV的重要因素，分析不同球路下球離棒後的飛行距離。

The analysis of the sweet point on a baseball bat is helpful to improve swinging efficiency. There are several different definitions of the sweet point. This thesis defines the sweet point as the place where the baseball acquires the maximum ball exit velocity under the same conditions. Besides the sweet spot, we also study the flying distance of the curve ball and fast ball, comparing which can easier hit homerun. Flying distance of baseball depends on not only the aerodynamic forces acting on the ball also the states of the ball leaving the bat. To the best of my knowledge, there are few studies focusing on the states of the ball when it leaves the bat. In this thesis, the finite element analysis is used to analyze the process of hitting a ball under different conditions. We built the finite element models of the ball and bats complying with the MLB regulation and set the proper boundary conditions for the bat when hitting the ball. With these models, we compared the sweet spots obtained using different definitions, investigated important factors affecting the ball exit velocity, and analyzed the flying distance of various kinds of pitches.