本文使用有限元素法分析棒球碰撞情形，探討甜蜜區上的擊球效果，以及改變球棒幾何參數對擊球效果的影響，並進一步探討揮擊參數變化對飛行射程的影響。研究方法是先用SolidWorks軟體建立模型後，在球棒不同位置處利用有限元素軟體LS-DYNA來模擬碰撞，並比較各處碰撞後的結果得出球棒甜蜜區確切位置，之後再變更球棒幾何參數，建立不同重量、長度、棒頭半徑的球棒，分別模擬撞擊，藉此探討在甜蜜區打擊下，球棒幾何參數變化對擊球效果的影響。最後改變揮擊角度和下切距離兩個揮擊參數，碰撞後的結果用數值法得出飛行軌跡，並分析改變揮擊參數對擊球距離的影響。對於棒球打者來說，可用本文結果快速了解球棒幾何特性以及揮擊資訊，作為日後挑選球棒或者調整打擊手感之參考。

The purpose of this study is to analyze baseball collision by using finite element method, and investigate batting effect on the sweet spot on the bat and then change the baseball geometry parameter. In addition, the researcher would like to investigate the effect of flight on batted ball by changing swing parameter. LS-DYNA is used to simulate collision on the different position on the bat after using SolidWorks to build modal, then compare the results to locate the exact position of sweet spot on the bat. By building different weight, length and radius of bat barrel, and simulate collision individually, the researcher wishes to investigate the influence of changing bat geometry parameter to batting effect on sweet spot. At last changing the undercut distance and bat swing angle, two of the swing parameter, to simulate collision, and the results of collision are used to get flight trajectory by numerical method, then analyze the influence of changing swing parameter to batted ball range. This study can provide bat geometry characteristic, swing information, and a reference for choosing a baseball bat, even help adjust batting feel for the batter.

誌謝 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 vii
表目錄 ix
第一章 緒論 1
1-1前言 1
1-2文獻回顧 1
1-3研究動機與目的 4
1-4研究方法 4
1-5使用軟體介紹 4
第二章 理論基礎 7
2-1 LS-DYNA顯式分析理論 7
2-2 棒球飛行射程推算 10
2-3 球棒的物理性質 13
2-3-1甜蜜區(Sweet Spot) 13
2-3-2轉動慣量(Moment of Inertia) 13
2-3-3 打擊中心(Center Of Percussion) 14
2-3-4恢復係數(Coefficient of Restitution) 16
第三章 有限元素模型與分析流程 17
3-1前言 17
3-2碰撞模擬之基本假設 17
3-3 棒球球棒模型設計 18
3-4 模型材料參數設定 20
3-4-1 棒球球棒 20
3-4-2 棒球 20
3-5 建立有限元素模型 22
3-6二維碰撞圖 25
第四章 結果與討論 26
4-1甜蜜區位置 26
4-1-1分析說明 26
4-1-2 分析結果 27
4-1-3 結果討論 30
4-2 球棒幾何參數分析 31
4-2-1 球棒重量 31
4-2-2 球棒長度 37
4-2-3 棒頭半徑 41
4-3 射程與揮擊角度及下切距離之關係 44
第五章 結論 54
參考文獻 56

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