鋁製球棒振動特性之探討

Discussion on Vibration Characteristic of Aluminum Baseball Bat

王栢村(Bor-Tsuen Wang) ； 林秀卿(Hsiu-Ching Lin) ； 郭家榮(Jia-Rong Kuo) ； 沈君瑋(Jun-Wei Shen) ； 王廷維(Ting-Wei Wang)

《中華民國振動與噪音工程學會論文集》 2013 (2013/06) Pp. 336-341

摘要

本文主要針對鋁製球棒進行實驗模態分析（EMA），得到球棒結構之模態參數，包含自然頻率、阻尼比及模態振性。首先介紹EMA的概念及程序，並對鉛製球棒結構進行量測點之規劃，得到對應鋁製球棒結構之數學模型。傳統的EMA都使用衝擊鎚及加速規進行實驗量測，來得到量測之頻率響應函數（FRF）。再經由曲線嵌合軟體，得到實驗的模態參數。鋁製球棒是一個中空圓環型結構，此結構顯示兩種類型的結構模態振型，即為彎曲模態及圓環震型模態。透過模態振型的累加，得到鋁製球棒的振動特性和甜蜜區域。本文以中空圓環型之鋁製球棒結構進行實驗模態分析，並探討此結構之振動特性，其中顯示一個有效的方法，來確認甜蜜區域，未來可與有限元素分析搭配，進行模型驗證，得到等於實際結構之數學模型，達到快速的設計變更。

關鍵字

實驗模態分析（EMA） ； 球棒 ； 模態參數 ； 甜蜜區

並列摘要

This work aims to perform experimental modal analysis (EMA) on an aluminum baseball bat to obtain structural modal parameters, including natural frequencies, mode shapes and modal damping ratios. First, the principle and procedure of EMA are briefly introduced, respectively. The layout of measurement grid on the bat for EMA is arranged to visualize the structural mode shape accordingly. The conventional EMA by using the impact hammer and accelerometer is performed to measure the frequency response function (FRF). The experimental modal parameters can then be extracted. The bat is a hollow cylindrical shape and reveals two types of structural mode shapes, i.e. the bending modes and hoop modes. The vibration characteristics of the bat is examined and shown for the sweet spot area by summing the mode shape data. This work presents the experimental approach to study the vibration characteristics of a hollow type of baseball bat and shows an effective method to identify the sweet spot Finite element analysis can be adopted in the future to construct the analytical model for bat design simulation.

並列關鍵字

experimental modal analysis (EMA) ； baseball bat ； modal parameter ； sweet spot