網球拍勁度對擊球時所產生動力學振動響應

Abstract

本研究是就網球拍質性的觀點去研究網球拍不同勁度(STIFFNESS)對擊球時產生的動力學振動響應。研究從運動員常採用的球拍中，隨機抽選DUNLOP IMPEDANCE，KENNEX DESTINY，PRINCE SPECTRUM COMP90，DUNLOP200 G，WIMBLEDON五種不同勁度球拍作為研究對象。每支球拍皆穿以台灣製的p.s尼龍線，直線張力是50磅，橫線張力是48磅。實驗時使用一部PRINCE廠牌professional Ⅱ with VSP型的發球機，以20.3±0.2公尺/秒之發球速度於距離拍面直線距離一公尺處發球撞擊拍面偏心位置。每一支球拍在垂直緊握狀況下，皆發球撞擊五十次，每次球拍受撞擊時，傳出拍柄之振動響應是透過美製GOULD牌LOAD-CELL BG-25應力測量儀以電壓形式傳送訊號資料，並配合美製GOULD多功能紀錄器，以及十六位元個人電腦安裝DASA電腦數位訊號處理軟體，將訊號作A/D轉換並紀錄實驗資料。實驗所獲得的訊號資料是使用頻譜分析的方式加以整理與分析。研究結果發現：勁度大的球拍垂直固定狀況受網球偏心撞擊時，傳出拍柄的振動響應，明顯的大於勁度小的球拍。

This study was undertaken determine clamped at prependicular degrees Dynamic Vibrational response of different stiffness of tennis racket due to Eccentric impact. The study were the DUNLOP IMPEDANCE racket and the KENNEX DESTINY and the PRINCE SPECTRUM COMP 90 racket and the DUNLOP 200G racket and the WIMBLEDON racket etc.. Five various rackets were strung with nylon string at tensions of the longitudinal 50 pounds and transverse 48 pounds. A Prince professional II with VSP tennis ball machine was used to fire 50 new Slazenger tennis ball from a distance of 1 meter at the Eccentric location of Transverse Axis. The ball velocity was caculated to be 20.3 ±0.2 m/sec at impact. Clamped at prependicular degree vibrational response of different stiffness of five various rackets was recorded through a GOULD RECORDER using a GOULD LOAD- CELL BG-25 transducer. But the data was transformed by A/D through the personal computer using DASA software. The experimential data was used Spectrum analysis. The results of this study was found: clamped at perpendicular degree vibrational response of stiffness of tennis racket due to Eccentric impact is higher than flexible of tennis racket.