SOFTBALL BAT VIBRATIONS DURING 'THE SWING AND IMPACT: A PRELIMINARY ANALYSIS OF EMPIRICAL DATA

Abstract

The purpose of this study was to investigate softball bat vibrations during the swing and impact and to correlate the vibrations with characteristics of hitters and the swing. Four recreation-league college males and four females aged 21-23 yrs hit 15-25 pitched softballs with a high-performance aluminium softball bat (34 in, 28 oz). Analysis of strain gauge and videotaped records of 112 trials indicate that: 1. The frequency of bat oscillations during the swing ranged from 4.1 to 7.5 Hz, significantly below the 13 Hz of the lowest vibration mode of the clamped boundary condition; and 2. All hitters consistently demonstrated the effective utilisation of the diving board mode of vibration in timing the impact and swing such that the bat was 'releasing' elastic energy at impact that was stored during the swing.