1aSA5. Vibration damping mechanisms for the reduction of sting in baseball bats

Session: Monday Morning, Oct 22

Author: Daniel A. Russell
Location: Graduate Program in Acoustics, Pennsylvania State University, 201 Applied Science Bldg, University Park, PA 16802drussell@engr.psu.edu


When the impact between a baseball and a bat occurs outside the “sweet-spot” region, the resulting vibration in the handle often produces a stinging sensation in the hands. Pain from a poorly hit ball is primarily felt in the fleshy web between thumb and forefinger in the top (distal) hand, and also to a lesser degree in the heel of the bottom (proximal) hand, and the sensation of sting is more prevalent in aluminum bats than in wood. Several bat manufacturers have attempted to minimize handle vibration in aluminum bats through various methods including handle grips, foam injected into the hollow handle, two-piece construction joining composite handles to aluminum barrels, and the insertion of vibration absorbers in the taper region and in the knob of the handle. This paper will assess and compare the performance of several such vibration damping applications implemented in baseball bats. Experimentally measured damping rates corresponding to the bending mode shapes responsible for sting will be compared for a variety of bat designs. The effectiveness of available commercially implemented damping mechanisms will be compared using frequency response functions and time signals.