Flexural Vibration of Dakekanba Baseball Bat due to the Impact with Fast Pitched Balls – Comparison Tests with Sugar Maple, Aodamo, Yellow Birch and White Ash

Abstract

Dakekanba is the most popular broad leaf tree in Hokkaido. This study proposed the wood for manufacturing baseball bat. In order to compare the dakekanba wood with the others manufactured historically; sugar maple, aodamo, yellow birch, and white ash, full baseball bats with the same dimension were prepared from these woods. The performance of bat was studied by the impact test with fast pitched ball. The flexural vibration was measured by means of strain gauge. Results of the modal analysis showed that the first natural frequency was around 35 Hz and the second, 233 Hz, which were almost equal among these woods. The amplitudes of these modes increased with increasing the speed of pitched ball. As a result, the maple bat was the hardest in deflection and slowest in damping, and aodamo was the softest in deflection and the fastest in damping. It was concluded that these properties of dakekanba bat were close to those of yellow birch and white ash, which have served as intermediate between maple and aodamo.