Abstract
Rubber-ball baseballs are softer than the balls used as official baseballs in Japan. When rubber balls are hit by a baseball bat, the dynamic property of the rubber ball is complicated, because the impact deformation of a rubber ball is larger than that of an official ball. In this study, it was proposed that a composite bat has a high hitting performance when used with a rubber-ball baseball. The materials of this composite bat include an aluminum alloy in the barrel part, a CFRP (Carbon Fiber Reinforced Plastics) in the grip part, and it was coupled with a polycarbonate in between both parts. The hitting performances of the proposed bat and a metal bat (aluminum alloy in all parts) were simulated using finite element analysis. Through hitting simulations, ball types were examined with no-spin (knuckle ball) and back-spin (fastball) pitches, and vertical offset distances (height of the center distance between the bat and ball) were changed from 0 to 20 mm. From the results of the simulation, the composite bat was bending more than the metal one at the point of collision with the pitched ball. In the case of the back-spin ball pitch being hit by the composite and metal bats, the vertical angle of the ball after being hit was decreased approximately 3.0 degrees in comparison with the no-spin ball.
