Effect of material properties on hitting point on ball rebound for rubber baseball bats

Abstract

The objective of this study was to construct a finite element (FE) model for a rubber baseball bat which can accurately simulate the behavior of baseball impact, and to investigate the effect of mechanical properties of the hitting area on the rebound of a ball, by conducting FE analysis. FE models of an aluminum bat and a bat which is composed of urethane for hitting area were constructed. The material model for urethane with non-linearity was expressed based on the result of the static tensile and compression tests and a drop weight impact test to represent the strain rate dependency and energy absorption characteristics. The simulation results for the rebound velocity of the ball, which were calculated from impact analyses between the urethane plate and the ball with hyperelasticity, qualitatively agreed well with the experimental results. FE analyses were conducted with the ball model and the bat models which introduced the material models with different forming rate of urethane to the hitting area. From these results, the rebound velocity of the ball tends to depend on the ball impact velocity as well as the forming rate of urethane. The tendency suggests that the ball rebound velocity is involved in the deformation behavior of the ball, especially the deformation velocity to restore the ball deformation.