Evaluating baseball bat performance

Abstract

Selected methodologies currently used to assess baseball bat performance were evaluated through a series of finite element simulations. Results of the comparison show that current test methods contradict one another and do not describe the performance advantage of modern hollow bats over solid wood bats. The discrepancy was related to the way performance was quantified and the way the bat was tested. Performance metrics that do not consider a bat’s mass moment of inertia (MOI) were observed to underestimate the hitting performance of light weight bats. A bat’s centre of percussion was observed to be an unreliable indicator of its sweet spot (i.e. impact location providing the maximum hit ball speed). Bat performance was found to be sensitive to the relative impact speed between the bat and ball. From these observations three recommendations concerning bat performance were made: (1) performance should be measured at relative speeds between the bat and ball that are representative of play conditions; (2) the ball should impact the bat at its experimentally determined sweet spot; and (3) performance should be quantified from ball and bat speeds before and after impact. Using current test methods, an aluminium bat had a 0.9% higher performance over wood (maximum), while using the proposed recommendations the difference was 3.8% (average). The variation in the relative performance over three test conditions reduced from a 4% using current test methods to a 0.3% when the above recommendations were followed.