Abstract

The choice of materials used to make baseball bats has evolved over the years from traditional solid wood to aluminium and now to composites. To determine whether or not a bat’s design is in compliance with the batted-ball performance standard for a given league, a new bat is tested in a hitting machine where the bat is subjected to a limited number of hits. Considering the material behaviour that occurs within a composite material subjected to numerous impacts, the batted-ball performance of composite bats can theoretically improve with use as the polymer-matrix develops microcracks. These microcracks can soften the barrel of the bat which may allow the trampoline effect to increase. As the trampoline effect increases, there is potential for the batted-ball speed to increase. This paper will discuss the observed evolution of the performance for six currently popular composite baseball bats that were subjected to cycles of performance testing followed by repeated use in a controlled laboratory setting. None of the six composite baseball bats exhibited a significant change in performance. Some of the composite bats did exhibit poor durability. Verf.-Referat