In a response to reverse the trend of a perceived increase in multi-piece failures (MPFs) of wood baseball bats in Major League baseball games, the Office of the Commissioner of Baseball implemented changes to the Wooden Baseball Bat Specifications (WBBS) in December 2008. These changes introduced bat-supplier regulations that outlined strict quantitative requirements for wood quality and instituted a third-party inspection of professional wooden baseball bats for the 2009 season. Additional changes to the WBBS for the 2010, 2011, and 2012 seasons targeted increasing the density of the wood used to make maple bats, thereby increasing the minimum breaking strength of the wood allowed for these bats. By the completion of the 2014 season, these changes had driven a 65% reduction in the rate of MPFs per game relative to the 2008 season. It is hypothesized that the rate of MPFs can be further reduced if regulations on the allowable geometries of the taper region for the bats used by MLB teams are implemented. To develop a fundamental understanding of the relationship among (1) the angle of the taper (2) the starting point of the taper along the length of the bat, and (3) wood density, a series of generic bat profiles that were subjected to bat/ball impacts was investigated using LS-DYNA. In this paper, the results of these bat/ball impact simulations are shared, and a summary of the various combinations of these geometric parameters on bat stress and strain is presented. The durability information gained from these generic bat profiles is then used to give guidance in understanding why certain bat profiles used in professional baseball have relatively high rates of MPFs while other profiles exhibit a relatively low rate of MPFs.
Fortin-Smith, J., Sherwood, J., Drane, P., & Kretschmann, D. (2016). A Finite Element Investigation of the Relationship between Bat Taper Geometry and Bat Durability. In Procedia Engineering (Vol. 147, pp. 419–424). Elsevier Ltd. https://doi.org/10.1016/j.proeng.2016.06.333