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10:20   Baseball; bat and catcher mask design Chair: Hiroki Okubo 10:20 20 mins A FINITE ELEMENT INVESTIGATION OF THE RELATIONSHIP BETWEEN BAT TAPER GEOMETRY AND BAT DURABILITY Joshua Fortin-Smith, James Sherwood, Patrick Drane, David Kretschmann Abstract: In response to a perceived increase in multi-piece failures (MPFs) in professional baseball bats, the Office of the Commissioner of Baseball implemented changes to the Wooden Baseball Bat Specifications (WBBS) in December of 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. An additional change 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 MPFs relative to the 2008 season. It is hypothesized that the level of multi-piece failures 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 starting point of the taper along the length of the bat, (2) the angle of the taper and (3) the diameter at the start of the taper, a series of finite element models of bat/ball impacts was completed in LS-DYNA for a generic bat. Bat/ball impacts were completed for three critical impact positions along the length of the bat. 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 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 a high rate of MPFs while other profiles exhibit a low rate of MPFs. 10:40 20 mins EVALUATION OF CATCHER MASK IMPACTS Patrick Schwizer, Marc Demierre, Lloyd Smith Abstract: Concussion awareness in sports-related injuries has increased over the past decade. This has resulted in improvement in protective equipment and in our understanding of head injury. While contact sports such as ice hockey or football are of interest, concussion also occurs in non-contact sports like softball and baseball. The aim of this project was to describe facemask response to ball impacts. The study involved one face mask design and two types of foam padding. A method is presented that allows foam characterization at deformation rates and magnitudes representative of impact conditions. The foam impacts were modelled numerically and shown to agree with experiment. The facemask/foam system was placed on a Hybrid III headform and impacted with softballs to measure its response experimentally. A numeric model of the facemask/foam system on a model of the Hybrid III headform showed good agreement with experiment. Facemask impacts with a stiffer foam showed superior attenuation at high speeds (above 31 m/s) while a softer foam attenuated impacts better at low speeds. 11:00 20 mins WOOD BASEBALL BAT MODELING TO DETERMINE A SCORE TO PREDICT THE RELATIONSHIP BETWEEN BAT PROFILE AND DURABILITY Joshua Fortin-Smith, James Sherwood, Patrick Drane, David Kretschmann Abstract: Major League Baseball (MLB) currently has few restrictions on baseball bat profiles allowed for use during gameplay. Although current multi-piece failure (MPF) rates are at their lowest in years, there is still room for further improvement by regulating the bat profiles allowed in games. The influence of bat profile tapering was analysed utilizing finite element models of various known profile geometries to determine the effect on bat durability. LS-DYNA simulations were processed for profiles over a range of maple wood densities that would be currently allowed by MLB regulations. This paper will describe in detail the various modelling studies conducted to determine the factors that comprise a bat profile of good durability. The results of the modelling are compared to on-field data of bat failures during gameplay of known profiles used by MLB players. A profile score is proposed that is a combination geometrical characteristics and wood density. This score is a good predictor of the relative durability of a given bat configuration.