IMPACT BEHAVIOUR OF THE BASEBALL WITH IMPLICATIONS FOR PLAYER SAFETY

Fatalities amongst baseball pitchers occur primarily as a result of impact by the balled ball (Adler & Monticone, 1996). It was hypothesized the material properties of the baseball would affect ball exit velocity after bat-ball impact, and thereby the available time for the pitcher to take evasive action. Material behaviour of the baseball under conditions representative of those during bat-ball impact have not been previously investigated. The results of quasi static compression testing were used to develop a mathematical model of the nonlinear viscoelastic behaviour of the baseball as the basis for dynamic analysis of the bat-ball impact. KEY WORDS: baseball, material properties, infielder injury. INTRODUCTION: In 1997, baseball had the highest fatal injury rate of the 13 sports undertaken by men in US colleges, exceeding that of both spring football and ice-hockey (Dick, 1999). Impact from the batted ball is the primary cause of deaths among baseball pitchers (Adler & Monticone, 1996). The use of increasingly sophisticated metal bats has been proposed as a factor in ball exit velocities which exceed the reaction time of pitchers in the field (Crisco