© 2006 isea Sports Engineering (2006) 9, 107–127 107 Chapter 1 Baseball An experimental investigation of baseball bat durability Patrick J. Drane, James A. Sherwood and Rebecca H. Shaw University of Massachusetts Lowell, USA The service life of a baseball bat is a function of its durability. All wood bats crack, and ash bats exhibit flaking of the barrel due to repeated impacts. In aluminum and composite bats, repeated impacts can cause a change in the material properties, which in turn can lead to dents and microcracks that ultimately coalesce to form macrocracks. A test machine for sim- ulating essentially any field condition for bat/ball impacts has been developed to study bat durability. The system uses an air cannon capable of firing a baseball at speeds up to 180 mile h –1 at a stationary bat which is supported in a grip that replicates a player’s hands. This paper will describe the system, present some supporting analysis of the gripping method, and present results of tests from wood and aluminum bats. Bending modes, damping, and the sensation of sting in baseball bats Daniel A. Russell Science & Mathematics Department, Kettering University, Flint, MI, USA The painful sensation of sting in the top hand of a player holding a baseball or softball bat may be a deterrent to enjoying the game, especially for young players. Several mechanisms for reducing the vibration of bending modes have been implemented in youth baseball bats in order to reduce sting. One method of assessing the effectiveness of these mechanisms is to compare the damping rate they provide for the first two or three bending modes in a bat. Damping rates are compared for several wood, aluminum, composite, and two-piece construction baseball bats, in addition to several bats with special damping control mechanisms. Experimental evidence suggests that damping mecha- nisms which reduce the vibration of the second bending mode are preferred by players. A novel dynamic absorber in the knob is shown to effectively reduce the vibration of the second bending mode and minimize the painful sting felt in the top hand. Experimental investigations of the relationship of baseball bat properties on batted-ball performance Rebecca H. Shaw and James A. Sherwood University of Massachusetts Lowell, USA Laboratory tests are used to investigate the relationship between baseball bat performance and two bat proper- ties: moment of inertia (MOI) and barrel stiffness for aluminum and composite bats. Each bat used in the current study is specifically designed and manufactured to isolate a particular property. Static tests, e.g. three- point bend and barrel compression, are used to characterize the properties of each bat. The natural fre- quencies of the bat are measured using modal techniques. Dynamic performance testing is done using an air cannon capable of throwing a baseball at collision speeds equal to those seen in field play. For the bats studied, variation in MOI contributed more to per- formance in the lab than did barrel stiffness. However, the changes in predicted field performance due to the two properties were similar. Abstracts from the 6th International Conference on the Engineering of Sport, 10–14 July 2006, Olympic Hall, Munich, Germany Volume 1 – Developments for sports The full papers are published in: Haake, S. and Moritz, E.F. (2006) The Engineering of Sport 6. Volume 1: Developments for Sports. Springer, New York, ISBN 0–387–31773–2.