P-24 Study of humerus injury under impact loading for baseball

Abstract

In the United States and Japan, baseball is a very popular sport played by a great many people. However the ball used is hard and moves fast. A professional baseball pitcher in good form can throw a ball at up to 41.7m/s (150km/hr). If a ball at this speed hits the batter, serious injury is quite likely. In this paper we will describe our investigations of the impact of a baseball with living tissues by numerical methods and experiments. The experiments were done to characterize the material and structure of the baseball. Baseballs were fired at a load cell plate using a specialized pitching machine previously described in publications. The pitching machine had three rollers which were controlled by a neural network to produce a desired combination of linear and angular ball velocity vectors. The dynamic properties of the ball were determined by comparing the experimentally measured force history to a FE model. A different FE model representing a human humerus and surrounding tissue was then used in simulated impact experiments. The properties of the human tissues were not measured here were taken from published results. The dynamic finite element analysis was done by ANSYS/LS-DYNA. The results include an estimate of the peak stress in the bone and confirm what we know from experience - that a fast ball can cause a bone to break. Some methods to practicably reduce the severity of injuries in the game of baseball are also discussed.