SYMPOSIA PAPER Published: 01 January 1997

Dynamic Hardness (SDH) of Baseballs and Softballs


Impact research of soft materials has led to a new general dynamic hardness test method and hardness scale entitled the Scarton Dynamic Hardness (SDH) Method. Experimental impulse modal analysis testing is used to evaluate the transient or response characteristics of test materials such as sports equipment. The SDH method was used to evaluate and classify different types of sports balls by dynamic hardness and damping. A direct relationship was found between ball damping and the coefficient of restitution (COR). Sports safety applications show that a ball with a lower SDH has a reduced chance of inflicting head injury; if the SDH is too low, chest impacts may contribute to heart anomalies. Acoustical and impacter design research indicates that keeping the impacter resonances above the ball SDH will prevent their excitations. Subsequent reductions in acoustic “pinging” and enhanced performance are anticipated. The study included: baseballs, softballs, golfballs, racquetballs, marbles, ping pong, bowling, lacrosse, cricket, bocce, squash, tennis, and billiard balls.

Author Information

Giacobbe, PA
Rensselaer Polytechnic Institute, Troy, NY
Scarton, HA
Rensselaer Polytechnic Institute, Troy, NY
Lee, YS
Rensselaer Polytechnic Institute, Troy, NY
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Developed by Committee: F08
Pages: 47–66
DOI: 10.1520/STP11867S
ISBN-EB: 978-0-8031-5368-4
ISBN-13: 978-0-8031-2475-2