Comparison of dynamic elasticity between two types of new material plastic table tennis ball: taking DHS D40+ and Nittaku 40+ as an Example

Background: Nittaku 40+ and DHS D40+ are two different brands of new plastic balls, both of which are designated as official match balls and widely used in international events. Due to the change of material and diameter from traditional celluloid table tennis ball to new plastic ball, the hardness and elasticity of the new plastic ball also change accordingly. The purpose of this study is to analyze the difference of the dynamic elasticity between the two brands of new plastic ball, taking Nittaku 40+ ball and DHS D40+ ball as an example. Method: Self-made experiment was designed to generate different levels of initial speed of table tennis ball to test the dynamic elasticity characteristics of DHS D40+ and Nittaku 40+. A high-speed camera was used to collect the trajectory of ball falling and rebound after hitting the table during the experiment, and the Kinovea software was used to process the falling and rebound trajectory and calculate the average speed of falling and rebound process, then accordingly calculate the rebound speed decrement rate. Results: : Results showed that the rebound speed and decrement rate of DHS D40+ and Nittaku 40+ both increased with the increase of falling speed, respectively. When falling at slow and medium speeds, there was no significant difference of dynamic elasticity between DHS D40+ and Nittaku 40+. When falling at high speed, there was a significant difference of dynamic elasticity between DHS D40+ and Nittaku 40+. Conclusion: Compared with the DHS D40+, the Nittaku 40+ has bigger hardness and brittleness, and the sphere structure is more uniform, featuring better dynamic elasticity stability and rebound height.