Abstract
Shock attenuation property of sports surfaces is especially important not only for the athlete's performance but also for injury prevention. To evaluate the properties of the sports surfaces, some sports governing bodies often adopt friction tests and shock attenuation tests to determine the horizontal and vertical characteristics, respectively. Although the diagonal impacts are often observed in athletic sports, shock attenuation test only treats the vertical impact test. Therefore we developed a two-dimensional impact test device for examining the two-dimensional cushioning characteristics of sports surfaces in previous studies. To produce a simultaneous two-dimensional force against a test specimen, we incorporated a parallelogram linkage in the measuring system. In previous study, three different hardness of surfaces were examined for calculating the FR (Force Reduction) values not only the vertical component but also the horizontal component. As the results, Vertical FR values were increased with increasing the initial angle and impact intensity in all surfaces. And the different patterns of horizontal FR values were observed in these surfaces. In this study, we evaluated vertical and horizontal displacement by two-dimensional impact tests with high-speed video analysis. And we evaluated hysteresis properties of sports surfaces. As the results, horizontal properties of sports surfaces might depend on not only the material but also the structure of the specimen.
