Experimental Evaluation of Shock Attenuation Properties of Sports Surface by Two-dimensional Impact Test

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, it was examined for hysteresis for three types of hardness samples. In this study, we improved the two dimensional impact test device and experiments were performed to three kinds of different samples. To evaluate the hysteresis properties of sports surfaces, the energy loss of each impact was calculated. As the results, Hysteresis property in the vertical direction was found to depend on the hardness of the sports surfaces. However, it was found that the hysteresis property in the horizontal direction is more complex than the vertical direction.