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 treats only 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 this study, two kinds of cushioned and an non-cushioned impact tests were examined to calculate the FR(Force Reduction) values not only in vertical but also in horizontal impact force. And the maximum deformations of impact tests were also acquired by the high-speed video analysis. As the results, both of vertical and horizontal impact forces which varied with initial impact angle and drop height were well represented by quadratic surface. Therefore vertical and horizontal FR value of two kinds of surface were calculated from the experimental maximum force and estimated impact force with the same height and initial angle. Futhermore, the horizontal maximum deformations are strongly related to the initial angle of the impact force because the horizontal impact force increases sharply with increasing the initial angle of the impact.
The Proceedings of Joint Symposium: Symposium on Sports Engineering, Symposium on Human Dynamics
