Considerations of horizontal impact force applied to the long pile artificial turf

Abstract

The purpose of this study is to consider the two-dimensional impact force applied to the artificial turf with spike studs, especially focused on the horizontal impact force. The shock attenuation properties of sports surfaces are usually evaluated by reduction of maximum input force, for example, WA (World Athletics) adopted the EN14808 as the vertical force attenuation test. Otherwise, the horizontal impact attenuation has not been treated as the regulation of impact, although the most of impact in sports activities performed with diagonal impact force, including horizontal impact forces. In previous studies, we developed the two-dimensional impact test device with parallelogram structure which divide the vertical impact force to two-dimensional impact forces simultaneously. The impact test device can be set the various impact weights to generate the impact forces resembled to the ground reaction force in human running. And proposed the method for two-dimensional impact attenuation, named DFR (dynamic force reduction) because the horizontal impact forces were very dependent to the initial impact angle. Although the proposed method could evaluate the attenuation of various impact forces, there are some inappropriate cases especially in horizontal impact force attenuation. As the results, the horizontal impact force is very dependent to the impact angle and is independent to the vertical impact attenuation properties. Additionally, rubber chip as an infill material may cause increasing of horizontal impact force because it makes larger horizontal displacement in diagonal impact.