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The present paper is aimed at clarifying the dependence of the force reduction ability of sport surfaces used in athletic tracks on the material’s viscoelastic properties and on the geometry of the sample. The study is based on laboratory tests carried out with an “artificial athlete” apparatus and dynamic mechanical analysis. Seven different sport surfaces were tested; other polymeric materials were also examined in order to widen the property ranges covered. The results show a prominent effect of sample thickness on the measured value of force reduction; a method to relate it to the intrinsic properties of the material is proposed

In this work the possibility of predicting the Force Reduction (FR) characterizing the shock absorption capability of track surfaces by finite element modeling was investigated. The mechanical responses of a typical sport surface and of a reference material were characterized by quasi-static uniaxial compression experiments and fitted by Neo-Hookean and Mooney-Rivlin's hyperelastic models to select the more appropriate one. Furthermore, in order to examine the materials behavior at strain rates typical of athletics applications, the rate dependence of the constitutive parameters was investigated. A finite element model, taking into consideration the post-impact nonlinear dynamics of the track surface and of the system (track surface + artificial athlete), was developed and validated through comparison with the results of FR tests. The simulations showed a very good agreement with the experiments and allowed to interpret the experimentally observed combined effect of track thickness and material intrinsic properties on the overall surface behavior.Manuscript (excluding authors' names and affiliations) 1

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