A Finite Element Model for the Prediction of Force Reduction of Athletics Tracks

Abstract The Force Reduction (FR) impact test, performed by means of an apparatus called artificial athlete, has been chosen by IAAF (International Association of Athletics Federations) as a standard to evaluate the performance of athletics tracks. The test procedure consists in dropping a mass on the sample, recording the evolution of the impact force and taking its maximum value normalized with respect to a reference one. In this work a Finite Element (FE) model of the FR test was developed to investigate the effects of sample thickness and material properties. Two athletics tracks and, for comparison, a sample of natural rubber were considered. Their mechanical behaviour was characterized, extrapolated to the strain rate of interest and modelled using hyperelastic constitutive equations. With data so derived a number of numerical (FE) simulations of the FR test on the three materials with varying thickness were performed. The FR values predicted by the simulations resulted to be in very good agreement with experimental FR data, particularly for thicknesses of practical interest. Finally, the suitability of an alternative model based on a linear elastic constitutive relationship was considered and results were discussed.