Elastic behaviour of sport surface materials

Abstract

During locomotion, the contact forces between the foot and ground are three-dimensional. However, previous studies quantifying the force-deformation behaviour of shoe and/or surface materials have involved single, uniaxial tests. Many of these studies have also been subject to errors due to boundary conditions. Elastomeric foams used in sport shoes and surfaces are highly compressible and nonlinear, and behave differently under tension and compression. Therefore, the purposes of this paper were to develop an objective set of measures to determine the three-dimensional elastic behaviour of these materials, and to use the method to quantify the behaviour of three materials used in a specific synthetic running track. Unconfined compression and tension, and confined compression loading tests were performed on standard-sized samples. Longitudinal and transverse stretch were determined from the loading apparatus and/or from analysis of images taken during the test. Nominal stress was calculated from original cross-sectional area and loading force. A method to determine the bimodal, nonlinear and compressible behaviour of the materials used in sport shoes and surfaces has not been presented before. This study is the first to quantify the complete elastic behaviour for materials used in running surfaces.