A micromechanical study on sand − FRP interface subjected to cyclic loading

Fibre-reinforced polymer (FRP) is a promising composite to be used in construction in coastal and marine environments to resist seawater corrosion that deteriorates the properties of conventional civil engineering materials. A classical ground or seabed − structure interaction problem that is involved in the design of FRP structures, is however less understood when the soft nature of FRP is in subjection to the cyclic loadings from traffic, wind, wave and currents, causing penetration and abrasion at the soft FRP − soil interface. This study has downscaled the preceding problem into a micromechanical study at a benchmark sand grain − FRP interface. A large number of cyclic loading is applied, for the first time, at the sand − FRP composite interface, focusing on the development of the elastoplastic behaviour in the normal direction and the evolution of friction and energy dissipation in the tangential direction. The study combines the understanding from the tribology with the knowledge of civil engineering involved in the sand − FRP interaction, suggesting that a larger stick zone at the contact subjected to cyclic shearing is a key triggering of the simultaneous occurrence of the increased coefficient of friction and reduced damping ratio. © 2024 Elsevier Ltd.