This article presents a numerical model coupling the finite difference method and discrete element methods (FDM, DEM) for simulating the response of cellular geostructures to impacts. DEM is used in the vicinity of the impacted area while FDM is used far away. The continuity between the DEM and FDM domains is insured using the edge-to-edge method. The numerical parameters are calibrated based on compression and impact experiments conducted on elementary cells. Numerical simulations at the structure scale are compared with real-scale experimental data. The response of the structure is addressed varying the impact conditions. The projectile shape and the position of the impact point appear to be the most influential parameters.