Numerical investigations of the free surface effect in three-dimensional polycrystalline aggregates

► We model a polycrystal under fatigue loading using Finite Element Crystal Plasticity. ► We examine the local mechanical fields at the surface with a statistical analysis. ► In terms of plastic strain intensity, biaxial loadings are more critical. ► In terms of plastic strain spatial organization, biaxial loadings are more critical. ► Fatigue intrusion/extrusion steps at the surface are qualitatively modeled.