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

The aim of the present paper is to investigate the consequences of the loading on the free surface response in polycrystalline aggregates. The study is made on a 316L stainless steel. Finite element computations using a crystal plasticity model are performed to simulate a polycrystalline aggregate submitted to different cyclic loadings. A statistical analysis of the results is carried out to extract information concerning the local stress and local strain fields at the free surface. The analysis of plastic strain localization on surface maps and inside the bulk through transparent volumetric views allows to exhibit the effects of the grain orientation and of the loading on local mechanical fields. The computation of an indicator characterizing extrusion/intrusion steps give some information on the initiation sites.