  The effect of grain size on the flow strength of FCC polycrystals was
analyzed by means of computational homogenization. The mechanical behavior of
each grain was dictated by a dislocation-based crystal plasticity model in the
context of finite strain plasticity and takes into the account the formation of
pile-ups at grain boundaries. All the model parameters have a clear physical
meaning and were identified for different FCC metals from dislocation dynamics
simulations or experiments. It was found that the influence of the grain size
on the flow strength of FCC polycrystals was mainly dictated by the similitude
coefficient $K$ that establishes the relationship between the dislocation mean
free path and the dislocation density in the bulk. Finally, the modelling
approach was validated by comparison with experimental results of the effect of
grain size on the flow strength of Ni, Al, Cu and Ag.
