  Most of crystalline materials develop an hysteresis on their deformation
curve when a mechanical loading is applied in alternating directions. This
effect, also known as the Bauschinger effect, is intimately related to the
reversibile part of the plastic deformation and controls the materials damage
and ultimately their failure. In the present work, we associate mesoscale
Dislocation Dynamics simulations and Finite Element simulations to identify two
original dislocation mechanisms at the origin of the traction/compression
asymmetry and quantify their impacts on the cyclic behaviour of FCC
single-crystals. After demonstrating that no long-range internal stresses can
be measured in the simulations, careful analysis of the dislocation network
show that the Bauschinger effect is caused by an asymmetry in the stability of
junctions formed from segments whose curvature is determined by the applied
stress, and a significant portion of the stored dislocation segments is easily
recovered during the backward motion of dislocations in previously explored
regions of the crystal. These mechanisms are incorporated into a modified
crystal plasticity framework with few parameters quantified from statistical
analysis of Dislocation Dynamics simulations or from the literature. This
strategy has a real predictive capability and the macroscale results are in
good agreement with most of the experimental literature existing on the
Bauschinger and cyclic deformation of FCC single-crystals. This work provides
valuable mechanistic insight to assist in the interpretation of experiments and
the design of structural components to consolidate their life under cyclic
loading.
