  The dynamics of dislocation assemblies in deforming crystals indicate the
emergence of collective phenomena, intermittent fluctuations and strain
avalanches. In polycrystalline materials, the understanding of plastic
deformation mechanisms depends on grasping the role of grain boundaries on
dislocation motion. Here the interaction of dislocations and elastic, low angle
grain boundaries is studied in the framework of a discrete dislocation
representation. We allow grain boundaries to deform under the effect of
dislocation stress fields and compare the effect of such a perturbation to the
case of rigid grain boudaries. We are able to determine, both analytically and
numerically, corrections to dislocation stress fields acting on neighboring
grains, as mediated by grain boundary deformation. Finally, we discuss
conclusions and consequences for the avalanche statistics, as observed in
polycrystalline samples.
