It was recalled that dislocation patterns had been extensively studied by means of transmission electron microscopy. At the same time, theoretical approaches had been developed on the basis of reaction-diffusion schemes and computer simulation. The latter distinction was somewhat blurred, as some computer models included the former approach in their evolution equations. Regardless of their details, the aim of such studies was to consider simple dislocation patterns as being persistent slip bands and/or cellular organizations. Computer simulation involved a methodology which complemented other approaches. Nevertheless, the simulation conditions (cut-off procedure, periodic boundaries), had been extensively criticized and were responsible for spurious patterns. The simulations also did not clearly show the formation of cell structures. Moreover, the simulations did not yield the evolution of the dislocation patterns as a function of parameters such as the dislocation density, external force, or friction stress. The object of the simulations which were presented here was to study, at the mesoscopic scale, the formation of dislocation patterns in 2 dimensions. Systems were used which had large dimensions (20 x 20) and had rigid boundaries; which permitted the use of a cut-off procedure to be avoided. The simulations predicted the formation of dipolar walls in persistent slip bands, and clearly showed the formation of cell organization. For each pattern, relationships were deduced between the pattern size and parameters such as the dislocation density, external force, and friction stress. The results exhibited a good agreement with experimental laws.

R.Fournet, J.M.Salazar: Physical Review B, 1996, 53[10], 6283-90