The global, intergranular and intragranular responses of a polycrystalline
aggregate are investigated. It is shown that the heterogeneity of stress an
d strain dramatically increases from the global to the local level. Plastic
deformation structures develop on a scale larger than the grain. Several t
ypes of boundary conditions are applied to polycrystalline aggregates, in o
rder to estimate the importance of the surface effect. The results obtained
are presented as contour plots on the cube, and a detailed study is perfor
med to relate the variation obtained with the orientation of the grain and
the position in the aggregate. (C) 2001 Elsevier Science Ltd. All rights re
served.