  In order to simulate the mechanical behavior of large structures assembled
from thin composite panels, we propose a coupling technique which substitutes
local 3D models for the global plate model in the critical zones where plate
modeling is inadequate. The transition from 3D to 2D is based on stress and
displacement distributions associated with Saint-Venant problems which are
precalculated automatically for a simple 3D cell. The hybrid plate/3D model is
obtained after convergence of a series of iterations between a global plate
model of the structure and localized 3D models of the critical zones. This
technique is nonintrusive because the global calculations can be carried out
using commercial software. Evaluation tests show that convergence is fast and
that the resulting hybrid model is very close to a full 3D model.
