  This article develops duality principles applicable to the non-linear
Kirchhoff-Love model of plates. The results are obtained through standard tools
of convex analysis, functional analysis, calculus of variations and duality
theory. The main duality principle concerns a convex (in fact concave) dual
variational formulation and related new optimality conditions for the model in
question. Finally, in the last section we develop some global existence results
for a similar model in elasticity.
