The nonlinear membrane energy: variational derivation under the constraint “det∇u>0”

In [Anza Hafsa, O., Mandallena, J.-P., The nonlinear membrane energy: variational derivation under the constraint “det∇u≠0”, J. Math. Pures Appl. 86 (2006) 100–115] we gave a variational definition of the nonlinear membrane energy under the constraint “det∇u≠0”. In this paper we obtain the nonlinear membrane energy under the more realistic constraint “det∇u>0”.