2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/102111In [4] we gave a variational definition of the nonlinear membrane energy under the constraint "det\nabla u\not=0". In this paper we obtain the nonlinear membrane energy under the more realistic constraint "det\nabla u>0".Classical Analysis and ODEs49J45, 74K15The nonlinear membrane energy: variational derivation under the constraint "det\nabla u>0"text