“…Exact discrete energy conservation does not guarantee unconditional stability for the non linear case, but definitely enhance it, as it has been widely reported in the literature (Stuart and Humphries, 1996;García Orden and Dopico Dopico, 2006). This is the main motivation behind this work, that aims to extend a previously developed conserving penalty formulation Goicolea and García Orden, 2000;García Orden and Goicolea, 2001), which showed excellent stability properties, to the augmented Lagrangian formulation, which is the main contribution of this paper and it is developed in Section 3.2.…”