This paper deals with the study of a nonlinear problem of frictional contac
t between an elastic body and a rigid foundation. The elastic constitutive
law is assumed to be nonlinear and the contact is modelled with Signorini's
conditions and a version of Coulomb's law of dry friction. We present two
weak formulations of the problem and establish existence and uniqueness res
ults, using arguments of elliptic variational inequalities and a fixed-poin
t property. Moreover, we prove some equivalence results and study the behav
iour of the solution when the coefficient of friction tends to zero.