The paper is divided into two parts. In the first part the authors derive an implicit variational inequality, being the weak (variational) formulation of the boundary value problem for a linear elastic body in a frictional contact with a rigid support on a part of the boundary. Applying a general duality theory to Signorini’s problem with friction, they obtain the quasi-variational inequality defined on the surface of a possible contact only and expressed in terms of stresses.
The second part of the paper concerns the dual formulation of the obstacle problem for a von Kármán plate. In an earlier paper the authors have formulated the dual obstacle problem in terms of static and kinematic fields [see ibid. 37, 135-141 (1985; Zbl 0578.73051)]. In the paper under review they propose a novel approach to the same dual obstacle problem in which a kinematic field is not explicitly present.