On uniqueness for frictional contact rate problems

A linear elastic solid having part of the boundary in unilateral frictional contact with a stiffer constraint is considered. Bifurcations of the quasi static velocity problem are analyzed, making use of methods developed for e lastoplasticity. An exclusion principle for bifurcation is proposed which i s similar, in essence, to the well-known exclusion principle given by Hill( 1958). Sufficient conditions for uniqueness are given for a broad class of contact constitutive equations. The uniqueness criteria are based on the in troduction of 'linear comparison interfaces' defined both where the contact rate constitutive equation are piece-wise incrementally linear and where t hese are thoroughly nonlinear. Structural examples are proposed which give evidence to the applicability of the exclusion criteria. (C) 1999 Elsevier Science Ltd. All rights reserved.