“…When nonlinearities are restricted to the boundaries, small-strain concept is adopted, and the material in the bulk is linear and homogeneous (so that the fundamental solutions of the underlying operators are at disposal), the Boundary Element Method (BEM) can be an efficient and very accurate alternative to the Finite Element Method (FEM) usually employed in engineering computations, e.g. [13,21,22,25,27,29,31,58]. In this paper, we confine ourselves to the mentioned situation in the bulk, so that all nonlinearities arising from the normalcompliance model and the Coulomb friction will be indeed only on the boundary or interfaces between the bodies.…”