Abstract: We address the Sobolev?Neumann problem for the bi-harmonic equation describing the bending of the Kirchhoff plate with a traction-free edge but fixed at two rows of points. The first row is composed of points placed at the edge, at a distance ?>0 between them, and the second one is composed of points placed along a contour at distance O(?1+?) from the edge. We prove that, in the case ??[0,1/2), the limit passage as ??+0 leads to the plate rigidly clamped along the edge while, in the case ?>1/2, under additional conditions, the limit boundary conditions become of the hinge support type. Based on the asymptotic analysis of the boundary layer in a similar problem, we predict that in the critical case ?=1/2 the boundary hinge-support conditions with friction occur in the limit. We discuss the available generalization of the results and open questions.
