Fig. 1.
Confined compression stress relaxation analysis in plane strain. The prescribed displacement uy on the top surface has a ramp-and-hold profile, with a ramp rate of -10-4 mm/s and a final displacement of -0.5 mm. (a) The contact model consists of two slabs constrained as shown (slab width = 12 mm, height = 2 mm). The top slab has 5×12 uniformly spaced elements; the bottom slab has 3×28 elements, with a mesh bias in the vertical direction to accommodate the boundary layer anticipated at the free-draining bottom surface. (b) The no-contact model consists of a single slab (width = 12 mm, height = 4 mm) with 3×40 elements and a mesh bias in the vertical direction in the bottom half, replicating the mesh distribution of the contact model in (a) along the vertical direction.