Constrained deformation of a confined solid: anomalous failure by nucleation of smectic bands

We report results of computer simulations of the deformation and failure behavior of a thin crystalline strip of "hard disks" in two dimensions confined within a quasi-one-dimensional "hard-wall" channel of fixed width corresponding to a few disk diameters. Starting from a commensurate triangular solid, stretching the strip along its length introduces a rectangular distortion. This, beyond a critical strain, leads to failure of the solid by "phase separation" into alternating bands of solid and smectic-like phases. The critical strain is inversely proportional to the channel width, i.e., thinner strips are stronger. The large plastic deformation which precedes failure is observed to be reversible.