  Quasi-static tensile experiments were performed for a model disordered solid
consisting of a two-dimensional raft of polydisperse floating granular
particles with capillary attractions. The ductility is tuned by controlling the
capillary interaction range, which varies with the particle size. During the
tensile tests, after an initial period of elastic deformation, strain
localization occurs and leads to the formation of a shear band at which the
pillar later fails. In this process, small particles with long-ranged
interactions can endure large plastic deformations without forming significant
voids, while large particles with short-range interactions fail dramatically by
fracturing at small deformation. Particle-level structure was measured, and the
strain-localized region was found to have higher structural anisotropy than the
bulk. Local interactions between anisotropic sites and particle rearrangements
were the main mechanisms driving strain localization and the subsequent
failure, and significant differences of such interactions exist between ductile
and brittle behaviors.
