  Macroscale chains have been proposed to give insight into the physics of
molecular polymer systems. Nevertheless, understanding the rheological response
of systems of quasi-one-dimensional semiflexible materials, such as bead-chain
packings, is currently a great challenge. We study the nonlinear rheology of
random assemblies of macroscale chains -- including steel bead chains and
cooked spaghetti -- under oscillatory shear. We show that a universal
transition from localized to wide shear zones occurs upon increasing the strain
amplitude, for a wide range of lengths, flexibilities, and other structural
parameters of the constituent elements. The critical strain amplitude coincides
with the onset of strain stiffening development in the system. We obtain
scaling laws for transition sharpness, shear-zone width, and stiffness
enhancement as a function of chain length. Our findings suggest that the
entanglements between the constituent elements strengthen when approaching the
critical strain amplitude and rapidly become long range, even spanning the
entire finite system for long enough chains. We show that the nonlinear
rheological response is governed by the interplay between increasing stored
elastic forces due to entanglements and increasing contribution of dissipation
with shear rate and interlocking between chains.
