  We analyze plane strain cold rolling processes, at large strains but slow
strain rates, by finite element modeling. At low temperatures, slow strain
rates, and moderate thickness reductions during rolling (at which Bauschinger
effect can be neglected for the particular class of polymeric films studied
here), the task of material modeling is greatly simplified, and enables us to
deploy a computationally efficient, yet accurate, finite deformation
rate-independent elastic-plastic material behavior (with inclusion of
isotropic-hardening). The finite deformation elastic-plastic material behavior
based on (i) hypoelasticity, and ii) multiplicative plasticity, are programmed
and carried out for cold rolling within Abaqus Explicit. Predictions from both
the formulations, i.e., hypoelastic and multiplicative decomposition, exhibit a
close match with the experimentally observed rolling loads. We find that no
specialized hyperlastic/visco-plastic material model is required to describe
the behavior of the particular blend of polymeric films, under the conditions
described here, thereby significantly speeding up the computation for
steady-state rolling simulations. Moreover, the use of classical rigid-plastic
modeling (which is often applicable to metals) is found to greatly
underestimate the rolling loads for polymers, due to large elastic stretches in
the polymer films at large strains.
