  Networks of semiflexible or stiff polymers such as most biopolymers are known
to deform inhomogeneously when sheared. The effects of such non-affine
deformation have been shown to be much stronger than for flexible polymers. To
date, our understanding of non-affinity in such systems is limited to
simulations or specific 2D models of athermal fibers. Here, we present an
effective medium theory (EMT) for non-affine deformation of semiflexible
polymer and fiber networks, which is general to both 2D and 3D and in both
thermal and athermal limits. The predictions of this model are in good
agreement with both prior computational and experimental results for linear
elasticity. Moreover, the framework we introduce can be extended to address
nonlinear elasticity and network dynamics.
