  We propose a class of microstructurally informed models for the linear
elastic mechanical behavior of cross-linked polymer networks such as the actin
cytoskeleton. Salient features of the models include the possibility to
represent anisotropic mechanical behavior resulting from anisotropic filament
distributions, and a power-law scaling of the mechanical properties with the
filament density. Mechanical models within the class are parameterized by seven
different constants. We demonstrate a procedure for determining these constants
using finite element models of three-dimensional actin networks. Actin
filaments and cross-links were modeled as elastic rods, and the networks were
constructed at physiological volume fractions and at the scale of an image
voxel. We show the performance of the model in estimating the mechanical
behavior of the networks over a wide range of filament densities and degrees of
anisotropy.
