  FEpX is a modeling framework for computing the elastoplastic deformations of
polycrystalline solids. Using the framework, one can simulate the mechanical
behavior of aggregates of crystals, referred to as virtual polycrystals, over
large strain deformation paths. This article presents the theory, the finite
element formulation, and important features of the numerical implementation
that collectively define the modeling framework. The article also provides
several examples of simulating the elastoplastic behavior of polycrystalline
solids to illustrate possible applications of the framework. There is an
associated finite element code, also referred to as FEpX, that is based on the
framework presented here and was used to perform the simulations presented in
the examples. The article serves as a citable reference for the modeling
framework for users of that code. Specific information about the formats of the
input and output data, the code architecture, and the code archive are
contained in other documents.
