Constitutive Equations

The purpose of this chapter is to present the theoretical backgroung of some handy general purpose theories and algorithms, that are provided in oofem in the form of general material base classes. They can significantly facilitate the implementation of particular material models that are based on such concepts. Typical example can be a general purpose plasticity class, that implements general stress return and stifness matrix evaluation algorithms, based on provided methods for computing yield functions and corresponding derivatives. Particular models are simply derived from the base classes, inheriting common algorithms.