On the formulation of isotropic and anisotropic damage

Considerable effort has been devoted in recent years to the formulation of degradation and damage. A large portion of the models, however, still correspond to variations of the traditional ``(1-D)-type'' scalar damage formulation, while a smaller portion represents other kinds of isotropic or anisotropic degradation. In previous papers the authors proposed a general unified framework for degradation and damage which is similar in terminology and notation to the well-known theory of elasto-plasticity. In the present paper, that theory is briefly revisited, and new more general formulations of isotropic as well as anisotropic damage are described within the same framework.