On the formulation of evolutive laws and complementarity conditions for non-smooth elastoplastic materials

In the present work a formulation of evolutive laws and complementarity conditions in non-smooth elastoplasticity is discussed. The treatment addresses the problem of non-smooth elastoplasticity which is represented by functions characterized by singularities and defined by non-smooth yielding limit conditions and non-differentiable functions. The mathematical theory of subdifferential calculus is properly advocated to provide the suitable mathematical framework in order to treat non-differentiable functions and non-smooth problems. Extended expressions of evolutive laws and complementarity conditions in non-smooth elastoplasticity are illustrated within the adopted generalized mathematical treatment. Relations between the presented mathematical formulations and the expressions in classical elastoplasticity are pointed out and discussed. The proposed treatment has significant advantages since it provides a geometrical framework to the maximum dissipation principle for non-smooth problems in elastoplasticity. Furtherly, the proposed treatment gives insights in the interpretation of the adopted geometrical framework for different types of evolutive laws for new materials and solids such as for instance in some types of new metamaterials with non-smooth constitutive behavior. In addition, the present formulation is also useful in the design of metamaterials, such as pantographic ones, where the plasticity of the pivots is relevant.