A multi-physics model for cyclic loading

The presence of water significantly influences the cyclic response of porous materials due to the activation of molecular forces and surface energy phenomena. Among other effects, moisture causes a decrease in stiffness and a reduction of the tensile strength of the material. Cyclic loading is characterized by stiffness degradation and the occurrence of permanent deformations after unloading. All these phenomena can be adequately described by a combined damage-plasticity model coupled to a moisture transport model. In the present paper we will first derive the governing equations for a discrete damage-plasticity model and discuss their implementation in a fully coupled multi-physics model. The capabilities of the coupled model and the effects of moisture on the cyclic response of porous materials will be illustrated with two numerical examples.