Contiuous-discontinuous modelling of hygrothermal damage processes in porous media.

Degradation of porous materials usually does not have a single identifiable cause, but results from the complex interaction between different types of degradation mechanisms. In the study at hand, both experimental and numerical methods are employed to gain insight herein. A novel continuous-discontinuous concept to model physical degradation of porous materials is put forward. It enforces a gradual transition between the continuous state before fracture occurs and the discontinuous state afterwards. The formulation covers both diffuse damage processes in the bulk material as well as the initiation and propagation of discrete cracks. Furthermore it describes in a generic way the impact of the development of a fracture on the transport of mass and energy in the porous material. Strategies to solve the resulting model equations III an optimal and accurate way are developed as well. Hereby, the advantages of a staggered solution scheme were exploited to respond dynamically to the specific needs of the different coupled systems of equations. The new algorithms allow minimizing the computational cost by optimizing both the temporal and the spatial resolution of the solution, without sacrificing accuracy. Simulations based on the continuous-discontinuous framework were compared to experimental data and a good agreement was found. Therefore the proposed methodology can be applied with confidence to tackle a wide range of potential applications