PERIDYNAMIC THERMOMECHANICAL COUPLING MODEL WITH PHASE CHANGE AND SIMULATION OF FREEZING FAILURE OF POROUS MEDIA

A wide range of natural and industrial processes involve the phenomenon of heat and mass transport in porous media. At low temperatures, the transported substance in porous media may undergo a phase change, which may induce material damage and even lead to structural failure. The prediction of this kind of failure phenomenon needs refined modeling to reflect the phase change process and the failure characteristics of materials. In the framework of peridynamic, the classical heat conduction equation is rewritten by using the enthalpy method, a thermal-mechanical coupling model considering the phase transition of substances is established, and the numerical calculation method of staggered solution is developed. The following problems are simulated with the established model, including the angular freezing of square plates, the thermally induced deformation of square plates, and the freezing failure of porous media. The phase transformation characteristics, temperature, deformation distribution of square plate freezing, and the freezing failure process of porous media are obtained by simulation, which are in good agreement with the results of experiments and other numerical methods. The research shows that the peridynamic thermomechanical coupling model established in this paper can reflect the nonlocal effect of materials and the influence of the latent heat of material phase change, accurately capture the evolution characteristics of the liquid-solid interface during the phase change process, and reproduce the process of material phase change, thermal deformation of matrix and freezing failure in porous media. This method breaks through the bottleneck of the traditional continuity model in solving this kind of failure problem and provides an effective way for in-depth research on the freezing and thawing failure process and failure mechanism of porous media.