考虑相变的近场动力学热?力耦合模型及多孔介质冻结破坏模拟

多孔介质的传热传质现象广泛存在于自然界和工业领域中. 低温条件可能导致多孔介质中的组分发生相变, 并由此诱发材料损伤, 甚至导致结构失效破坏. 对这类破坏现象的预测需要精细化建模, 以能够反映物质的相变过程和材料的破坏特征. 本文采用热焓法改写经典的热传导方程, 在近场动力学框架下, 建立了一种考虑物质相变的热?力耦合模型, 发展了交错显式求解的数值计算方法, 进行了方板角冻结、热致变形和多孔介质冻结破坏等问题的模拟, 得到了方板的冻结特征、温度场和变形场的分布规律以及多孔介质的冻结破坏过程, 与试验和其他数值方法的结果具有较好的一致性. 研究表明, 本文所建立的考虑物质相变的近场动力学热?力耦合模型能够反映材料的非局部效应和物质相变潜热的影响, 准确捕捉相变过程中液固界面的演化特征, 再现多孔介质中材料相变、基质热致变形和冻结破坏过程, 突破了传统连续性模型求解这类破坏问题时面临的瓶颈, 为深入研究多孔介质冻融破坏过程和破坏机理提供了有效途径. 

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.