A Computational Model for the Thermal Spallation of Crystalline Rocks

Thermal spallation is the erosion of brittle materials subjected to high heat fluxes, such as a hot fire in a concrete structure. While experimental investigations provide valuable data on the spallation process, they lack generality to be extrapolated to other materials or loading conditions. This paper presents a numerical method for predicting bulk quantities of the spallation process, such as the average recession rate, for crystalline materials. The method is based on direct numerical simulations of the microstructure. The crystal grains and their boundaries are modeled with finite elements and cohesive zones. These elements have anisotropic and temperature-dependent physical properties, a novel level of fidelity and one that accurately captures known crystal phenomena including the alpha-beta quartz transition. These models of the crystalline material and the thermal spallation process are validated against experiment results for Barre granite, and then applied to predict the thermal spallation of Martian basalt.