Multiphysics FEA Simulation of Residual Strain and Stress Limits in Laminated Glass for Lunar Environments

The development of specialized windows for lunar habitats is a complex challenge due to the Moon's harsh thermal environment. These windows must effectively shield against neutron radiation and withstand the impact of micrometeorites in extreme temperature variations. There is a significant difference in the coefficients of thermal expansion (CTE) between the neutron shielding layer made of carbon-doped hexagonal boron nitride (hBN) and the bulletproof layer made of spinel. This difference causes substantial residual strain, which can compromise the structural integrity of the windows. This research deals with COMSOL Multiphysics simulations (finite element analysis (FEA) software) to explore potential solutions to these issues on a macroscopic scale. The analysis of these strains is challenging due to the complex structural-thermal-optical coupling effects. Several conditions must be considered. For example, the glass must maintain a transparency of at least 60% within the visible light spectrum. Therefore, the adhesive layer between the two interfaces must be thin and transparent. Additionally, we must consider the vacuum environment, weak gravity (about 1/6th of Earth's), and the extreme temperature conditions. Various adhesive materials were tested to find those most effective at mitigating residual strain between the perovskite (hBN) and spinel layers under these conditions. The study also examined the effect of different surface orientations on the deformation of the composite glass structure. Furthermore, the simulations measured the elastic limits of the laminated glass when subjected to micrometeorite impacts, considering their velocity and impact vaporization flux. The results of the simulations indicated that fiber-reinforced adhesives are particularly effective at reducing residual strain. Optimal surface orientations that minimize deformation were also identified. Additionally, the study found that using multiple neutron shielding layers could enhance the structural durability of the windows while maintaining the necessary transparency (minimum 60% transmittance at 600 nm), which is crucial for visibility in lunar habitats. The study also includes calculating the maximum elastic limits through nonlinear elastic deformation simulations of laminated glass subjected to asteroid impacts and proposing the optimal layering structure and materials for the laminated glass's bulletproof layer. This study makes significant contributions to the field of materials science and engineering for space exploration. The findings provide practical insights into the development of durable and transparent glass windows for lunar bases, addressing both protective and functional requirements. The proposed materials and structural configurations are expected to improve the safety and efficacy of lunar habitats, supporting the advancement of human presence on the Moon.