Glass additive manufacturing is an emerging technology for the printing of complex glass structures. In one such system, a glass filament is fed onto a glass slide and heated by a laser to working temperatures. We present a 3D heat transfer model of this glass AM system (GLAMS), using the open source multi-physics modeling program Truchas. This model relies on a mimetic finite difference discretization of the heat conduction equation on static unstructured meshes. The effects of laser heat flux, thermal radiation, convection, and changing thermal contact in the system are incorporated via boundary conditions and internal interface conditions. Such modeling gives us insight into behavior that is difficult or impossible to measure in the laboratory, such as temperatures and thermal gradients interior to the glass. Results are shown for thermal gradients, heatup and cooldown times, steady-state temperatures, and a sensitivity analysis of the process. We analyze the melt region at steady-state, showing the dominant mode of heat transfer is thermal conductivity, while radiation and convection are relatively insignificant. The time needed to reach steady state under laser heating is found to scale linearly with laser power and spot size within the processing range. Results are also compared against experimental thermal camera readings of prints with soda lime and borosilicate glasses.

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