Date of Award
Master of Science (MS)
Fused silica is a great ballistic ceramic glass material with a complex phase diagram. With its transparent finish, high stiffness, and high hardness, it is widely adopted as transparent impact-resistant structures (e.g. windshields, door windows, and viewports) in combat related applications. Under a shock impact, a significant amount of energy will be effectively absorbed due to the phase transition of fused silica to stishovite, thereby taking most of the destructive energy away. Therefore, it is important to understand the mechanism behind the phase transition between fused silica and stishovite in order to better adopt this material for energy absorption and protection materials for future combat protection applications.
This research adopts molecular dynamics (MD) simulations and the Multi-Scale Shock Technique (MSST) to investigate the shock impact of fused silica under three shock velocity conditions. A systematic parameterization and characterization of the empirical potential is performed. A 4×4×4 nm3 fused silica sample is prepared by a heating and cooling process to create a truly amorphous sample. The parameters required for the MSST are systemically benchmarked. The phase transition of fused silica under shock impact is then investigated. It is concluded that the size of the sample used in the shock experiments has a large impact on the parameter calibration in the MSST method and to the nucleation and formation of stishovite polycrystal structures under shock impact. Future work will be focusing on the development of MSST method to eliminate the parameter calibration and better predict the material behavior under shock impact.
Woods, Tristan, "Multi-Scale Molecular Dynamics Simulation of Fused Silica Under Shock Impact" (2020). All Theses. 3375.