January 21, 2022
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Ablative TPS that burn up during entry provide additional protection over reusable TPS like that used for the space shuttle. These materials are composed of carbon fibers impregnated with a phenolic resin and their protection results from thermal transport and endothermic chemical reactions. It is important to improve our understanding of the mechanisms that govern the performance of ablative TPS so we can ensure safety while still minimizing weight. In this work, we applied atomistic and mesoscale modeling to investigate the mechanisms. An approach was developed to generate realistic carbon fiber and char structures, and then molecular dynamics simulations were used to simulate the destruction of these structures due to carbon oxidation to form CO and other gases. The information from the atomistic scale was then used to develop mesoscale models of the pyrolysis of the resin to form char, the oxidation of the char, and the eventual oxidation of the fibers. These models represent the heat transport and are coupled to phase field method models of the chemical processes. They are implemented in the Macaw application that uses the open source Multiphysics Object Oriented Simulation Environment.
Dr. Michael Tonks is a Professor of Materials Science and Engineering and Nuclear Engineering and the Department of Materials Science and Engineering Alumni Professor at the University of Florida (UF). Previous to his current appointments, he was an Associate Professor at UF for three years, Assistant Professor of Nuclear Engineering at Pennsylvania State University for two years, and a staff scientist in the Fuels Modeling and Simulation Department at Idaho National Laboratory for six years. Prof. Tonks was the original creator and is a developer of the phase field module in the open source Multiphysics Object-Oriented Simulation Environment (MOOSE), which is widely used across the world. He also helped to pioneer the approach taken in the DOE Nuclear Energy Advanced Modeling and Simulation (NEAMS) program to use multiscale modeling and simulation to inform the development of materials models for nuclear materials, and he won the NEAMS Excellence Award for that work in 2014. He also won the Presidential Early Career Award for Scientists and Engineers in 2017 and the TMS Brimacombe Medal in 2022. His research is focused on using mesoscale modeling and simulation results coupled with experimental data to investigate the co-evolution of microstructure and properties in materials in harsh environments.