Ph.D. Proposal Presentation by Vikas Tomar
Friday, April 2, 2004
(Dr. Min Zhou, advisor)
"Atomistic Modeling of Mechanical and Energetic Response of Fe2O3+Al Reactive Metal Powder Mixtures"
This research focuses on mechanical and energetic response of nanostructured reactive metal powder (NRMP) mixtures using atomistic modeling. The emphasis is on a characterization of the correlation between morphology and applied load that affects the constitutive behavior and energetic characteristics such as the initiation of chemical reactions and dissipation of energy under shock-loading. Fe2O3+Al thermite metal powder mixture is chosen as the model system. The atomistic modeling is carried out using classical molecular dynamics (MD). This requires an interatomic potential to describe the effective interaction between atoms with a description of various crystal systems that constitute the NRMP mixture. A variable charge cluster functional potential is developed for this purpose. Interatomic interactions in the potential are described using a cluster functional and a term describing electrostatic interactions among environment-dependent charges. A range of Al+Fe2O3 nanostructures with random and idealized morphology for a range of Al, Fe2O3, and void volume fractions are generated for the mechanical and energetic response analyses. Mechanical response analyses involve characterization of quasi-static deformation of the nanostructures to predict dependence of the elastic moduli on morphology and composition, and a characterization of the size-scale effects associated with this dependence. Equilibrium MD is proposed to be used to carry out simulations for this purpose. Energetic response analyses focus on a characterization of energy absorption charcteristics of the nanostructures as a function of morphology, composition, and shock-loading conditions, and an investigation of correlation between morphology and shock-loading conditions that lead to the initiation of chemical reactions. This is proposed to be carried out using uni-axial shock-wave propagation simulations based on non-equilibrium molecular dynamics. As part of an overall program on the design of multi-functional materials, this research is expected to yield insights for the design of energetic structural materials through nano-scale quantification and optimization.