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Event Scheduled for Oct 30, 2017

Event: MSE PhD Dissertation Proposal - Garvit Agarwal

Location: IMS-159

Time: 10:00 am

Details of Event:
PhD Dissertation Proposal

Presenter: Garvit Agarwal

Major Advisor: Dr. Avinash M. Dongare
Associate Advisors: Dr. Rampi Ramprasad, Dr. Mark Aindow, Dr. Seok-Woo Lee and Dr. Ying Li

Date: Monday, October 30, 2017

Time: 10:00 AM

Room: IMS-159

Title: Mesoscale Modeling of Defect and Damage Evolution in Lightweight Metallic Materials under Shock Loading Conditions

Abstract:
The capability to predict the impact tolerance of the next generation lightweight metallic materials for protective armor application requires a fundamental understanding of the deformation and failure behavior of these materials under dynamic loading (impact/shock) conditions. Loading conditions of impact/shock result in complex stress states that range from uniaxial compression to uniaxial tension at very high strain rates ranging from 105 s-1 to 1010s-1. The deformation response of these materials is determined by the capability of the metallic microstructure to nucleate dislocations during shock compression and the failure response is determined by the creation of weak sites for nucleation of voids during triaxial expansion. A critical challenge in the understanding of the mechanisms of plastic deformation and onset of dynamic failure (spallation) is the short time scales associated with these phenomena that limit the capabilities of experimental characterization methods to investigate these mechanisms. This dissertation demonstrates the capability of the quasi-coarse-grained dynamics (QCGD) to scale up the predictive capability of classical molecular dynamics simulations to the mesoscales and, at the same time, retain the atomic scale characteristics of the deformation processes involved. The QCGD method is based on coarse-graining the atomic-scale microstructure using a reduced number of representative atoms (R-atoms) and scaling relationships for interatomic potentials to retain the atomic scale energetics of R-atoms at the mesoscales.

Five objectives are proposed to investigate the micromechanisms for the evolution, interaction, and accumulation of defects (dislocations, twins, interfaces) and damage (voids) in lightweight metallic materials at the atomic scales using classical molecular dynamics (MD) simulations and at the mesoscales using quasi-coarse-grained dynamics (QCGD) simulations. These objectives focus on single crystal and polycrystalline Al microstructures as model FCC systems and the interactions between the Al atoms/R-atoms are defined using the embedded atom method (EAM) interatomic potential. The QCGD predicted strain rate dependence of the spall strength for these microstructures is in excellent agreement with that computed experimentally. The capability of the QCGD simulations, the scaling relationships for the various levels of coarsening and the proposed research objectives are discussed.

Target Audience: Not Available

Sponsored By: Materials Science and Engineering Department

Pamphlet/Flyer: No Pamphlet/Flyer Available


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