CAREER: Theory and Simulation of the Structure and Mechanical Properties of Non-crystalline Solids

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

This is a CAREER grant that combines research and education activities. The focus is on the theory and simulation of properties associated with non-crystalline solids. Non-crystalline solids exist as metals, ceramics, semiconductors and polymers, and find wide application in industry. Yet the atomic-level mechanisms that control the mechanical properties of non-crystals are poorly understood compared to the understanding of these mechanisms in crystals. The research on this grant will address fundamental questions regarding the atomic level microstructure of non-crystals as they relate to measurable mechanical properties. This will be accomplished by implementing large-scale parallel computer simulation methods to simulate the atomic level response of non-network forming glasses to applied stresses. The data from these simulations will be analyzed using a variety of correlation functions - some inspired by recent investigations in supercooled liquids and experimental fluctuation microscopy studies. Once analyzed, the data from the simulations will provide the foundation for a theory of non-crystalline plastic deformation based on well characterized atomic level processes. This theory will then be implemented numerically and continuum simulations will be directly compared to atomistic results to test the predictions of the theory. A greatly increased understanding of deformation and failure in non-crystalline materials will result from this investigation. In addition, this research will validate diagnostics for the microscopic characterization of these materials. This research project is timely because significant recent advances in four areas of research each have bearing on such an investigation. (1) Focusing on non-network forming glasses will allow this research to directly address issues critical to the development of an emerging new material, bulk metallic glass. (2) These investigations will build on recent advances using molecular dynamics simulation techniques to develop an understanding of plastic deformation in glasses below the glass transition temperature. (3) By focusing on non-network forming glasses this research will be able to directly link current research regarding the nature of the glass transition to the consequences of the details of this transition for the structure and properties of the glassy solid state. (4) The information gained about the relationship between medium-range order and non-crystalline deformation in non-network forming glasses will also help extend the applicability of fluctuation microscopy techniques to the characterization of these galsses in ways relevant to predicting their mechanical properties. This computational and theoretical research program will be integrated with an educational prgram at the University of Michigan that addresses the need to fully integrate computational and mathematical methods into the Materials Science and Engineering core curriculum. Introduction of these techniques on the undergraduate level will be accomplished in stages starting with a thorough redesign of the undergraduate "Kinetics and Transport" class and continuing with other core classes. The PI has taught, and is continuing to develop, a course on the graduate level covering computational materials science methods for molecular simulation. This course will also serve as an educational forum fo rteaching simulation methods developed and utilized in the research program. In addition to addressing educational issues through the university curriculum, this CAREER program also includes a targeted outreach effort to local community college students. This effort will address the motovational issues of under-represented minority students in introductory science classes at Washtenaw Community College. The goal of this effort is both to increase the rate at which these students transfer to the University of Michigan to pursue engineering as a career and to lay the groundwork for increased success amongst these students post-transfer. %%% This is a CAREER grant that combines research and education activities. The focus is on the theory and simulation of properties associated with non-crystalline solids. Non-crystalline solids exist as metals, ceramics, semiconductors and polymers, and find wide application in industry. Yet the atomic-level mechanisms that control the mechanical properties of non-crystals are poorly understood compared to the understanding of these mechanisms in crystals. The research on this grant will address fundamental questions regarding the atomic level microstructure of non-crystals as they relate to measurable mechanical properties. This will be accomplished by implementing large-scale parallel computer simulation methods to simulate the atomic level response of non-network forming glasses to applied stresses. The data from these simulations will be analyzed using a variety of correlation functions - some inspired by recent investigations in supercooled liquids and experimental fluctuation microscopy studies. Once analyzed, the data from the simulations will provide the foundation for a theory of non-crystalline plastic deformation based on well characterized atomic level processes. This theory will then be implemented numerically and continuum simulations will be directly compared to atomistic results to test the predictions of the theory. A greatly increased understanding of deformation and failure in non-crystalline materials will result from this investigation. In addition, this research will validate diagnostics for the microscopic characterization of these materials. This computational and theoretical research program will be integrated with an educational prgram at the University of Michigan that addresses the need to fully integrate computational and mathematical methods into the Materials Science and Engineering core curriculum. Introduction of these techniques on the undergraduate level will be accomplished in stages starting with a thorough redesign of the undergraduate "Kinetics and Transport" class and continuing with other core classes. The PI has taught, and is continuing to develop, a course on the graduate level covering computational materials science methods for molecular simulation. This course will also serve as an educational forum fo rteaching simulation methods developed and utilized in the research program. In addition to addressing educational issues through the university curriculum, this CAREER program also includes a targeted outreach effort to local community college students. This effort will address the motovational issues of under-represented minority students in introductory science classes at Washtenaw Community College. The goal of this effort is both to increase the rate at which these students transfer to the University of Michigan to pursue engineering as a career and to lay the groundwork for increased success amongst these students post-transfer.