Modeling and Characterization of the Elastic Behavior of Interfaces in Nanostructured Materials: From an Atomistic Description to a Continuum Approach

Interface theory;Atomistic calculations;Nanoscale materials;Grain boundaries;Continuum mechanics

Dingreville, Remi ; Mechanical Engineering

University:Georgia Institute of Technology

Department:Mechanical Engineering

关键词: Interface theory;    Atomistic calculations;    Nanoscale materials;    Grain boundaries;    Continuum mechanics;   

Others  :  https://smartech.gatech.edu/bitstream/1853/19776/1/dingreville_remi_200712_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

In this dissertation, an innovative approach combining continuum mechanics and atomistic simulations is exposed to develop a nanomechanics theory for modeling and predicting the macroscopic behavior of nanomaterials. This nanomechanics theory exhibits the simplicity of the continuum formulation while taking into account the discrete atomic structure and interaction near surfaces/interfaces. There are four primary objectives to this dissertation. First, theory of interfaces is revisited to better understand its behavior and effects on the overall behavior of nanostructures. Second, atomistic tools are provided in order to efficiently determine the properties of free surfaces and interfaces. Interface properties are reported in this work, with comparison to both theoretical and experimental characterizations of interfaces. Specifically, we report surface elastic properties of groups 10 11 transition metals as well as properties for low-CSL grain boundaries in copper. Third, we propose a continuum framework that casts the atomic level information into continuum quantities that can be used to analyze, model and simulate macroscopic behavior of nanostructured materials. In particular, westudy the effects of surface free energy on the effective modulus of nano-particles, nanowiresand nano-films as well as nanostructured crystalline materials and propose a general framework valid for any shape of nanostructural elements / nano-inclusions (integral forms) that characterizes the size-dependency of the elastic properties. This approach bridges the gap between discrete systems (atomic level interactions) and continuum mechanics. Finally this continuum outline is used to understand the effects of surfaces on the overall behavior of nano-size structural elements (particles, films, fibers, etc.) and nanostructured materials. More specifically we will discuss the impact of surface relaxation, surface elasticity and non-linearity of the underlying bulk on the properties nanostructured materials.