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Full-Text Articles in Engineering

Computational Studies Of Thermal Properties And Desalination Performance Of Low-Dimensional Materials, Yang Hong Aug 2019

Computational Studies Of Thermal Properties And Desalination Performance Of Low-Dimensional Materials, Yang Hong

Student Research Projects, Dissertations, and Theses - Chemistry Department

During the last 30 years, microelectronic devices have been continuously designed and developed with smaller size and yet more functionalities. Today, hundreds of millions of transistors and complementary metal-oxide-semiconductor cells can be designed and integrated on a single microchip through 3D packaging and chip stacking technology. A large amount of heat will be generated in a limited space during the operation of microchips. Moreover, there is a high possibility of hot spots due to non-uniform integrated circuit design patterns as some core parts of a microchip work harder than other memory parts. This issue becomes acute as stacked microchips get ...


Interactions Between Dislocations And Three-Dimensional Annealing Twins In Face Centered Cubic Metals, Yanxiang Liang, Xiaofang Yang, Mingyu Gong, Guisen Liu, Qing Liu, Jian Wang Mar 2019

Interactions Between Dislocations And Three-Dimensional Annealing Twins In Face Centered Cubic Metals, Yanxiang Liang, Xiaofang Yang, Mingyu Gong, Guisen Liu, Qing Liu, Jian Wang

Mechanical & Materials Engineering Faculty Publications

Annealing twins often form in metals with a face centered cubic structure during thermal and mechanical processing. Here, we conducted molecular dynamic (MD) simulations for copper and aluminum to study the interaction processes between {1 1 1}1/2 <1 1 0> dislocations and a three-dimensional annealing twin. Twin boundaries are characterized with Σ3{1 1 1} coherent twin boundaries (CTBs) and Σ3{1 1 2} incoherent twin boundaries (ITBs). MD results revealed that dislocation-ITB interactions affect slip transmission for a dislocation crossing CTBs, facilitating the nucleation of Lomer dislocation.


Molecular Dynamics Modeling And Simulation Of Bitumen Chemical Aging, Farshad Fallah Jul 2017

Molecular Dynamics Modeling And Simulation Of Bitumen Chemical Aging, Farshad Fallah

Civil Engineering Theses, Dissertations, and Student Research

Chemical aging of asphalt binder leads to significant changes in its mechanical and rheological properties, resulting in poor pavement behavior and distress. Various laboratory methods have been used to simulate asphalt aging during the service life of the pavement. However, controversy exists regarding the capability of these methods to predict field aging, as various factors interact with the pavement during service and the mechanism behind aging is not fully understood. The two main outcomes of chemical aging are oxidation of asphalt molecules, and change in asphalt SARA (saturate, aromatic, resin, and asphaltene) fractions. Reaction of oxygen with asphalt components forms ...


Extracting Continuum-Like Deformation And Stress From Molecular Dynamics Simulations, Lili Zhang, John Jasa, George Gazonas, Antoine Jerusalem, Mehrdad Negahban Jan 2014

Extracting Continuum-Like Deformation And Stress From Molecular Dynamics Simulations, Lili Zhang, John Jasa, George Gazonas, Antoine Jerusalem, Mehrdad Negahban

Mechanical & Materials Engineering Faculty Publications

We present methods that use results from molecular dynamics (MD) simulations to construct continuum parameters, such as deformation gradient and Cauchy stress, from all or any part of an MD system. These parameters are based on the idea of minimizing the difference between MD measures for deformation and traction and their continuum counterparts. The procedures should be applicable to non-equilibrium and inhomogeneous systems, and to any part of a system, such as a polymer chain. The resulting procedures provide methods to obtain first and higher order deformation gradients associated with any subset of the MD system, and associated expressions for ...