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Full-Text Articles in Engineering
Accelerated Relaxation In Disordered Solids Under Cyclic Loading With Alternating Shear Orientation, Nikolai V. Priezjev
Accelerated Relaxation In Disordered Solids Under Cyclic Loading With Alternating Shear Orientation, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The effect of alternating shear orientation during cyclic loading on the relaxation dynamics in disordered solids is examined using molecular dynamics simulations. The model glass was initially prepared by rapid cooling from the liquid state and then subjected to cyclic shear along a single plane or periodically alternated in two or three dimensions. We showed that with increasing strain amplitude in the elastic range, the system is relocated to deeper energy minima. Remarkably, it was found that each additional alternation of the shear orientation in the deformation protocol brings the glass to lower energy states. The results of mechanical tests …
Aging And Rejuvenation During Elastostatic Loading Of Amorphous Alloys, Nikolai V. Priezjev
Aging And Rejuvenation During Elastostatic Loading Of Amorphous Alloys, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
Using molecular dynamics simulations, we investigate the effect of uniaxial elastostatic compression on the potential energy, structural relaxation, and mechanical properties of binary glasses. We consider the three-dimensional Kob-Andersen binary mixture, which was initially cooled from the liquid state to the glass phase with a slow rate at zero pressure. The glass was then loaded with a static stress at the annealing temperature during extended time intervals. It is found that the static stress below the yielding point induces large-scale plastic deformation and significant rejuvenation when the annealing temperature is smaller than a fraction of the glass transition temperature. By …
Atomistic Modeling Of Heat Treatment Processes For Tuning The Mechanical Properties Of Disordered Solids, Nikolai V. Priezjev
Atomistic Modeling Of Heat Treatment Processes For Tuning The Mechanical Properties Of Disordered Solids, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
We investigate the effect of a single heat treatment cycle on the potential energy states and mechanical properties of metallic glasses using molecular dynamics simulations. We consider the three-dimensional binary mixture, which was initially cooled with a computationally slow rate from the liquid state to the solid phase at a temperature well below the glass transition. It was found that a cycle of heating and cooling can relocate the glass to either rejuvenated or relaxed states, depending on the maximum temperature and the loading period. Thus, the lowest potential energy is attained after a cycle with the maximum temperature slightly …
The Potential Energy States And Mechanical Properties Of Thermally Cycled Binary Glasses, Nikolai V. Priezjev
The Potential Energy States And Mechanical Properties Of Thermally Cycled Binary Glasses, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The influence of repeated thermal cycling on mechanical properties, structural relaxation, and evolution of the potential energy in binary glasses is investigated using molecular dynamics simulations. We consider a binary mixture with strongly non-additive cross interactions, which is annealed across the glass transition with different cooling rates and then exposed to one thousand thermal cycles at constant pressure. We found that during the first few hundred transient cycles, the potential energy minima after each cycle gradually decrease and the structural relaxation proceeds via collective, irreversible displacements of atoms. With increasing cycle number, the amplitudes of the volume and potential energy …
The Influence Of Complex Thermal Treatment On Mechanical Properties Of Amorphous Materials, Nikolai V. Priezjev, Qing-Long Liu
The Influence Of Complex Thermal Treatment On Mechanical Properties Of Amorphous Materials, Nikolai V. Priezjev, Qing-Long Liu
Mechanical and Materials Engineering Faculty Publications
We study the effect of periodic, spatially uniform temperature variation on mechanical properties and structural relaxation of amorphous alloys using molecular dynamics simulations. The disordered material is modeled via a non-additive binary mixture, which is annealed from the liquid to the glassy state with various cooling rates and then either aged at constant temperature or subjected to thermal treatment. We found that in comparison to aged samples, thermal cycling with respect to a reference temperature of approximately half the glass transition temperature leads to more relaxed states with lower levels of potential energy. The largest energy decrease was observed for …
The Influence Of Periodic Shear On Structural Relaxation And Pore Redistribution In Binary Glasses, Nikolai V. Priezjev, Maxim A. Makeev
The Influence Of Periodic Shear On Structural Relaxation And Pore Redistribution In Binary Glasses, Nikolai V. Priezjev, Maxim A. Makeev
Mechanical and Materials Engineering Faculty Publications
The evolution of porous structure, potential energy and local density in binary glasses under oscillatory shear deformation is investigated using molecular dynamics simulations. The porous glasses were initially prepared via a rapid thermal quench from the liquid state across the glass transition and allowed to phase separate and solidify at constant volume, thus producing an extended porous network in an amorphous solid. We find that under periodic shear, the potential energy decreases over consecutive cycles due to gradual rearrangement of the glassy material, and the minimum of the potential energy after thousands of shear cycles is lower at larger strain …
The Effect Of Cryogenic Thermal Cycling On Aging, Rejuvenation, And Mechanical Properties Of Metallic Glasses, Nikolai V. Priezjev
The Effect Of Cryogenic Thermal Cycling On Aging, Rejuvenation, And Mechanical Properties Of Metallic Glasses, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The structural relaxation, potential energy states, and mechanical properties of a model glass subjected to thermal cycling are investigated using molecular dynamics simulations. We study a non-additive binary mixture which is annealed with different cooling rates from the liquid phase to a low temperature well below the glass transition. The thermal treatment is applied by repeatedly heating and cooling the system at constant pressure, thus temporarily inducing internal stresses upon thermal expansion. We find that poorly annealed glasses are relocated to progressively lower levels of potential energy over consecutive cycles, whereas well annealed glasses can be rejuvenated at sufficiently large …
Structural Transformations During Periodic Deformation Of Low-Porosity Amorphous Materials, Nikolai V. Priezjev, Maxim A. Makeev
Structural Transformations During Periodic Deformation Of Low-Porosity Amorphous Materials, Nikolai V. Priezjev, Maxim A. Makeev
Mechanical and Materials Engineering Faculty Publications
Atomistic simulations are employed to study structural evolution of pore ensembles in binary glasses under periodic shear deformation with varied amplitude. The consideration is given to porous systems in the limit of low porosity. The initial ensembles of pores are comprised of multiple pores with small sizes, which are approximately normally distributed. As periodic loading proceeds, the ensembles evolve into configurations with a few large-scale pores and significantly reduced number of small pores. These structural changes are reflected in the skewed shapes of the pore-size distribution functions and the appearance of a distinct peak at large length scales after hundreds …
Structural Relaxation Of Porous Glasses Due To Internal Stresses And Deformation Under Tensile Loading At Constant Pressure, Nikolai V. Priezjev, Maxim A. Makeev
Structural Relaxation Of Porous Glasses Due To Internal Stresses And Deformation Under Tensile Loading At Constant Pressure, Nikolai V. Priezjev, Maxim A. Makeev
Mechanical and Materials Engineering Faculty Publications
The time evolution of the pore size distributions and mechanical properties of amorphous solids at constant pressure is studied using molecular dynamics simulations. The porous glasses were initially prepared at constant volume conditions via a rapid thermal quench from the liquid state to the glassy region and allowing for simultaneous phase separation and material solidification. We found that at constant pressure and low temperature, the porous network becomes more compact and the glassy systems relocate to progressively lower levels of the potential energy. Although the elastic modulus and the average glass density both increase with the waiting time, their dependence …
Spatiotemporal Analysis Of Nonaffine Displacements In Disorderedsolids Sheared Across The Yielding Point, Nikolai V. Priezjev
Spatiotemporal Analysis Of Nonaffine Displacements In Disorderedsolids Sheared Across The Yielding Point, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The time evolution and spatial correlations of nonaffine displacements in deformed amorphous solids are investigated using molecular dynamics simulations. The three-dimensional model glass is represented via the binary mixture, which is slowly annealed well below the glass transition temperature and then sheared at a constant strain rate. It is shown that with increasing strain,the typical size of clusters of atoms with large nonaffine displacements increases, and these clusters remain spatially homogeneously distributed, until the yielding point when mobile atoms become localized within a system-spanning shear band. Furthermore, the yielding transition is associated with an abrupt change in the spatial correlation …
Shear Band Formation In Amorphous Materials Under Oscillatoryshear Deformation, Nikolai V. Priezjev
Shear Band Formation In Amorphous Materials Under Oscillatoryshear Deformation, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The effect of periodic shear on strain localization in disordered solids is investigated using molecular dynamics simulations. We consider a binary mixture of one million atoms annealed to a low temperature with different cooling rates and then subjected to oscillatory shear deformation with a strain amplitude slightly above the critical value. It is found that the yielding transition occurs during one cycle but the accumulation of irreversible displacements and initiation of the shear band proceed over larger number of cycles for more slowly annealed glasses. The spatial distribution and correlation function of nonaffine displacements reveal that their collective dynamics changes …