Molecular plasticity of polymeric glasses in the elastic regime

Papakonstantopoulos, George J.; Riggleman, Robert A.; Barrat, Jean‐Louis; Pablo, Juan J. de

doi:10.1103/physreve.77.041502

Cited by 79 publications

(86 citation statements)

References 33 publications

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“…Similar observations were made for the simulation of deformation of polymer chains [20]. The plastic deformation event is strongly localized, and consists of one atomic bond being broken, while a new bond in a perpendicular direction is formed in close vicinity, resulting in bond exchange, or reorientation.…”

Section: Local Plastic Deformationsupporting

confidence: 52%

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Mechanical Properties of Metallic Glasses

Egami

Iwashita

Dmowski

2013

Metals

134

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Metallic glasses are known for their outstanding mechanical strength. However, the microscopic mechanism of failure in metallic glasses is not well-understood. In this article we discuss elastic, anelastic and plastic behaviors of metallic glasses from the atomistic point of view, based upon recent results by simulations and experiments. Strong structural disorder affects all properties of metallic glasses, but the effects are more profound and intricate for the mechanical properties. In particular we suggest that mechanical failure is an intrinsic behavior of metallic glasses, a consequence of stress-induced glass transition, unlike crystalline solids which fail through the motion of extrinsic lattice defects such as dislocations.

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Section: Local Plastic Deformationsupporting

confidence: 52%

“…rather than Equation (20). So the stress affects the activation energy not through the activation volume but through the elastic self-energy.…”

Section: Equivalence Of Stress and Temperaturementioning

confidence: 99%

Mechanical Properties of Metallic Glasses

Egami

Iwashita

Dmowski

2013

Metals

134

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“…At such scales, a typical glassy sample can be described as consisting of coexisting ''hard'' and ''soft'' regions. This behavior is independent of the precise method which is used to define the coarse grained elastic constant, which may involve either the use of statistical mechanical formulas at a local scale, [13,14] or exploiting the linear relationship between coarse grained stress and strain field. [15] Here, we present results for the local bulk modulus obtained from a third approach, originally introduced by Sollich and Barra, [31] which has the advantage of being easily implemented at a reduced computational cost.…”

Section: Local Mechanical Propertiesmentioning

confidence: 99%

“…[14,15] Here, the relevant events involve a local dilatation of the material which eventually gives rise to a cavity, and points to the local bulk modulus as a possible predictor.…”

Section: Local Mechanical Propertiesmentioning

confidence: 99%

Predictors of Cavitation in Glassy Polymers under Tensile Strain: A Coarse‐Grained Molecular Dynamics Investigation

Makke

Perez

Rottler

et al. 2011

Macro Theory & Simulations

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The nucleation of cavities in a homogenous polymer under tensile strain is investigated in a coarse-grained molecular dynamics simulation. In order to establish a causal relation between local microstructure and the onset of cavitation, a detailed analysis of some local properties is presented. In contrast to common assumptions, the nucleation of a cavity is neither correlated to a local loss of density nor, to the stress at the atomic scale and nor to the chain ends density in the undeformed state. Instead, a cavity in glassy polymers nucleates in regions that display a low bulk elastic modulus. This criterion allows one to predict the cavity position before the cavitation occurs. Even if the localization of a cavity is not directly predictable from the initial configuration, the elastically weak zones identified in the initial state emerge as favorite spots for cavity formation.

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“…From this figure, we appreciate a very dramatic drop of the flow speed in the initial stage of the evolution, corresponding to a very substantial enhancement of the fluid viscosity (about four orders). The system remains in this 'arrested' state for a very long time, over three millions timesteps, until it suddenly starts to regain its initial velocity through a bumpy dynamics, characterized by a series of sudden jumps [10]. These viscosity jumps signal 'plastic events', whereby the system manages to break the density locks (cages) which blocked the flow in the initial phase.…”

Section: Pacs Numbersmentioning

confidence: 99%

Mesoscopic Lattice Boltzmann Modeling of Flowing Soft Systems

2009

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A mesoscopic multi-component lattice Boltzmann model with short-range repulsion between different species and short/mid-ranged attractive/repulsive interactions between like-molecules is introduced. The interplay between these composite interactions gives rise to a rich configurational dynamics of the density field, exhibiting many features of disordered liquid dispersions (microemulsions) and soft-glassy materials, such as long-time relaxation due to caging effects, anomalous enhanced viscosity, ageing effects under moderate shear and flow above a critical shear rate. PACS numbers:The rheology of flowing soft systems, such as emulsions, foams, gels, slurries, colloidal glasses and related fluids, is a fast-growing sector of modern non-equilibrium thermodynamics, with many applications in material science,chemistry and biology [1].These materials exhibit a number of distinctive features, such as long-time relaxation, anomalous viscosity, aging behaviour, whose quantitative description is likely to require profound extensions of non-equilibrium statistical mechanics. The study of these phenomena sets a pressing challenge for computer simulation as well, since characteristic time-lenghts of disordered fluids can escalade tens of decades over the molecular time scales. To date, the most credited techniques for computational studies of these complex flowing materials are Molecular Dynamics and Monte Carlo simulations [2]. Molecular dynamics in principle provides a fully ab-initio description of the system, but it is limited to space-time scales significantly shorter than experimental ones. Monte Carlo methods are less affected by these limitations, but they are bound to deal with equilibrium states. As a result, neither MD nor MC can easily take into account the non-equilibrium dynamics of complex flowing materials, such as micro-emulsions, on space-time scales of hydrodynamic interest. In the last decade, a new class of mesoscopic methods, based on minimal lattice formulations of Boltzmann's kinetic equation, have captured significant interest as an efficient alternative to continuum methods based on the discretization of the Navier-Stokes equations for non-ideal fluids [3]. To date, a very popular such mesoscopic technique is the socalled pseudo-potential-Lattice-Boltzmann (LB) method, developed over a decade ago by Shan and Chen (SC) [4]. In the SC method, potential energy interactions are represented through a density-dependent mean-field pseudopotential, Ψ[ρ], and phase separation is achieved by imposing a short-range attraction between the light and dense phases. In this Letter, we provide the first numerical evidence that a suitably extended, two-species, mesoscopic lattice Boltzmann model is capable of reproducing many features of soft-glassy (micro-emulsions), such as structural arrest, anomalous viscosity, cage-effects and ageing under shear. The key feature of our model is the where f is is the probability of finding a particle of species s at site r and time t, moving along the ith lattice direction defi...

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Molecular plasticity of polymeric glasses in the elastic regime

Cited by 79 publications

References 33 publications

Mechanical Properties of Metallic Glasses

Mechanical Properties of Metallic Glasses

Predictors of Cavitation in Glassy Polymers under Tensile Strain: A Coarse‐Grained Molecular Dynamics Investigation

Mesoscopic Lattice Boltzmann Modeling of Flowing Soft Systems

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