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Chiqun Zhang's picture

On the relevance of generalized disclinations in defect mechanics

Chiqun Zhang            Amit Acharya

The utility of the notion of generalized disclinations in materials science is discussed within the physical context of modeling interfacial and bulk line defects like defected grain and phase boundaries, dislocations and disclinations. The Burgers vector of a disclination dipole in linear elasticity is derived, clearly demonstrating the equivalence of its stress field to that of an edge dislocation. We also prove that the inverse deformation/displacement jump of a defect line is independent of the cut-surface when its g.disclination strength vanishes. An explicit formula for the displacement jump of a single localized composite defect line in terms of given g.disclination and dislocation strengths is deduced based on the Weingarten theorem for g.disclination theory at finite deformation. The Burgers vector of a g.disclination dipole at finite deformation is also derived.

Review Article: Atomistic Aspects of Fracture

Any fracture process ultimately involves the rupture of atomic bonds. Processes at the atomic scale therefore critically influence the toughness and overall fracture behavior of materials. Atomistic simulation methods including large-scale molecular dynamics simulations with classical potentials, density functional theory calculations and advanced concurrent multiscale methods have led to new insights e.g.

Cai Wei's picture

Postdoctoral Position Opening at Stanford University

Prof. Wei Cai at the Mechanical Engineering Department of Stanford University is seeking a postdoctoral researcher to lead a project on the modeling of grain structure evolution in the surface layer under friction.  The major task of this project is the development of a phase field model for grain/sub-grain structure evolution under friction.  It is likely that molecular dynamics and dislocation dynamics simulations would be required as well to obtain a good physical understanding of the process.

Post-Doc/PhD in mechanics of grain boundaries at Max-Planck-Institut für Eisenforschung, Düsseldorf

MPI für Eisenforschung, Düsseldorf, Department for Microstructure Physics and Alloy Design
Post-Doc or PhD Position: Characterizing and modeling the mechanics of crystalline interfaces

Modeling grain boundaries using FEM (Abaqus)

Hi,

I would like to model a microstructure using Abaqus. My question is how to deal with the grain boundaries ? Should I use cohesive elements ? Any ideas on modeling grain boundaries using FEM will be very helpfull.

Thanks,

Ayoub

Teng Li's picture

Effects of grain boundary adhesion and grain size on ductility of thin metal films on polymer substrates

We study the effects of grain boundary adhesion and grain size on the ductility of thin metal films well bonded to polymer substrates, using finite element method. It is shown that the ductility of polymer-supported metal films increases approximately linearly as the grain boundary adhesion increases, and as the grain size decreases. A rule-of-thumb estimate of the ductility of polymer-supported metal films agrees well with the simulation results.

In press, Scripta Materialia, 2008 

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