scholarly journals Elastodynamic image forces on screw dislocations in the presence of phase boundaries

2017 ◽  
Vol 473 (2205) ◽  
pp. 20170484 ◽  
Author(s):  
Beñat Gurrutxaga-Lerma
Keyword(s):  
Screw Dislocation ◽  
Image Force ◽  
Planar Interface ◽  
Rigid Surface ◽  
Phase Boundaries ◽  
Unit Force ◽  
Screw Dislocations ◽  
Planar Phase ◽  
Explicit Formulae ◽  
Rigid Interface

The elastodynamic image forces acting on straight screw dislocations in the presence of planar phase boundaries are derived. Two separate dislocations are studied: (i) the injected, non-moving screw dislocation and (ii) the injected (or pre-existing), generally non-uniformly moving screw dislocation. The image forces are derived for both the case of a rigid surface and of a planar interface between two homogeneous, isotropic phases. The case of a rigid interface is shown to be solvable employing Head's image dislocation construction. The case of the elastodynamic image force due to an interface is solved by deriving the reflected wave's contribution to the global solution across the interface. This entails obtaining the fundamental solution (Green's function) for a point unit force via Cagniard's method, and then applying the convolution theorem for a screw dislocation modelled as a force distribution. Complete, explicit formulae are provided when available. It is shown that the elastodynamic image forces are generally affected by retardation effects, and that those acting on the moving dislocations display a dynamic magnification that exceed the attraction (or repulsion) predicted in classical elastostatic calculations.

A Piezoelectric Screw Dislocation Interacting with a Dielectric Crack in a Hexagonal Piezoelectric Material

2005 ◽  
Vol 9 ◽  
pp. 183-190
Author(s):  
Jin Xi Liu ◽  
X.L. Liu
Keyword(s):  
Electric Field ◽  
Screw Dislocation ◽  
Electric Displacement ◽  
Image Force ◽  
Mapping Method ◽  
Piezoelectric Medium ◽  
Intensity Factors ◽  
Potential Jump ◽  
Piezoelectric Screw Dislocation ◽  
Dielectric Crack

This paper is concerned with the interaction of a piezoelectric screw dislocation with a semi-infinite dielectric crack in a piezoelectric medium with hexagonal symmetry. The solution of the considered problem is obtained from the dislocation solution of a piezoelectric half-plane adjoining a gas medium of dielectric constant ε0 by using the conformal mapping method. The intensity factors of stress, electric displacement and electric field and the image force on the dislocation are given explicitly. The effect of electric boundary conditions on the dislocation-crack interaction is analyzed and discussed in detail. The results show that ε0 only influences the electric displacement and electric field intensity factors and the image force produced by the electric potential jump.

scholarly journals Screw dislocations in the X-cube fracton model

2021 ◽  
Vol 10 (4) ◽  
Author(s):  
Nandagopal Manoj ◽  
Kevin Slagle ◽  
Wilbur Shirley ◽  
Xie Chen
Keyword(s):  
Screw Dislocation ◽  
Layered Structure ◽  
Ground State ◽  
The Other ◽  
Screw Dislocations ◽  
Topological States ◽  
Ground State Degeneracy ◽  
Induced Motion ◽  
D Model

The X-cube model, a prototypical gapped fracton model, was shown in Ref. [1] to have a foliation structure. That is, inside the 3+1 D model, there are hidden layers of 2+1 D gapped topological states. A screw dislocation in a 3+1 D lattice can often reveal nontrivial features associated with a layered structure. In this paper, we study the X-cube model on lattices with screw dislocations. In particular, we find that a screw dislocation results in a finite change in the logarithm of the ground state degeneracy of the model. Part of the change can be traced back to the effect of screw dislocations in a simple stack of 2+1 D topological states, hence corroborating the foliation structure in the model. The other part of the change comes from the induced motion of fractons or sub-dimensional excitations along the dislocation, a feature absent in the stack of 2+1D layers.

Duffin–Kemmer–Petiau oscillator in the presence of a cosmic screw dislocation

2020 ◽  
Vol 35 (30) ◽  
pp. 2050195
Author(s):  
Soroush Zare ◽  
Hassan Hassanabadi ◽  
Marc de Montigny
Keyword(s):  
Elastic Medium ◽  
Screw Dislocation ◽  
Topological Defect ◽  
Potential Functions ◽  
Wave Functions ◽  
Screw Dislocations ◽  
Energy Eigenvalues ◽  
Heun Function ◽  
Uvarov Method ◽  
The Impact

We examine the behavior of spin-zero bosons in an elastic medium which possesses a screw dislocation, which is a type of topological defect. Therefore, we solve analytically the Duffin–Kemmer–Petiau (DKP) oscillator for bosons in the presence of a screw dislocation with two types of potential functions: Cornell and linear-plus-cubic potential functions. For each of these functions, we analyze the impact of screw dislocations by determining the wave functions and the energy eigenvalues with the help of the Nikiforov–Uvarov method and Heun function.

scholarly journals Interaction of a Screw Dislocation with Interface and Wedge-Shaped Cracks in One-Dimensional Hexagonal Piezoelectric Quasicrystals Bimaterial

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Lian he Li ◽  
Yue Zhao
Keyword(s):  
Screw Dislocation ◽  
Electric Fields ◽  
Electric Displacement ◽  
Image Force ◽  
Coupling Constants ◽  
Geometrical Parameters ◽  
Intensity Factors ◽  
One Dimensional ◽  
Special Cases ◽  
Analytical Expressions

Interaction of a screw dislocation with wedge-shaped cracks in one-dimensional hexagonal piezoelectric quasicrystals bimaterial is considered. The general solutions of the elastic and electric fields are derived by complex variable method. Then the analytical expressions for the phonon stresses, phason stresses, and electric displacements are given. The stresses and electric displacement intensity factors of the cracks are also calculated, as well as the force on dislocation. The effects of the coupling constants, the geometrical parameters of cracks, and the dislocation location on stresses intensity factors and image force are shown graphically. The distribution characteristics with regard to the phonon stresses, phason stresses, and electric displacements are discussed in detail. The solutions of several special cases are obtained as the results of the present conclusion.

scholarly journals Interaction of Screw Dislocation with Edge Interfacial Crack on Fine-Grained Piezoelectric Coating/Substrate

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Shuaishuai Hu ◽  
Jiansheng Liu ◽  
Junlin Li ◽  
Xiufeng Xie
Keyword(s):  
Screw Dislocation ◽  
Interfacial Crack ◽  
Mapping Function ◽  
Image Force ◽  
Infinite Plane ◽  
Principle Of Superposition ◽  
Fine Grained ◽  
Substrate Structure ◽  
Piezoelectric Bimaterial ◽  
The Right

The interaction between micro- and macrocracks in a fine-grained piezoelectric coating/substrate under remote antiplane mechanical and in-plane electrical loadings was studied. The principle of superposition and a mapping function method was used to transform the fine-grained coating/substrate structure containing the screw dislocation and the edge interfacial crack into the right semi-infinite plane piezoelectric bimaterial with screw dislocation to simplify the problem. Furthermore, the electric field, displacement field, intensity factors, and image force of these two problems were established. In addition, numerical calculations were then given graphically to study the effects of the elastic modulus of the material, the size of the crack, the thickness of the coating, and the screw dislocation angle on the edge interface crack and dislocation.

Atomic-Scale Modeling of the Annihilation of Jogged Screw Dislocation Dipoles

1999 ◽  
Vol 578 ◽  
Author(s):  
T. Vegge ◽  
O. B. Pedersen ◽  
T. Leffers ◽  
K. W. Jacobsen
Keyword(s):  
Molecular Dynamics ◽  
Screw Dislocation ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Elastic Band ◽  
Screw Dislocations ◽  
Scale Modeling ◽  
Band Method

AbstractUsing atomistic simulations we investigate the annihilation of screw dislocation dipoles in Cu. In particular we determine the influence of jogs on the annihilation barrier for screw dislocation dipoles. The simulations involve energy minimizations, molecular dynamics, and the Nudged Elastic Band method. We find that jogs on screw dislocations substantially reduce the annihilation barrier, hence leading to an increase in the minimum stable dipole height.

scholarly journals Confinement of Screw Dislocations to Predetermined Lateral Positions in (0001) 4H-SiC Epilayers Using Homoepitaxial Web Growth

2002 ◽  
Vol 742 ◽  
Author(s):  
Philip G. Neudeck ◽  
David J. Spry ◽  
Andrew J. Trunek ◽  
J. Anthony ◽  
Glenn M. Beheim
Keyword(s):  
Screw Dislocation ◽  
Potassium Hydroxide ◽  
Growth Process ◽  
Crystal Quality ◽  
Etch Pits ◽  
Screw Dislocations ◽  
Homoepitaxial Growth ◽  
Sic Wafer

ABSTRACTThis paper reports initial demonstration of a cantilevered homoepitaxial growth process that places screw dislocations at predetermined lateral positions in on-axis 4H-SiC mesa epilayers. Thin cantilevers were grown extending toward the interior of hollow pre-growth mesa shapes etched into an on-axis 4H-SiC wafer, eventually completely coalescing to form roofed cavities. Each completely coalesced cavity exhibited either: 1) a screw dislocation growth spiral located exactly where final cantilever coalescence occurred, or 2) no growth spiral. The fact that growth spirals are not observed at any other position except the central coalescence point suggests that substrate screw dislocations, initially surrounded by the hollow portion of the pre-growth mesa shape, are relocated to the final coalescence point of the webbed epilayer roof. Molten potassium hydroxide etch studies revealed that properly grown webbed cantilevers exhibited no etch pits, confirming the superior crystal quality of the cantilevers.

Atomistic Simulation of ½ Screw Dislocations in BCC Tungsten

2008 ◽  
Vol 59 ◽  
pp. 247-252 ◽  
Author(s):  
Jan Fikar ◽  
Robin Schäublin ◽  
Carolina Björkas
Keyword(s):  
Screw Dislocation ◽  
Atomistic Simulation ◽  
Bond Order ◽  
Analytical Approach ◽  
Atomistic Simulations ◽  
Screw Dislocations ◽  
Atom Model ◽  
Embedded Atom ◽  
Bond Order Potential

Atomistic simulations are used to describe the ½<111> screw dislocation in tungsten. Two different embedded atom model (EAM) potentials and one bond-order potential (BOP) are compared. A new analytical approach for constructing asymmetrical screw dislocations is presented.

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