نتایج جستجو برای: screw dislocation
تعداد نتایج: 43687 فیلتر نتایج به سال:
background appropriate treatment of acromioclavicular joint dislocation is controversial. acroplate fixation is one of the most common treatment methods of acromioclavicular joint (acj) dislocation. based on the risk of re-dislocation after acroplate fixation, we assumed that combined fixation with an acroplate and a coracoclavicular screw helps improve the outcome. objectives the main purpose ...
A (microscopic) static elastoplastic field theory of dislocations with moment and force stresses is considered. The relationship between the moment stress and the Nye tensor is used for the dislocation Lagrangian. We discuss the stress field of an infinitely long screw dislocation in a cylinder, a dipole of screw dislocations and a coaxial screw dislocation in a finite cylinder. The stress fiel...
Employing the empirical embedded-atom method potentials, the evolution of edge and screw dislocation core structure is calculated at different hydrogen concentrations. With hydrogen, the core energy and Peierls potential are reduced for all dislocations. A broaden-core and a quasi-split core structure are observed for edge and screw dislocation respectively. The screw dislocation and hydrogen i...
Screw dislocations play an important role in materials' mechanical, electrical and optical properties. However, imaging the atomic displacements in screw dislocations remains challenging. Although advanced electron microscopy techniques have allowed atomic-scale characterization of edge dislocations from the conventional end-on view, for screw dislocations, the atoms are predominantly displaced...
In this paper we present the equations of motion of a moving screw dislocation in the framework of the translation gauge theory of dislocations. In the gauge field theoretical formulation, a dislocation is a massive gauge field. We calculate the gauge field theoretical solutions of a uniformly moving screw dislocation. We give the subsonic and supersonic solutions. Thus, supersonic dislocations...
BACKGROUND Prosthetic reconstruction of hips with Crowe type-IV developmental dysplasia (a high complete dislocation) is technically demanding. Insufficient osseous coverage and osteopenic bone stock frequently necessitate transacetabular screw fixation to augment primary stability of the metal acetabular shell. We sought to determine whether a previously reported quadrant system for screw fixa...
Dislocation bias factors in bcc Fe have been calculated based on atomistic interaction energy maps on three kinds of dislocations, namely the a0/2〈111〉{110} screw, a0/2〈111〉{110} and a0〈100〉{001} edge dislocations. The results show that the dislocation bias is higher for the a0/2〈111〉 edge dislocation than for the a0〈100〉 edge dislocation, even though the latter possesses a larger Burgers vecto...
An explicit solution for a moving screw dislocation in a piezoelectric bimaterial is given by means of complex variables. The electroelastic fields and forces acting on the moving dislocation are obtained in closed form. As special cases, solutions for a moving screw dislocation in a piezoelectric half-plane with a free or rigid surface are obtained explicitly.
A molecular dynamics study of self-diffusion in the cores of screw and edge dislocations in aluminum
Self-diffusion along screw and edge dislocations in Al is studied by molecular dynamics simulations. Three types of simulations are performed: with pre-existing vacancies in the dislocation core, with pre-existing interstitials, and without any pre-existing defects (intrinsic diffusion). We find that diffusion along the screw dislocation is dominated by the intrinsic mechanism, whereas diffusio...
We consider a static theory of dislocations with moment stress in an anisotropic or isotropic elastoplastical material as a T (3)-gauge theory. We obtain Yang-Mills type field equations which express the force and the moment equilibrium. Additionally, we discuss several constitutive laws between the dislocation density and the moment stress. For a straight screw dislocation, we find the stress ...
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