نتایج جستجو برای: screw dislocation
تعداد نتایج: 43687 فیلتر نتایج به سال:
conclusions bosworth screw and tension band wiring are both useful procedures in patients with acj dislocation, but each should be used in the selected patients with special indications. both methods had good results during follow-up period. there was not statistically meaningful difference in the articular stability, range of motion, oss score and vast score between the two groups (p > 0.05). ...
Edge dislocations are characterised by columns of atoms in tension or in compression in a plane normal to the dislocation, above and below the slip plane. Such dislocations are conventionally viewed end-on at high resolution in transmission electron microscopes, because the tensile and compressive displacements are clearly visible. Screw dislocations are characterised by equivalent atoms in the...
The elastodynamic image forces on edge and screw dislocations in the presence of a planar-free surface are derived. The explicit form of the elastodynamic fields of an injected, quiescent screw dislocation are also derived. The resulting image forces are affected by retardation effects: the dislocations experience no image force for a period of time defined by the arrival and reflection at the ...
We study the excitation of harmonic waves in thin elastic samples by a single dislocation in arbitrary motion. We consider both screw and edge dislocations that move perpendicularly to the surfaces of the layer. In Fourier space the displacement velocity and dynamic stress fields generated by the motion of the dislocations are factored as the product of two terms: one depends on the motion of t...
We report the first ab initio density-functional study of <111> screw dislocation cores in the bcc transition metals Mo and Ta. Our results suggest a new picture of bcc plasticity with symmetric and compact dislocation cores, contrary to the presently accepted picture based on continuum and interatomic potentials. Core energy scales in this new picture are in much better agreement with the Peie...
Dislocation mobility is a fundamental material property that controls strength and ductility of crystals. An important measure of dislocation mobility is its Peierls stress, i.e., the minimal stress required to move a dislocation at zero temperature. Here we report that, in the body-centered cubic metal tantalum, the Peierls stress as a function of dislocation orientation exhibits fine structur...
Large twist-angle grain boundaries in layered structures are often described by Scherk’s first surface whereas small twist-angle grain boundaries are usually described in terms of an array of screw dislocations. We show that there is no essential distinction between these two descriptions and that, in particular, their comparative energetics depends crucially on the core structure of their scre...
Simultaneous mid third clavicle fracture and acromioclavicular joint dislocation is a rare combination injury, as a result of high-energy trauma. We report a patient with a middle third clavicle fracture and ipsilateral grade three-acromioclavicular joint dislocation, which is a rare combination. The patient wanted to get back to work as soon as possible, so the fracture was fixed with recons...
This paper presents an analytical solution for an orthotropic circular cross section bar with a magnetic coating weakened by multiple arbitrary oriented cracks under Saint-Venant torsion by means of the distributed dislocation technique. At first, the solution of the orthotropic bar with a magnetic coating weakened by a Volterra-type screw dislocation is achieved with the aid of the finite Four...
The mobility of dislocation in body-centered cubic (BCC) metals is controlled by the thermally activated nucleation of kinks along the dislocation core. By employing a recent interatomic potential and the Nudged Elastic Band method, we predict the atomistic saddle-point state of 1=2〈111〉 screw dislocation motion in BCC iron that involves the nucleation of correlated kinkpairs and the resulting ...
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