In this article, it is demonstrated that current methods of modelling plasticity as the collective motion of discrete dislocations, such as two-dimensional discrete dislocation plasticity (DDP), are unsuitable for the simulation of very high strain rate processes (106 s−1 or more) such as plastic relaxation during shock loading. Current DDP models treat dislocations quasi-statically, ignoring t...

OBJECTIVE To determine the association of popliteal artery injury with simple knee dislocations or knee fracture dislocations, and to evaluate the role of clinical assessment and colour Doppler ultrasound examination in diagnosing these injuries. METHODS The prospective case series study was done at the Liaquat National Hospital, Karachi, and comprised patients with simple knee dislocations o...

BACKGROUND The defect structure of organic materials is important as it plays a major role in their crystal growth properties. It also can play a subcritical role in "hot-spot" detonation processes of energetics and one such energetic is cyclotetramethylene-tetranitramine, in the commonly used beta form (β-HMX). RESULTS The as-grown crystals grown by evaporation from acetone show prismatic, t...

A recently introduced method of crack representation as a distribution of three-dimensional Volterra dislocations is used in conjunction with two-dimensional dislocation dynamics simulations to study the brittle to ductile transition behavior of Ferritic Steels. The crack-tip plasticity zone is represented as an array of discrete dislocations emitted from crack-tip sources. The dislocations shi...

We introduce and discuss discrete two-dimensional models for XY spin systems and screw dislocations in crystals. We prove that, as the lattice spacing ε tends to zero, the relevant energies in these models behave like a free energy in the complex Ginzburg-Landau theory of superconductivity, justifying in a rigorous mathematical language the analogies between screw dislocations in crystals and v...

We have eliminated interface defects from the mismatched Ino.()S GaO 95 As/ (001) GaAs interface by controlling the size of the growth area. 2-Jim-high pillars with different lateral shapes and dimensions were defined within the GaAs substrate before the molecular beam epitaxial growth of 3500 A of Ino.05 Gao,!" As, greater than four times the critical thickness. On the pillars, the linear dens...

Dislocation is a lattice imperfection of crystalline materials. Dislocation movement is induced during plastic deformation and influences the mechanical properties. Although the role of dislocation in mechanical properties has been well understood, the role of dislocation in electrical properties is completely lacking. Only Matthiessen's rule addresses the electrical influence of dislocations a...

The governing equation of screw dislocations in heterostructures is constructed using image method. The interface type (−1 ≤ γ ≤ 1) and distance between dislocation and interface h are considered in the new equation. The Peierls–Nabarro equations for screw dislocations in bulk and semi-infinite materials can be recovered when γ = 0 and γ = −1. The soft (γ < 0) and hard (γ > 0) interfaces can en...

To clarify the internal fatigue crack generation in a Ti-Fe-O (near a-type) alloy, microstructures, internal fatigue crack initiation sites, and dislocation structures in samples fractured during high-cycle fatigue tests at liquid nitrogen temperature were studied. The alloy contained two kinds of elongated a-phase microstructures, i.e., recovered a grains and recrystallized a grains. Untested ...