Materials physics and mechanics

RAR RUS 97-106 Institute Silicate Chemistry of Russian Academy of Science Konakov V.G.

St.Petersburg, Russia

Institute of Problems of Mechanical Engineering RAS I.A. Ovid’ko И.А.

St.Petersburg, Russia

113263 6701854079 0000-0001-9909-2950 Institute of Problems of Mechanical Engineering RAS Sheinerman Alexander

St.Petersburg, Russia

Stress-driven migration of low-angle grain boundaries in nanocomposites with incoherent inclusions We consider migration of low-angle tilt boundaries in nanocrystalline and ultrafine-grained composites each consisting of a metallic matrix and nanoscale incoherent inclusions. Within the model, grain boundaries are considered as the walls of edge dislocations that slip in the metallic matrix but cannot penetrate nanoinclusions. Using the two-dimensional dislocation dynamics simulations, we revealed two principle modes of migration of low-angle grain boundaries. In the first mode, migrating grain boundaries are retarded by nanoinclusions, and grain boundary migration stops. In the second regime, some segments of the migrating grain boundaries are retarded by inclusions while others proceed to migrate by large distances. The transition from the first mode to the second one occurs when the resolved shear stress reaches some critical stress τc. The critical stress increases with increasing the volume fraction of inclusions, while an increase in the distance between the initial position of the migrating grain boundary and the nearest nanoinclusions can either reduce or increase the critical stress. nanocomposites; incoherent inclusions; migration of the grain boundaries https://mpm.spbstu.ru/article/2015.42.1/ MPM224_01_konakov.pdf

RAR RUS 107-118 Tver State University Zubchaninov

Tver, Russia

Tver State University Alekseev

Tver, Russia

Tver State University Alekseeva

Tver, Russia

Mathematical modeling of plastic deformation of materials on complex flat trajectories The basic equations and relations of the theory of elastic-plastic deformation processes in plane problems are presented for arbitrary paths, with both the generalized Baushinger's effect under complex loading and secondary plastic deformation taken into consideration. In solution of the basic equations using universal approximations of functionalities of processes, the fourth-order accuracy Runge-Kutta numerical method is utilized. In order to validate the reliability of calculated data, results of our simulations are compared with the corresponding experimental data obtained using the SN-EVM testing system. elasticity; plasticity; complex loading; mathematical model; trajectory of deformation; vector and scalar properties of materials; SN-EVM test stand https://mpm.spbstu.ru/article/2015.42.2/ MPM224_02_zubchaninov.pdf

RAR RUS 119-128 Siberian State Industrial University Sarychev

Novokuznetsk, Russia

Siberian State Industrial University Nevskii

Novokuznetsk, Russia

Siberian State Industrial University Gromov

Novokuznetsk, Russia

Biphase filtrational model of flow materials at superplastic deformation Considering plastically deformed material as a two-phase heterogeneous medium, the filtration model of plastic deformation has been proposed. The laws of momentum and mass conservation for each component, the equations of state, and boundary conditions are used for the model. The first component of the medium is treated as an elastic one, which is responsible for the structural transformations, and the second component is a plastic one, which is not associated with structural transformations. The filtration ratio between the phases has been found. The search for solutions in the form of a traveling wave has been performed. As a result of calculations, the solution in the form of "shock transition" and the speed limit of its propagation have been found. For traveling waves, the dispersion equation and the critical wavelength, at which instability takes place, have been determined. plastic waves; plastic deformation; laws of conservation of momentum and mass; traveling wave; dispersion equation https://mpm.spbstu.ru/article/2015.42.3/ MPM224_03_nevskii.pdf

RAR RUS 129-138 Saint Petersburg State University E.G. Zemtsova

St.Petersburg, Russia

St.Petersburg State University Morozov

St.Petersburg, Russia

Ufa State Aviation Technical University Valiev R.Z.

Ufa, Russia

Saint Petersburg State University Smirnov

St.Petersburg, Russia

Study of conditions for the increase of surface hydrophobization of nanostructured titanium with titanium organic nanostructures brush type on the surface The paper considers the regulation of the structural characteristics of the surface of the new medical material ─ nanotitanium using the method of molecular layering due to the application of nanostructured titaniumorganic coating brush type with a different degree of hydrophobicity. Regulation of the degree of hydrophilicity or hydrophobicity of the surface of nanotitanium with titaniumorganic nanostructures was realized by varying the conditions of synthesis of end functional groups and their chemical composition. The paper shows the possibility of controlling the surface nanotitanium by chemical structure, and found the conditions of synthesis, allowing aims to change contact angle in the range 42°- 90°. titanium organic nanostructure; nanostructured matrix of titanium; severe plastic deformation; hydrophobic surface; bioactive surface; bio-compatible coating https://mpm.spbstu.ru/article/2015.42.4/ MPM224_04_smirnov.pdf

RAR RUS 139-144 Menoufia University Aish

Egypt

I.I. Polzunov Altai State Technical University Starostenkov

Barnaul, Russia

Modeling and simulation of Ni nanofilm using Morse pair potential Morse potentials were employed to carry out three-dimensional molecular dynamics simulations. A computer experiment was performed at the temperature corresponding to 300 K and 1000 K. MD simulation was used to investigate the effect of cross-sectional area of Ni nanofilm on the nature of deformation and fracture. The engineering stress–time diagrams obtained by the MD simulations of the tensile specimens of these Ni nanofilms showed a rapid increase in stress up to a maximum followed by a gradual drop to zero when the specimen was failed by ductile fracture. The feature of deformation energy can be divided into four regions: quasi-elastic, plastic, flow, and failure. The results shows that breaking position depends on the nanofilm cross-sectional area. three-dimensional molecular dynamics simulation; Morse potentials; Ni nanofilm; deformation; fracture https://mpm.spbstu.ru/article/2015.42.5/ MPM224_05_aish.pdf

RAR RUS 145-153 59122315900 0000-0002-1572-2108 Kurukshetra University Kumar Rajneesh

Kurukshetra, India

Himachal Pradesh University Shimla Sharma

Shimla, India

Himachal Pradesh University Shimla Devi

Shimla, India

Stability of stratified viscoelastic Rivlin-Ericksen (model) fluid/plasma in the presence of quantum physics saturating a porous medium The present investigation deals with the quantum effects on the Rayleigh - Taylor instability in an infinitely electrically conducting inhomogeneous stratified incompressible viscoelastic fluid/plasma through a porous medium. The linear growth rate is derived for the case where a plasma with exponential density, viscosity, viscoelasticity and quantum parameter distribution is confined between two rigid planes. The solution of the linearized equations of the system together with the appropriate boundary conditions leads to derive the dispersion relation (the relation between the normalized growth rate and square normalized wavenumber) using normal mode technique. The behavior of growth rate with respect to quantum effect and kinematic viscoelasticity are examined in the presence of porous medium, medium permeability and kinematic viscoelasticity. It is observed that the quantum effects bring more stability for a certain wave number band on the growth rate on the unstable configuration. Rivlin-Ericksen (Model); viscoelastic; Rayleigh-Taylor instability; quantum plasma; porous medium https://mpm.spbstu.ru/article/2015.42.6/ MPM224_06_kumar.pdf

RAR RUS 154-162 Institute of Problems of Mechanical Engineering RAS I.A. Ovid’ko И.А.

St.Petersburg, Russia

113263 6701854079 0000-0001-9909-2950 Institute of Problems of Mechanical Engineering RAS Sheinerman Alexander

St.Petersburg, Russia

Transfer of plastic deformation through graphene interfaces in metal-graphene nanocomposites A model is suggested that describes the transfer of plastic deformation through graphene interfaces in metal-graphene composites. Within the model, the transfer of plastic deformation is realized through the formation of a dislocation pileup in a metallic grain, followed by the generation of a glide dislocation loop in a neighboring grain under the action of the applied stress and the stress field of the dislocation pileup. We calculated the critical stress for the transfer of plastic deformation through graphene interfaces as functions of the grain size d and the thickness h of the graphene interface. nanocomposite; metal; graphene; plastic deformation https://mpm.spbstu.ru/article/2015.42.7/ MPM224_07_ovidko.pdf

RAR RUS 163-177 Donetsk Institute for Physics and Engineering named after O.O. Galkin, National Academy of Sciences of Ukraine Pashynskaya

Donetsk, Ukraine

Donetsk Institute for Physics and Engineering named after O.O. Galkin, National Academy of Sciences of Ukraine Zavdoveyev

Donetsk, Ukraine

Donetsk Institute for Physics and Engineering named after O.O. Galkin, National Academy of Sciences of Ukraine Metlov

Donetsk, Ukraine

Donetsk Institute for Physics and Engineering named after O.O. Galkin, National Academy of Sciences of Ukraine Nepochatikh

Donetsk, Ukraine

Donetsk Institute for Physics and Engineering named after O.O. Galkin, National Academy of Sciences of Ukraine Maksakova

Donetsk, Ukraine

Donetsk Institute for Physics and Engineering named after O.O. Galkin, National Academy of Sciences of Ukraine Tkachenko

Donetsk, Ukraine

Non-trivial changes in physical and mechanical properties and structure of low carbon steel wire, produced by rolling with shear and cold drawing The hereditary influence of the initial wire rod structure on the structure and physical-mechanical properties of the steel wire 08G2S, manufactured by rolling with shear, combined with the cold drawing is investigated. For comparison, the structure and properties of samples of the same steel wire, produced by commercial technology of rolling and drawing, were investigated. It has been shown that formation of the special structural state of low carbon steel by rolling with shear provides the increasing of the ductility and electric conductivity of wire in combination with satisfactory technological plasticity. rolling with shear; low-carbon steel; structure; resistivity; properties https://mpm.spbstu.ru/article/2015.42.8/ MPM224_08_pashinskaya.pdf

RAR RUS 178-186 Institute for Problems of Mechanical Engineering of the RAS Semenov

St.Petersburg, Russia

Modeling of deformation and fracture of nanotitan cylinder specimens coated by nanoceramic on the basis of zirconium dioxide under local impacts Contact of an elastic ball stamp and a titanium cylinder with a ceramic coating based on zirconium dioxide is considered. It is shown that at contact interaction tensile stresses occur in the coating, which can lead to cracking of the coating. The dependencies of the intensity of these stresses on the elastic properties of the spherical stamp, stamp radius and the yield strength of titanium are examined. It is shown that nano-titanium due to its high yield strength is preferable at the local impacts, as compared to conventional coarse-grained titanium for such designs. contact interaction; elastic ball stamp; titanium cylinder; ceramic coating; zirconium dioxide; modeling of deformation and fracture https://mpm.spbstu.ru/article/2015.42.9/ MPM224_09_semenov.pdf

RAR RUS 187-193 FSBEI HPE “Kh.M. Berbekov Kabardino-Balkarian State University” Mikitaev

Nalchik, Russia

FSBEI HPE “Kh.M. Berbekov Kabardino-Balkarian State University” Kozlov

Nalchik, Russia

The structural model of strength of nanocomposites poly(methyl methacrylate)/functionalized carbon nanotubes The quantitative structural model of strength of nanocomposites polymer/carbon nanotubes was considered. It has been shown that the structure of carbon nanotubes in polymer matrix has a responsible effect on the mechanical properties of these nanomaterials. Obtaining the critical structural points (percolation threshold of carbon nanotubes, critical radius of their "closed" ring-like structures) defines a significant reduction of strength. nanocomposite carbon nanotubes structure strength interfacial regions https://mpm.spbstu.ru/article/2015.42.10/ MPM224_10_mikitaev.pdf

RAR RUS 194-200 ITMO University Rozhkov

St.Petersburg, Russia

ITMO Univesity Kolodeznyi

St.Petersburg, Russia

ITMO University Smirnov A.M.

St.Petersburg, Russia

ITMO University V.E. Bougrov

St.Petersburg, Russia

F-1445-2014 7202768874 0000-0003-3738-408X ITMO University Romanov Alexey alexey.romanov@niuitmo.ru

St.Petersburg, Russia

Comparison of characteristics of Schottky diodes based on β-Ga2O3 and other wide bandgap semiconductors Electrical characteristics of Schottky diode (SD) Au/β-Ga2O3 were analyzed both theoretically and with the use of finite element method. It was shown that Schottky barrier height for Au/ β-Ga2O3 is 1.23 eV and threshold voltage is ~ 0.6 V with current ~ 1 µА. Comparative analysis of the properties of SD Au/β-Ga2O3 and devices based on various wide bandgap semiconductors including 4H-SiC, GaN and AlGaN has been performed. We demonstrated that SD Au/β-Ga2O3 had smaller reverse current than Au/GaN and Ni/4H-SiC. Calculated breakdown voltage for SD Au/β-Ga2O3 was 2513 V. Schottky diode; wide bandgap semiconductors; reverse current; breakdown voltage https://mpm.spbstu.ru/article/2015.42.11/ MPM224_11_rozhkov.pdf