508 Works

Structural transformation of HCP metallic nanowireusing cleri-rosato potential

M.M. Aish
Sub-atomic Dynamic simulations have been carried out on some single-crystal hexagonal metals, HCP nanowires (Cd, Co, Mg, Ti, and Zr) upon application of uniaxial tension with a speed of 20 m/s and to investigate the nature of deformation and fracture. The deformation corresponds to the direction <0001> plane. A many-body interatomic potential for HCP nanowires within the second-moment approximation of the tight-binding model (the Cleri-Rosato potentials) was employed to carry out three dimensional MD simulations....

Growth of thick gallium oxide on the various substrates by halide vapor phase epitaxy

A.V. Kremleva, Sh.Sh. Sharofidinov, A.M. Smirnov, E. Podlesnov, M.V. Dorogov, M.A. Odnoblyudov, V.E. Bougrov & A.E. Romanov

Elastic properties, yield surface and flow rule of nanopowder compacts

G.Sh. Boltachev, E.A. Chingina, N.B. Volkov & K.E. Lukyashin
Методом гранулярной динамики исследуются различные процессы компактирования наноразмерной гранулированной системы, которая соответствует нанопорошку на основе оксида алюминия. Для всех процессов: рассчитаны кривые уплотнения «плотность – давление» порошкового компакта, из суммарной деформации выделены упругий и пластичный вклады, в приближении изотропного материала определены упругие модули тела. Установлена недостаточность приближения изотропности. В пространстве инвариантов тензора напряжений построена поверхность нагружения наноразмерного порошка. Выявлена неприменимость традиционного ассоциированного закона к описанию процессов деформирования оксидных нанопорошков, и предложено альтернативное правило пластического течения.

Digital core simulator - a promising method for developming hard-to-recover oil reserves technology

V.B. Betelin, V.A. Galkin, A.V. Shpilman & N.N. Smirnova
Territory of Russia, which occupies 12.8% of the Earth's territory, contains 12-13% of the forecast resources, and about 12% of the discovered oil reserves. Russia's proven oil reserves amount to approximately 13.9 billion tons of oil as of January 1, 2017 (~101 billion barrels). Oil recovery factor for proved reserves is ~17%. The increase of oil recovery factor represents a huge stockpile for raising the level of oil production in the country at low costs....

EVALUATION OF CRITICAL STRESSES FOR QUASI-BRITTLE MATERIALS AT VARIOUS LOADING RATES

Ivan Smirnov & Alexander Konstantinov
Engineering practice shows that the design of modern structures and technical components requires adapting existing methods for testing materials to dynamic load conditions. This work discusses the experimental and theoretical basis for determining and predicting critical stresses in quasi-brittle materials (such as concrete, rock, organic glass, etc.) over a wide range of loading rates provided by different test methods and equipment. Standard tests for compression, splitting and bending are presented. The incubation time approach is...

ON THE INFLUENCE OF MULTIPLE SURFACE DEFECTS ON THE BEHAVIOR OF MEDIA OF DIFFERENT RHEOLOGY

V.A. Babeshko, O.V. Evdokimova, O.M. Babeshko & I.S. Telatnikov
The behavior of coated media is investigated using the block element method under the assumption that the coating is exposed to a liquid substance that gradually leads to the destruction of the coating. It is assumed that the coating contains many defects that are parallel to each other. A similar situation occurs when the body is bent around the axis in a liquid medium, resulting in high tensile stresses in the coating. Such problems occur...

EXPERIMENTAL STUDY AND MODELING OF PRE-DEFORMATION EFFECT ON AUSTENITE TO FERRITE TRANSFORMATION

A.A. Vasilyev, D.F. Sokolov, S.F. Sokolov & A.A. Zisman
Transformation kinetics of undeformed and deformed austenite during continuous cooling has been investigated on several industrial steels. Dimensions of both prior austenite grains and ferrite grains in ferrite-pearlite structures obtained for various states of parent austenite and cooling rates were determined. Based on the obtained experimental data a physically motivated model is formulated for the ferritic transformation with allowance for the effects of deformation and concurrent recovery of austenite. Under consideration is the deformation influence...

FINITE ELEMENT HOMOGENIZATION OF PIEZOCOMPOSITES WITH ISOLATED INCLUSIONS USING IMPROVED 3-0 ALGORITHM FOR GENERATING REPRESENTATIVE VOLUMES IN ACELAN-COMPOS PACKAGE

A.B. Kudimova, D.K. Nadolin, A.V. Nasedkin, A.A. Nasedkina, P.A. Oganesyan & A.N. Soloviev
The paper considers the homogenization problems on the determination of the effective moduli of piezoceramic materials with elastic inclusions. The numerical solutions have been obtained by the effective moduli method and finite element method for the representative volumes with granular inclusions created in ACELAN-COMPOS package according to the original 3-0 algorithm. New features of this algorithm allow the user to vary different characteristics of the generated granules. The provided examples of finite element computations illustrate...

3D finite element, connected with orthogonal finite functions, in modeling and investigation of elastic homogeneous and heterogeneous material

V.L. Leontiev & I.V. Efremenkov
A novel 2D finite element (FE) associated with orthogonal finite functions (OFF, orthogonal splines) was developed for the ANSYS software and was tested early. The expansion of this method is presented here. The novel 3D FE, connected with 3D OFF is proposed for modeling and investigation of the stress-strain state of homogeneous and heterogeneous elastic bodies. The accuracy of the solutions obtained with this 3D FE is as high as for the classic ANSYS 3D...

Natural isomers of fullerenes from C20 to C28

Alexander I. Melker & Aleksandra N. Matvienko
We have systematized possible ways of forming the isomers of midi-fullerenes, namely C22, C24, C26 and C28. There are three the most natural mechanisms of their obtaining: embedding carbon dimers into initial fullerenes; fusion of carbon cupolas having the same symmetry; fusion of fullerenes having compatible symmetry. The minimum energy fullerenes are obtained through the use of the first mechanism. It is worth noting that these fullerenes conserve the topological three-fold symmetry. At the same...

Natural isomers of fullerenes from C30 to C40

Alexander I. Melker, Aleksandra N. Matvienko & Maria A. Krupina
We have systematized possible ways of forming the isomers of midi-fullerenes, namely C30, C32, C34 C36, C38 and C40. Similar to the isomers of midi-fullerenes from C20 to C28, there are three the most natural mechanisms of their formation: 1) Embedding carbon dimers into initial fullerenes; 2) Fusion of carbon cupolas having the same symmetry; and 3) Fusion of fullerenes having compatible symmetry. The energies of the fullerenes calculated through the use of molecular mechanics...

RESEARCH OF RADIATION RESISTANCE OF POLYMER COMPOSITE MATERIALS

V.D. Cherkasov, V.V. Avdonin, Y.V. Yurkin, Y.P. Scherbak, M.E. Buzoverya, I.A. Karpov & V.O. Pilshchikov
The results of comprehensive studies of radiation shielding properties and the structure of elastic self-adhesive coverings are presented. It was found that there was no change in the linear absorption coefficient of radiation, structural damage is minor at irradiation doses which are significantly higher than standard (105 Gy).

Tetrahedral miniand midi-fullerenes

Alexander I. Melker, Sergey A. Starovoitov & Ruslan M. Zarafutdinov
We have considered possible ways of forming the simplest tetrahedral fullerenes, namely elementary tetrahedron C4, truncated tetrahedron C12, half-truncated cube C16, fullerenes C28 and C36. By analogy with ionic crystals, we introduced "mathematical" compounds, which form a topological cube of two tetrahedra inserted into each other, and construct graphs for them. Combined with the graph analysis, this approach allows obtain a clear knowledge of the tetrahedral fullerene structure. We extended our model to other tetrahedral...

Sumanene and fullerene C60

Alexander I. Melker, Maria A. Krupina & Ruslan M. Zarafutdinov
In this contribution we have considered fusion reaction of carbon clusters obtained from the natural blocks of sumanene. We obtained four natural isomers of fullerene C60. Together with the fifth natural isomer found elsewhere through the use of the Endo-Kroto mechanism (dimer embedding model), now we have the structure of all the experimentally observed isomers of fullerene C60. One isomer is a perfect, the other are imperfect and differ in the number of pairs of...

Study of thermionic-tunnel component contribution in heterostructures of InGaAs/GaAs with a single quantum well by admittance methods

Y.V. Ivanova & V.I. Zubkov
A study of InxGa1-xAs/GaAs heterostructures with single quantum well (SQW) carried out by admittance methods demonstrates two competing emission mechanisms for carriers: thermionic and tunnel. The dependence of thermionic conductance peaks on the reverse bias has resonance character. We noticed a temperature independent plateau on the conductance-temperature spectra, which is always related to the tunnel nature. We guess the observed effect is the resonant tunneling through the two-barrier potential formed at the QW borders due...

Skew Brownian motion with dry friction: Pugachev-Sveshnikov approach

Sergey Berezin & Oleg Zayats
The Caughey-Dieness process, also known as the Brownian motion with two valued drift, is used in theoretical physics as an advanced model of the Brownian particle velocity if the resistant force is assumed to be dry friction. This process also appears in many other fields such as applied physics, mechanics, astrophysics, and pure mathematics. In the present paper we are concerned with a more general process, skew Brownian motion with dry friction. The probability distribution...

Use of X-ray analysis for conducting input and process control of electronics materials

Aleksandra N. Matvienko, Sergey P. Teslenko & Svetlana V. Shtelmah
The paper presents examples of using X-ray diffraction and X-ray phase analysis for monitoring and researching materials for electronic equipment. doi: 10.18720/MPM.4112019_13

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