107 Works

Influences of solvent types on the formation of graphene in the electrochemical exfoliation method

T. Kurniawan, M.A. Anwar, R. Oktiani, R. Ragadhita, A.B.D. Nandiyanto & M. Aziz
The aim of this study was to evaluate the effect of different solvents in sonication process on the formation of graphene from the electrochemical exfoliation of graphite. In short, graphite rod was exfoliated by electrochemical process with ammonium sulfate as salt-electrolyte. The exfoliated powder then sonicated under two different solvents, which are Dimethylformamide (DMF) and aqueous solution to form graphene. It was found that similar structure of graphene was obtained from both types of solvent....

MECHANISM OF MOLECULE MIGRATION OF CARBON AND SILICON MONOXIDES IN SILICON CARBIDE CRYSTAL

S.A. Kukushkin, A.V. Osipov & E.V. Osipova
The main processes occurring during the migration of molecules of carbon monoxide CO and silicon monoxide SiO gases through a layer of monocrystalline silicon carbide SiC of a cubic polytype have been described by the ab initio methods. This problem arises when a single-crystal SiC layer is grown by the method of coordinated substitution of atoms due to the chemical reaction of a crystalline silicon substrate with the CO gas. The reaction products are epitaxial...

THE INFLUENCE OF GAMMA RAYS RADIATION ON OPTICALLY INDUCED LUMINESCENCE OF COPPER-CONTAINING POTASSIUM-LITHIUM-BORATE GLASS

P.S. Shirshnev, V.A. Spiridonov, D.I. Panov, E.V. Shirshneva-Vaschenko, A.R. Gafarova, R.M. Eremina, A.E. Romanov & V.E. Bougrov
The paper presents the results of potassium-lithium-borate glass containing copper ions investigations. The glass was irradiated by 1.25 MeV gamma rays. The dose of radiation was 360 Gy. The exciting of the irradiated glass at 360 nm led to the long-wavelength photoluminescence band shift from 635 nm to 671 nm in comparison with non-irradiated glass. A new luminescence band at 685 nm also appeared for excitation wavelength 405 nm in the irradiated glass. It has...

THE STRUCTURAL TRANSFORMATION AND MECHANICAL STRENGTH OF Ni, Ti NANOWIRES AND NITINOL ALLOYS AT VARIOUS VACANCY RATES: MOLECULAR DYNAMIC STUDY USING CLERI-ROSATO POTENTIAL

M.M. Aish
A many-body interatomic potential was used for Nickel (Ni) crystal with facecentered cubic (FCC) lattice and Titanium (Ti) with hexagonal close-packed (HCP) lattice and Nitinol alloys within the second-moment approximation. The tight-binding model (the Cleri and Rosato potentials) was employed to carry out three dimensional molecular dynamics simulations upon application of uniaxial tension at nanoscale of studied materials, which contained various vacancy rates. We performed molecular dynamics (MD) simulations to study the yield mechanisms in...

Numerical method of single-crystal turbine blade static strength estimation taking into account plasticity and creep effects

Boris Vasilyev & Alexander Selivanov
To increase the reliability of single-crystal blade durability estimations a phenomenological model of single crystal superalloy plasticity based on the use of an “equivalent” direction and its software implementation has been developed. The relative orientation between principal stresses and single-crystal (SX) axes is considered by this direction. In order to study the effect of crystallographic orientation (CO) on the characteristics of a single-crystal material, a series of tests was carried out at various temperatures under...

Comparative study of adsorption of ozone molecule on pristine and Si doped Single Wall Carbon Nanotube by density functional theory

R.G. Atram & M.R. Sonawane
We report comparative study of ozone adsorption on pristine Single Walled Carbon Nanotube (SWCNT) (8, 0) and Silicon doped Single walled Carbon Nanotube (Si – SWCNT) by density functional theory calculations based on DeMol3 code. Importance is given to the effects of silicon doping in carbon nanotube for comparative study of adsorption of ozone. The results show that silicon doping keeps the semiconducting character of pure carbon nanotubes with reduction in band gap from 0.71...

Effect of bamboo weight faction on mechanical properties in non-asbestos composite of motorcycle brake pad

Y. Sukrawan, A. Hamdani & S.A. Mardani
This study aims to determine the mechanical properties of the use of brake pads based on composite materials from bamboo fiber, and to evaluate the effect of replacement of brake pad material made from asbestos with natural materials to avoid the impacts of asbestosis substances, such as cancer. The method used several stages: weighing, mixing, inserting materials in molding, compacting, and sintering. The stages were carried out in three types of composites: Composite 1 (40%...

Dynamic fracture of ceramic plates due to impact loading. Numerical investigation

V.A. Bratov & N.A. Kazarinov
The paper presents comparative numerical analysis of two ceramic materials subjected to impact loading. ZrO2(Y2O3) and Al2O3 ceramics are studied. The main objective of the work is to study influence of various material parameters on ballistic performance of ceramic materials and on characteristics of the dynamic fragmentation process. The applied numerical scheme is based on finite element method and incubation time fracture criterion. Results on fracture surface area, residual impactor velocity, fragment size distribution are...

Neural networks and data-driven surrogate models for simulation of steady-state fracture growth

A.V. Kalyuzhnyuk, R.L. Lapin, A.S. Murachev, A.E. Osokina, A.I. Sevostianov & D.V. Tsvetkov
This work is devoted to an assessment of the application of machine learning algorithms in the prediction of a fracture's aspect ratio caused by the hydraulic fracturing. By the aspect ratio in this work is assumed the ratio of the larger half-axis of the fracture to the smaller one. The study shows the prospects of applying data-driven surrogate model methods (deep neural networks learning from data simulated by means of traditional solvers) to particle dynamics...

Supercomputing analysis of fan-shaped waves in the Earth's crust at the depth of seismic activity

V.M. Sadovskii & O.V. Sadovskaya
The high-speed process of tectonic faults formation in zones of seismic activity of the Earth's crust is analyzed in a plane strain state based on the model of elastic blocks interacting through a domino-structure under conditions of strong hydrostatic compression. Numerical simulation of the dynamics of emerging fan-shaped waves is performed by means of the developed computational algorithm and computer program for multiprocessor supercomputers of cluster architecture.

The influence of stress triaxiality on ductility of α titanium alloy in a wide range of strain rates

V.V. Skripnyak, A.A. Kozulyn & V.A. Skripnyak
This work aimed to evaluate the combined effect of stress triaxiality and strain rate on the tensile behavior of the titanium alloy. The results of experimental studies and numerical modelling of the mechanical behavior of alpha titanium alloys were received and summarized. This paper presents the results of the research of mechanical behavior of titanium alloy VT 5-1 (this is an analog of Ti-5Al-2,25Sn) in a wide range of strain rates (from 0.001 to 1000...

Modeling of elastoplastic deformation of structural steel by a trajectory containing three circles touching internally

V.G. Zubchaninov, A.A. Alekseev, V.I. Gultiaev & E.G. Alekseeva
To verify the mathematical model of the theory of processes, numerical calculations of the complex elastoplastic deformation of St3 steel along a flat curvilinear strain trajectory under combined tension-compression with torsion were carried out. The numerical calculations are compared with the experimental data obtained by the authors on the experimental complex SN-EVM on thin-walled tubular specimen. It is shown that the used mathematical model qualitatively and quantitatively satisfactorily describes the main effects of complex plastic...

Femtosecond transient absorption spectroscopy of maghemite nanoparticles loaded with gold nanoparticles

Masahiro Okazaki, Yusuke Ishii & Akihiro Furube
Photocatalytic water splitting is very useful for solar energy conversion. Iron oxides are attracting a lot of interests due to absorption in the visible region. However, iron oxides have poor conductivity. As one of solutions, the photocatalytic performance may be enhanced with loaded gold nanoparticles (Au-NP) by the characteristic optical absorption and the charge trapping nature. In this study, hybrid material of maghemite (γ-Fe2O3) and Au-NP (denoted as Au-Fe2O3) was prepared and the photo-generated carrier...

Mechanical aspects of the behavior of the surface of coated bodies when exposed to corrosive liquid

V.A. Babeshko, O.V. Evdokimova, O.M. Babeshko, V.L. Shestopalov & V.S. Evdokimov
The block element method is used to study the behavior of a coated material under the assumption that the surface is exposed to a corrosive liquid medium that can destroy the coating. It is assumed that the destruction begins with the formation of vertical local cracks in the coating, which then grow and lead to the exposure of the unprotected surface. Assuming the possibility of modeling a liquid layer by shallow water equations, the block...

Simulation of residual distributions stress in welded connection

E.E. Abashkin, A.A. Burenin, S.G. Zhilin, O.N. Komarov & A.V. Tkacheva
The search for technological options for obtaining a solid assembly with small values of deformations determines the need to use a combined thermal effect on the zone of connection of extended elements made of carbon steel. Prediction of residual stress values occurring in the heat-affected zone of an assembly is difficult because of the influence of a significant number of factors: heat removal conditions, volume and material properties, etc. To calculate the residual stresses in...

Pantographic metamaterials: a view towards applications

Francesco dell'Isola, Ivan Giorgio, Luca Placidi, Mario Spagnuolo, Patrice Peyre, Corinne Dupuy, Justin Dirrenberger, Marek Pawlikowski & Leonid Igumnov
The purpose of this article is to show the basic characteristics of the so-called pantographic metamaterial. Here we underline how the microstructure provides some exotic properties and, in principle, implies the second gradient nature of this type of metamaterial. Thanks to the development of additive manufacturing technology (especially in the field of metallurgy) we are now able to produce real samples and carry out experimental measurements to validate the proposed models. In this article we...

Structural characterization of bulk (AlXGa1-X)2O3 crystals grown by the Czochralski method

A.V. Kremleva, D.A. Kirilenko, I.G. Smirnova, V.E. Bougrov & A.E. Romanov
Results of structural characterization of (AlxGa1-x)2O3 single crystals grown from the melt with Al content x up to 0.04 are presented. Bulk (AlxGa1-x)2O3 crystals were grown by exploring the Czochralski method [1]. Transmission electron microscopy (TEM) was used to investigate defect structure of the material with various composition, X-ray diffractometry was used to measure Al content x, to inspect crystallography of the growth facets and to characterize the structure quality of the samples. Possible types...

Axial misfit stress relaxation in core-shell nanowires with hexagonal core via nucleation of rectangular prismatic dislocation loops

S.A. Krasnitckii, A.M. Smirnov, K.D. Mynbaev, L.V. Zhigilei & M.Yu. Gutkin
A theoretical model of axial misfit stress relaxation in core-shell nanowires with hexagonal cross section of the core through the nucleation of prismatic dislocation loops is suggested. Different nucleation sites of the loops in core-shell nanowires are considered. The energy change caused by the loop nucleation is calculated. The critical condition for the onset of the loops is given and analyzed in detail. The most favorable sites in nanowires and the optimal loop shape are...

Czochralski grown (AlxGa1-x)2O3 crystals with variable Al content

P.N. Butenko, D.I. Panov, A.V. Kremleva, D.A. Zakgeim, A.V. Nashchekin, I.G. Smirnova, D.A. Bauman, A.E. Romanov & V.E. Bougrov
We propose a technuque of liquid-phase growth of (AlxGa1-x)2O3 crystals with variable and controlled Al content in them. When using the Czochralski growth process Ga2O3 melt was dosed by sapphire seed. By applying of the special growth zone and the regulating the process parameters, a series of crystal samples with Al content varying from 0.51 to 4.68 % at. was obtained. In addition to the standard setting of the geometry and weight of the crystals...

Morphology investigation of nanoporous anodic alumina films with image analysis

N.V. Lushpa, H.T. Dinh, K.V. Chernyakova & I.A. Vrublevsky
Aluminum films approximately 100 nm thick were deposited on silicon substrates (SiO2 / Si) by thermal evaporation in a vacuum. Porous anodic alumina films were obtained in a potentiostatic mode at 20 V in 0.3 M aqueous solution of oxalic acid and 1.8 M aqueous solution of sulfuric acid. The main pore diameter was determined using the ImageJ software from SEM images. An algorithm determining the pore diameter in porous anodic alumina films was developed....

Influence of LCV bearing stiffness on its static and dynamic characteristics of stability and steerability

Anton V. Tumasov, Sergey Y. Kostin, Danila A. Butin, Aleksey A. Vasiliev & Pavel V. Sereda
Study of the frame stiffness influence on vehicle dynamics and stability of light commercial vehicle is done. The simulations were conducted by using ADAMS/CAR software package. The model approbation was carried by comparing the results of simulation and real tests. The objects of the studies were four different models of a vehicle having different parameters of the frame rigidity. For the needs of the research where conducted such tests as: "going into corner", "line change"...

Mechanical impulse enhancement in a microsystem based on nanoporous silicon combustion

S.K. Lazarouk, A.V. Dolbik & V.A. Labunov
Nanostructured porous silicon impregnated by solid state oxidizer has been studied in order to provide the mechanical impulse for jet-propulsion microsystems. The system with jet-propulsion motion on a silicon chip has been tested for impulse measurements. The silicon chip has been fastened on a carrying platform through an elastic spacer. The elastic spacer promotes the combustion and prevents from explosion of porous silicon fast oxidation. It is shown that such a microsystem gains the impulse...

Numerical simulation of hypervelocity impacts of variously shaped projectiles with thin bumpers

M.V. Silnikov, I.V. Guk, A.I. Mikhaylin, A.F. Nechunaev & B.V. Rumyantsev
The paper presents a numerical simulation of hypervelocity impacts of variously shaped projectiles with thin bumpers. A numerical model was verified using a full-scale experiment of hypervelocity impact of a sphere with thin aluminum-alloy bumper. Hypervelocity impacts of nonspherical projectiles of different spatial orientation with thin bumpers were also numerically investigated. The investigations show that a hypervelocity impact of a nonspherical projectile advancing with its sharp edge towards the bumper results in a denser debris...

Applied theory of bending vibrations of a piezoelectric bimorph with a quadratic electric potential distribution

A.N. Soloviev, V.A. Chebanenko, I.A. Parinov & P.A. Oganesyan
An applied theory of cylindrical bending vibrations of a bimorph plate is developed, which takes into account the nonlinear distribution of the electric potential in piezoelectric layers. Finite-element analysis of this problem showed that such distribution arises when solving the problems of finding the resonant frequencies and modes of vibration or in the case of forced oscillations during their mechanical excitation, when the electric potentials on the electrodes are zero. The quadratic distribution of the...

NUCLEATION OF ISLANDS WITH VERTICAL OR TRUNCATED CORNER FACETS IN VAPOR-LIQUID-SOLID NANOWIRES

V.G. Dubrovskii, Zh.V. Sokolova, M.V. Rylkova & A.A. Zhiglinsky
We develop a model for nucleation of islands in vapor-liquid-solid nanowires with either vertical or truncated corner facets. Under the assumption of two-dimensional geometry of the growing island, it is shown that the earlier energetic condition for the truncated edge at the growth interface is modified by chemical potential. Therefore, the islands may nucleate at the trijunction during growth even if the truncation is preferred at the no growth conditions on surface energetic grounds. This...

Registration Year

  • 2019
    107

Resource Types

  • Text
    107

Affiliations

  • Peter the Great St. Petersburg Polytechnic University
    10
  • N. I. Lobachevsky State University of Nizhny Novgorod
    8
  • Institute of Problems of Mechanical Engineering
    8
  • ITMO University
    5
  • Ioffe Institute
    4
  • Bauman Moscow State Technical University
    3
  • //ror.org/02x91aj62:Peter the Great St. Petersburg Polytechnic University
    3
  • Tver State Technical University
    2
  • Kuban State University
    2
  • Saint Petersburg State University
    2