65 Works

Disclination models of transformation of icosaedric copper particles during their growth during electric crystallization

А.А. Vikarchuk, N.N. Gryzunova & S.S. Manokhin
For the first time, copper particles in the form of truncated micron-sized icosahedrons were experimentally obtained by electrodeposition, their morphology and internal structure were investigated. It is shown that fullerene-like copper microparticles grow from non-crystalline spherical nanoparticles and are transformed during electrocrystallization into perfect icosahedrons, which have a more stable shape and structure. The disclination models for the conversion of nanoparticles into icosahedral microparticles are developed and described.

Analysis of the degree isotropic deformation, strength and structure steel samples after severe deformation by shifting

A.P. Zhilyaev, A.G. Raab, I.S. Kodirov & G.I. Raab
The article presents the results of computer simulation and physical research of severe deformation by free torsion of long-length specimens with a round cross-section of steel 10 at a temperature of 600°C. Based on virtual approaches in the Deform 3D software package, the deformed state of the samples, including the distribution of accumulated strain in the bulk workpiece, was investigated. A physical experiment was carried out, the structure and microhardness in the longitudinal section of...

PROBING OF POLYCRYSTALLINE MAGNESIUM AT ULTRASONIC FREQUENCIES BY MECHANICAL SPECTROSCOPY

V.V. Kaminskii, Y.V. Lyubimova & A.E. Romanov
In the present work, using the method of a composite piezoelectric oscillator at a frequency of 99-102 kHz, polycrystalline magnesium was studied under two types of treatment: deformation and subsequent annealing. The influence of these types of treatments on changes in the dislocation density and such an important structurally sensitive parameter as the dynamic Young's modulus has been established. The values of micro-yield stress are determined. With a longitudinal deformation of 1.7%, at the strain...

Quantum chemical modeling bismuth-based clusters

E.N. Gribanov, O.I. Markov & Yu.V. Khripunov
The article presents the results of calculations of the structure and energy parameters of BiN : Bi8, Bi18 , Bi50 , Bi98 , Bi162 bismuth nanoclusters using quantum chemical methods. An extrapolation estimate of the number of atoms in a cluster with a zero band gap is made. The band gap width of bismuth nanoclusters passivated by Bi HmN hydrogen is calculated . The results of quantum chemical modeling of Bi Sb ( ) N...

INFLUENCE OF AGING ON FATIGUE AND CREEP PROPERTIES OF POLYURETHANE

A.R. Arutyunyan
Polymers and polymer-based materials are intensive implemented in many areas of engineering practice. These applications frequently have a very high performance demand, which makes their long-term characteristics of paramount importance. These materials were subject to degradation due to environmental factors, including light, temperature, stress, and others. Because of aging process, the physical and mechanical properties of these materials are significantly changed. This paper is devoted to the experimental investigations of this problem. The research program...

TEMPERATURE EFFECT ON THE PROCESS OF WEAR OF A FIBROUS COMPOSITE UNDER HIGH LOAD CONDITIONS

A.G. Shpenev
A model of the fibrous composite material friction and wear process is constructed taking into account the heating of the friction surface. The inhomogeneous temperature expansion of the composite components and the resulting fiber/matrix slippage near thefriction surface and the friction surface profile change is considered. The influence of temperature on the distribution of stresses in the fiber and matrix and on the roughness of the friction surface of the composite is determined.

DETERMINATION OF MECHANICAL PROPERTIES OF GRAPHENE REINFORCED TETRA-GEDVA NANOCOMPOSITE

Debaditya Chakraborty Chakraborty, Ayush Rathi Rathi, Akansha Singh & Ashish Goyal
In the present study, effects of aspect ratio and perforation on the elastic response of graphene nanosheet (GNS)-embedded Tetra GEDVA (triglycidyl ether of divanillyl alcohol) nanocomposite plate are studied by material studio analysis. A dense amorphous cell is created using the Forcite module and simulation is performed. Young's modulus is predicted at varying strain rates from 0-1 GPa. The study conducted coarse-grained molecular dynamics (MD) simulations of Nano-indentation of PMMA (polymethyl methacrylate) polymer to study...

CONTROL OF (AL,GA)P COMPOSITION IN SELF-CATALYZED NANOWIRE GROWTH

Nickolay V. Sibirev, Vladimir Fedorov, Igor V. Shtrom, Alexey D. Bolshakov & Yury Berdnikov
Composition of ternary III-V nanowires became a subject of recent intensive studies inspired by several optoelectronic applications. Among these nanostructures, phosphide nanowires possess a wider bandgap making it especially promising for applications operating in the green visible range. However, unlike other III-V materials, the growth of AlGaP nanowires remains rather unexplored. In this work, we model the stationary composition of self-catalyzed AlGaP grown by molecular beam epitaxy. We show that under a wide range of...

STRUCTURAL BEHAVIOR OF FG-CNT CYLINDRICAL PANEL: INFLUENCE OF NON-UNIFORM TEMPERATURE FIELD

Vinod Bhagat & P. Jeyaraj
In this study, the influence of non-uniform temperature field and temperature-dependent properties on buckling and free vibration behavior of functionally graded carbon nanotube (FG-CNT) reinforced composite cylindrical panel is investigated. For the structural analysis, the finite element method and modal assurance criterion (MAC) analysis are performed. It is found that the temperature-dependent properties and nature of temperature variation fields affect the thermal buckling strength of the panel greatly. The results from MAC analysis reveals that...

STUDY OF RADIAL VIBRATIONS IN THICK WALLED HOLLOW DISSIPATIVE POROELASTIC SPHERICAL SHELL ON ELASTIC FOUNDATION

Rajitha Gurijala & Malla Reddy Perati

Natural isomers of fullerenes from C4 to C20

Alexander I. Melker & Aleksandra N. Matvienko
We have systematized possible ways of forming the isomers of mini-fullerenes, namely elementary fullerenes: tetrahedron C4, triangular prism C6, cube C8, pentagonal prism C10, hexagonal prism C12, as well as their derivatives, which were obtained by joining elementary fullerenes. Combined with the graph analysis, this approach allows obtain a clear knowledge of their structure. Among them there are barrel-shaped fullerenes: C12, C16, C20; tetrahedral ones C12 and C16; bi-shamrocks C14 and C18, bipyramids C14 and...

Modeling microstructure evolution during thermomechanical processing and heat treatment of steels and predicting their mechanical properties

A.A. Vasilyev, D.F. Sokolov & S.F. Sokolov
An integral computer model/program AusEvol Pro was developed to describe the evolution of steel microstructure during thermomechanical processing (hot rolling, forging), as well as subsequent heat treatment (normalization, tempering), and to evaluate the final mechanical properties (yield stress, tensile stress, elongation), hardness and impact toughness. The program implements a set of physically based models that allow quantitative description of all significant processes of steel structure formation with account of the effects of chemical composition both...

Nano- and microparticle aggregation: unique optical vectors for control

Alexandra G. Bezrukova & Olga L. Vlasova
The multiparameter analysis of simultaneous optical data for systems of nano- and/or micro-particles (3D disperse systems, dispersions, colloids, ensembles with the average diameter less than 10 micrometers) can be presented as the system characteristics characterized by N-dimensional unique vectors of optical parameters that can elucidate changes in the state of system particles. The application of ND unique optical vector approach is shown for several biomedical dispersions at the processes of aggregation. This approach can serve...

Element-free numerical modeling with discrete gradient and its application to crystal defects

A.A. Zisman
The gradient operation has been extended to discrete data in terms of nodal coordinates. On this ground, the nodal strains and related stresses are expressed directly in terms of nodal displacements and the stress divergence in terms of nodal stresses. To make use of truly discrete modeling in computational solid mechanics, the stress balance equation is formulated. For a case study, the latter is applied to an edge dislocation where atom positions of a dislocated...

Control of the mechanical properties and microstructure of laser welded joints of the aluminum alloy V-1461 after heat treatment

A.G. Malikov, A.M. Orishich, E.V. Karpov & I.E. Vitoshkin
The paper presents the investigations of the influence of the thermal postprocessing on the mechanical characteristics and microstructure of the welded aluminum alloy V-1461 of the system Al-Cu-Li. The temperature and time characteristics of the quenching and artificial ageing processes of the laser welded connections have been optimized in order to have the ultimate tensile stress, yield stress, and relative elongation, as well as the microstructures close to the respective characteristics of the basic alloy....

Deposition kinetics and boundary layer theory in the chemical vapor deposition of β-SiC on the surface of C/C composite

H. Aghajani, N. Hosseini & B. Mirzakhani
In this study, SiC was deposited on carbon/carbon (C/C) composite substrate using chemical vapor deposition (CVD) method to investigate the kinetics of the deposition process. Therefore, the time, temperature, precursor composition (SiCl4:N2:CH4) and substrate position in the reactor were varied to evaluate the deposition rate. X-ray diffraction (XRD) method was used to characterize the phase composition and calculate the grain size and the texture coefficient of the coatings. Field emission scanning electron microscopy (FESEM) was...

VIBRATION OF A HYDROSTATIC STRESSED PIEZOELECTRIC LAYER EMBEDDED ON GRAVITATING HALF SPACE WITH SLIDING INTERFACE BOUNDARY

Rajendran Selvamani
In this paper, an analytical model is developed to study the influence of initial hydrostatic stress and piezo elasticity on elastic waves in a piezoelectric layer embedded on a gravitating half space with slip interface. The piezo electric layer considered for this study is hexagonal (6mm) material. The problem is described using equations of linear elasticity with initial hydrostatic stress and piezo elastic inclusions. Displacement functions in terms of velocity potential are introduced to separate...

TERAHERTZ EMITTERS BASED ON NEGATIVE-U MATERIALSFOR MEDICAL APPLICATIONS

N.T. Bagraev, P.A. Golovin, V.S. Khromov, L.E. Klyachkin, A.M. Malyarenko, V.A. Mashkov, B.A. Novikov, A.P. Presnukhina, A.S. Reukov & K.B. Taranets
The characteristics of terahertz (THz) irradiation generated by a silicon nanosandwich structure under the conditions of a stabilized drain-source current are demonstrated. The frequency of irradiation arising from the quantum Faraday effect is determined by the parameters of microcavities embedded in the edge channels of a silicon nanosandwich structure confined by the negative-U centers. The obtained characteristics of a compact THz irradiation source determine the basis for highly effective medical applications.

THE BINDING ENERGY OF IMPURITY ATOMS C, N, O WITH EDGE DISLOCATIONS AND THE ENERGY OF THEIR MIGRATION ALONG DISLOCATION CORE IN Ni, Ag, Al

G.M. Poletaev, I.V. Zorya, R.Y. Rakitin & L.G. Glubokova
Using the molecular dynamics method, the binding energies of impurity atoms of light elements C, N, O with edge dislocations, and the energy of their migration along with dislocation core in metals with fcc lattice Ni, Ag, and Al were calculated. The binding energies of impurity atoms with partial and stair-rod dislocations, as well as with jogs on them, were calculated. It is shown that the binding energy with partial dislocations is significantly lower than...

MECHANICAL AND BIODEGRADATION PROPERTIES OF CORNSTARCH-BASED BIOPLASTIC MATERIAL

A.B.D. Nandiyanto, M. Fiandini, R. Ragadhita, A. Sukmafitri, H. Salam & F. Triawan
The purpose of this study was to investigate mechanical and biodegradation properties of bioplastic from pure cornstarch (with no additional reinforcing components). The following fabrication procedure was done: (1) diluting cornstarch in water, (2) making homogeneous mixture of the diluted cornstarch, glycerol, and acetic acid by heating at less than 100ºC, (3) molding process, and (4) drying process to get a solid bioplastic. The present bioplastic had good biodegradability properties, degraded easily within 2-week soaking...

Simple Wigner-Langevin equation

Andrey L. Sanin
A new dynamical equation is derived by substituting the Schrödinger-LangevinKostin equation into the definition for the Wigner function, it can be called the quantumclassical Wigner-Langevin equation. The proposed equation contains partial derivatives for time and phase space variables of the Wigner function, its coefficients are spatial derivatives of potentials that take into account friction, white noise and external influence. The transition to the classical regime of motion is also discussed.

Development of a composite hatch cover

D. Mamchits, А. Nemov, A. Karandashev, D. Büchler, R. Vasilyev & M. Ignatiev
Two designs of a composite marine hatch cover were developed on the basis of the design of a steel one. One of the proposed designs features composite structure made by means of manual lay-up technology, and the other one is based on a truss composite structure which can be produced by rod winding process. Selection of the most rational materials and design parameters was carried out on the basis of finite element simulations and use...

Nuclear geometry: from hydrogen to boron

Alexander I. Melker
Possible ways of nuclear synthesis in the range from hydrogen to boron are studied. The geometric model of these nuclei is suggested. The basis for this model is the analogy between tetrahedral fullerene C4 and helium 2He4 . It is assumed that a nucleus of helium 2He4 has the form of a tetrahedron, where: 1) All the apices are equivalent and therefore they are protons, 2) Each neutron in a nucleus decomposes into a proton...

Influence of resonance Compton scattering in a magnetic field on rotation of the polarization plane of photons

Alexey I. Sery
The solution of the problem of the value of rotation of photon polarization plane in totally spin-polarized electron gas in quantizing magnetic field is obtained. The second order perturbation theory on electromagnetic coupling is considered using modified Gell-Mann– Goldberger–Thirring dispersion relationship and optical theorem. Approximate formula obtained by Fomin and Kholodov for resonance Compton scattering cross-section is used in calculation.

Isomeres and isotopes of carbon

Alexander I. Melker
The nuclear geometry has been developed by analogy with the fullerene geometry. On the base of this geometric approach, the structure of carbon isomers and isotopes, which can be obtained by means of nuclear synthesis, has been designed. The mechanisms of possible nuclear reaction are discussed. Carbon is an unusual element. It has four isomers of different symmetry: three-fold, six-fold and tetrahedral ones, two being stable and one halfstable. The isotopes of carbon inherit the...

Registration Year

  • 2020
    65

Resource Types

  • Text
    65

Affiliations

  • Peter the Great St. Petersburg Polytechnic University
    20
  • ITMO University
    4
  • Ioffe Institute
    4
  • Southern Federal University
    3
  • St Petersburg University
    3
  • Institute for Problems in Mechanics
    2
  • Lomonosov Moscow State University
    2
  • University of Patras
    2
  • Siberian State Industrial University
    2
  • Altai State Technical University
    2