30 Works

Optimization of powder metallurgy process parameters to enhance the mechanical properties of AZ91 magnesium alloy

Naveen Kumar & Ajaya Bharti
In the present work, optimization of powder metallurgy process parameters, i.e., compaction pressure, sintering time, and sintering temperature, for magnesium alloy AZ91 is done using Taguchi Design of Experiment and ANOVA techniques. Regression equation for determining ultimate compressive stress and hardness of AZ91 Magnesium alloy was formulated and validated experimentally. Out of the nine sets of parameters present in the current design, H8 (450 MPa compaction pressure, 450° sintering temperature, and 60 minutes sintering time)...

On the problem of evaluating the behavior of multicomponent materials in mixed boundary conditions in contact problems

Vladimir Babeshko, O.V. Evdokimova & Olga Babeshko
For the purposes of evaluating the behavior of multicomponent materials under operating conditions, the paper for the first time constructs in general an exact solution of systems of Wiener-Hopf integral equations of arbitrary order. Systems of these equations arise in mixed problems of continuum mechanics for multicomponent materials of complex rheology. The cases of mixed boundary value problems are considered under the assumption that there is a change of boundary conditions on the inner or...

First-principles study of anisotropic thermal conductivity of GaN, AlN, and Al0.5Ga0.5N

DZMITRY HVAZDOUSKI, Maryia Baranava & Viktor Stempitsky
The thermal stability of devices based on GaN, AlN, and Al0.5Ga0.5N semiconductors is a critical property for efficient and reliable operation. The thermal conductivity of these materials has anisotropic nature. We proposed an approach for calculating the anisotropic thermal conductivity based on harmonic and anharmonic interatomic force constants of a lattice. The thermal-conductivity coefficient of GaN, AlN, and Al0.5Ga0.5N in the [100], [001], and [111] directions were calculated using ab initio methods by solving the...

An out-of-plane oscillating beam nanoresonator with ultrahigh intrinsic quality factor

Manh Hoang Chu, Duong Nguyen Van & Dang Van Hieu
An out-of-plane oscillating beam nanoresonator with the ultrahigh intrinsic quality factor based on the motion transformation mechanism from torsion into rotation is reported. The nanoresonator is composed of two resonant beams which are mechanically coupled through two spring beams oscillating in an out-of-phase torsional mode. The out-of-phase torsional oscillation of the two spring beams forms a stationary point in the middle of a supporting beam, which minimizes anchor loss. The low thermoelastic damping (TED) in...

Seismic behavior of heritage building with isotropic and orthotropic material properties: a comparative analysis

Kamran , shakeel ahmad & REHAN A KHAN
Restoration and retrofitting of heritage buildings is a complex analysis. In actual practice, building materials of heritage masonry buildings are anisotropic. However, in practice, these building materials had been considered isotropic to optimize the analysis. The present study is a comparative analysis of these two approaches. A heritage school building in northern India underlying seismic zone IV has been considered for the analysis. The seismic performance analysis of the buildings has been carried out through...

Influence of temperature and load on mechanical properties of unirradiated and irradiated plexiglass

Anatoly Kupchishin, Buvkhan Taipova, Marat N. Niyazov, Daniya C. Utepova, Viktor Lisitsyn & Boris A. Tronin
Investigations of the mechanical, properties of unirradiated and irradiated plexiglass of various types have been carried out when tested for the flat straight bend. Exposure to temperature and radiation significantly affects the properties of the material. As a result of the research, the dependences of deformation on stress, length, and width of the specimens were obtained. The experimental curves are satisfactorily described by a linear model.

Non-equilibrium phonon gas in a chalcogenide semiconductor with exponential temperature dependence of conductivity

Karim Mynbaev & N.V. Sovtus
The distribution function for a phonon gas in the non-equilibrium case of current crowding in a chalcogenide glassy semiconductor is considered. The approximate internal energy of the gas and its heat capacity is calculated. The change in the heat capacity caused by phase changes, which according to the results of the numerical calculations, are similar to the second-order phase transition, is analyzed. The law of temperature variation with time is calculated for a homogeneous current...

Study numerical and experimental of stress concentration factor on isotropic plate with hole

M.N. Misbah, Rizky Chandra Ariesta, T. Yulianto, Dony Setyawan & W.H.A. Putra
The stress concentration factor (SCF) can lead to the failure of ship construction. That problem can occur with hotspot stress expansion in the local area because of the acting load and structural details shapes. However, there is no method for the asses of structure design failure in the minor openings such as a dry hole and scallop dimension. Furthermore, the research aims for evaluating stress concentration performed using the diameter and width (d/W) ratio. The...

Influence of Ni-Al interphase boundary orientation on the interdiffusion rate at temperatures above aluminum melting point: a molecular dynamics study

Gennady Poletaev & Роман Ракитин
The influence of the orientation of Ni-Al interphase boundary relative to the nickel crystal lattice on the intensity of interdiffusion at temperatures above the melting temperature of aluminum was studied by the method of molecular dynamics. It was observed that the boundary between the crystalline and liquid phases was, in fact, shifted by two or three atomic planes into the aluminum phase – a thin layer of aluminum near the boundary retained a crystalline structure...

Effect of Si+ ion irradiation of α-Ga2O3 epitaxial layers on their hydrogen sensitivity

Nikita Yakovlev, Aleksei Almaev, Pavel Butenko, Alexey Mikhaylov, Aleksey Pechnikov, S.I. Stepanov, Roman Timashov, Andrew Chikiryaka & Vladimir Nikolaev
The effect of Si+ ion irradiation of α-Ga2O3 at doses of 8·1012 cm-2, 8·1014 cm-2, and energy of 100 keV on the gas-sensitive properties has been studied. It is shown that irradiation of α-Ga2O3 layer grown by halide vapor phase epitaxy with implanted Si+ ions allows effective control of its sensitivity to H2, response, and recovery times, as well as varying the operating temperatures. The maximum sensitivity to H2 occurred for samples with Si+ ion...

Emergence of topological defects in a bilayer of multiwalled carbon nanotubes irradiated by gamma-rays

Halina Grushevskaya, A.I. Timoshchenko & I.V. Lipnevich
We have studied gamma-ray scattering on rolled graphene atomic layers of high-ordered multiwalled-carbon-nanotubes which organized a bilayer. Radiation high-energy topological defects of a type of pair "vortex-antivortex" in electron and hole densities have been revealed. We suppose that the fluxes of the vortex-antivortex pairs are produced by gamma-quanta in the graphene plane.

Analysis of the conditions of crack nucleation during lattice dislocations transition through grain boundary

Vladimir Perevezentsev, Sergey Kirikov & Nikolai Zolotorevsky
The formation of deformation facets at high-angle grain boundaries during their interaction with lattice dislocation pile-ups is accompanied by the appearance of wedge disclination dipoles disposed on the plane of the facets. Their elastic energy increases as the dislocations of pile-up penetrate the grain boundary and the deformation facet lengthens. A possibility was considered for the relaxation of elastic energy of the disclination dipole and the pile-up stored in the vicinity of the facet. A...

Modelling of composite materials with thermoplastic matrices, carbon fibres, and nanoparticles

Aleksandra Romashkina, Mikhail Khovaiko & Alexander Nemov
This paper reports a study regarding the modelling of the mechanical behaviour of a thermoplastic matrix/carbon fibre reinforced composite. It has been shown that the multiscale modelling approach, based on the submodelling technique, describes the material behaviour accurately enough. To simulate non-ideal adhesion, a series of composite material models were developed, the adhesion being modelled by introducing contact elements along with various parts of the fibre-binder interface surface. The introduction of contact interaction only affected...

Deformation and mechanical stresses in a magnet with thin-walled quasi-force-free winding

German Shneerson, Artem Khlybov, Andrei Belov, A.P. Nenashev, A.A. Parfentiev & S.A. Shimanskiy
The factors leading to an increase in the mechanical stress in the winding of solenoids are considered on the example of a thin-walled magnet with a multi-turn quasi-force-free winding. This example is compared with an ideal system in the form of a solenoid with unlimited length and continuous current distribution. A method for measuring submicron-sized dynamic deformations of the winding in a pulsed field has been developed and verified by comparing experiment results and calculations....

Preparation and characterization of undoped and antimony doped tin oxide thin films synthesized by spray pyrolysis

Halima HABIEB & Nasr-Eddine HAMDADOU
Undoped and antimony doped tin oxide thin films (SnO2 :Sb) have been deposited by the spray pyrolysis method on glass substrates heated at 350°C, with various doping concentrations 0 (undoped), 1 at.%, 3 at.%, and 5 at.%. The influence of annealing temperature and various Sb doping rates on the structural, morphological and optical properties have been investigated, using grazing incidence X-ray diffraction (GIXRD), profilometry, atomic force microscopy (AFM), UV-Visible spectrophotometry and photoluminescence measurements (PL). GIXRD...

Calculation of the stress level in modeling the inter-dislocation interaction of aluminum bronze

Anton Nikonov, Artem Bibko & Dmitry Lychagin
The behavior of a polycrystal during deformation depends on the deformation of its constituent grains, their boundaries, and the degree of interaction. In this case, the deformation of a single grain is determined by its orientation and morphology. An urgent task is to estimate the stress level for individual grains of a polycrystalline aggregate of aluminum bronze. This problem can be solved by molecular dynamics simulation of crystallites with different crystallographic and geometric characteristics. Based...

The nanofluids' viscosity prediction through particle-media interaction layer

Vyacheslav Syzrantsev, Vyacheslav Syzrantsev, Alexey Zavjalov & Vyacheslav Syzrantsev
This work aims to draw a more fundamental understanding of the rheology of nanofluids and the interpretation of the discrepancy in the literature. The rheology of dispersions based on SiO2 and Al2O3 nanoparticles obtained by four different methods is experimentally investigated in the Newtonian range. It is shown that the viscosity dependence on concentration for nanofluids with particles of different synthesis methods has different values. The parameter of the associated liquid layer model describing the...

Photoelectrochemical degradation of methylene blue with nano TiO under high potential bias

Taicheng An, Guiying Li, Ya Xiong, Xihai Zhu, Hengtai Xing & Guoguang Liu
In this work, photoelectrocatalytic degradation of wastewater containing methylene blue (MB) was investigated using a novel photoelectrochemical reactor – a three dimensional electrodes-photocatalytic oxidation reactor in which nano TiO2 was used as photocatalyst. The experimental results are assessed in the terms of decolorization and Chemical Oxygen Demanded (COD) removal efficiencies. The experimental results showed that the three dimensional electrodephotocatalytic reactor could effectively destroy MB within a reaction time of 30 min. It was found that...

Maxwell electrodynamics in media, geometry effect on constitutive relations

Nina Krylova, Elena Ovsiyuk, Alina Ivashkevich & Viktor Redkov
. The problem of constitutive relations in Maxwell electrodynamics, their possible form and role in physical manifestation of electromagnetic fields, its behavior under the motion of the reference frame and its connection with Special Relativity theory, interplay between electrodynamics constitutive relations and gravity theory, and so on, has a long history. The main accent in our treatment is the known possibility to simulate material media by geometrical methods. This review includes the following items: Riemannian...

Modeling of PKA energy spectra and the concentration of vacancy clusters in materials irradiated with light ions

Natalia A. Voronova, Alexander A. Kupchishin, Anatoly Kupchishin & Tatiana A. Shmygaleva
The work was carried out within the framework of the cascade-probabilistic method, the essence of which is to obtain and further apply cascade-probabilistic functions. The obtained models make it possible to trace the entire process in development and in the future can be used in industry to obtain materials with predetermined characteristics. The results of the obtained studies can also be used by specialists in the field of solid-state radiation physics, in сosmophysics. The cascade-probability...

Silicon carbide membranes for micro-electro-mechanical-systems based CMUT with influence factors

Moumita Pal, N. P. Maity & Reshmi Maity
An analytical model is developed for evaluating the characteristic parameters of silicon carbide (SiC) based capacitive micromachined ultrasonic transducer (CMUT) under the effect of a high-k dielectric insulation layer. The performance of parallel plate structured CMUT is investigated by considering various widths of the insulation layer, membrane thickness, diameter, and bias followed by validation of results using finite element method (FEM) simulation. Consideration of the fringing effect results in noticeable improvements in device capacitance. This...

Magnetic properties of low-dimensional MAX3 (M=Cr, A=Ge, Si and X=S, Se, Te) systems

Maryia Baranava & Viktor Stempitsky
The article presents the results of a magnetism study in quasi-two-dimensional MAX3 (M=Cr, A=Ge, Si and X=S, Se, Te) systems. We calculated the microscopic magnetic parameters using quantum mechanical methods and showed that MAX3 can have a high spin polarization. The easy magnetization axis lies normal to the layer plane. The main magnetic order of the CrGeSe3, CrGeTe3, CrSiSe3, and CrSiTe3 atomic systems is ferromagnetism. CrGeS3 and CrSiS3 exhibit antiferromagnetism. The low energy stability of...

Maxwell electrodynamics, complex rotation group, media

Alina Ivashkevich, Elena Ovsiyuk, Vasiliy Kisel & Viktor Redkov
Our treatment will be with definite accents: the main attention is given to classical electrodynamics in material media, focusing on the structure of Minkowski constitutive relations, matrix complex form of Maxwell theory in the form of Riemann–Silberstein–Majorana–Oppenheimer, and the theory of complex rotation group , isomorphic to the Lorentz group. This review includes the topics: introduction; matrix complex form of Maxwell theory in a vacuum; modified Lorentz symmetry in electrodynamics; Minkowski electrodynamics in moving bodies;...

Nucleation and growth of fullerenes and nanotubes having five-fold symmetry

Alexander I. Melker, Maria Krupina & Alexandra Matvienko
We have studied possible ways of generating and growing the fullerenes having five-fold symmetry. Beginning with cyclopentane C5H10 and clusters C5C5, we obtained elementary fullerenes C10 and mini-fullerenes C20, and then we produced the fullerenes from C20 to C70, perfect (basic) and imperfect, as well as nanotubes. The basic fullerenes C20, C30, C40, C50, C60, and C70 have the ordinary five-fold symmetry, the intermediate ones having no such symmetry. Their imperfection is connected with extra...

On resonant scattering states in graphene circular quantum dots

Halina Grushevskaya & George Krylov
Due to the effect of Klein tunneling, two-dimensional graphene quantum dots do not possess genuine bound states but quasi-bound (resonant tunneling) states only. We discuss in detail the attempt to describe these states within the framework of the Dirac pseudo-fermion model for circular dots. We demonstrate explicitly that introduced earlier the so-called "resonance condition" corresponds to the inconsistent system of linear equations obtained from matching conditions on the boundary of the quantum dot when one...

Registration Year

  • 2022
    30

Resource Types

  • Journal Article
    30

Affiliations

  • Ioffe Institute
    2
  • Peter the Great St. Petersburg Polytechnic University
    1
  • Perm National Research Polytechnic University
    1