Materials physics and mechanics

RAR RUS 265-271 ITMO Univesity V.G. Dubrovskii

St.Petersburg, Russia

Ioffe Institute Sokolovskii

St.Petersburg, Russia

Evolution of the droplet shape in the vapor-liquid-solid growth of III-V nanowires under varying material fluxes We present a model for the time evolution of the shape of a droplet catalyzing the vapor-liquid-solid growth of III-V semiconductor nanowires under varying group III or group V fluxes. Under the assumption of a constant radius of the nanowire top, the model gives the time dependence of the droplet contact angle. These results can be used for the fine tuning of the droplet shape, which affects the preferred crystal phase (zincblende or wurtzite) of III-V nanowires. 10.18720/MPM.4232019_1 Catalyst droplet vapor-liquid-solid growth III-V nanowires https://mpm.spbstu.ru/article/2019.70.1/ MPM342_01_dubrovskii.pdf

RAR RUS 272-279 Tokushima University Yamaguchi

Tokushima, Japan

Tokushima University Koinkar

Tokushima, Japan

Tokushima University Furube

Tokushima, Japan

Study of heat dissipating material using boron nitride fabricated by laser ablation More research interest is developing rapidly on two dimensional (2D) materials owing to their excellent electro-optic properties to develop next generation of electronics and highly functional devices. Among well-known and widely used 2D materials, boron nitride (BN) is an electrical insulator with a band gap of 5.5 eV, and attests high chemical stability, outstanding mechanical properties, and high thermal conductivity. Accordingly, BN is considered as a promising candidate to improve the heat dissipation material performance. In this study, the cooling rate of composite materials of poly methyl methacrylate (PMMA), hexagonal boron nitride (h-BN) and gold nanoparticles was investigated using femtosecond transient absorption spectroscopy. The main objective of this study is to prepare the flexible BN-PMMA films could have a significant impact on heat dissipation to enhance the performance of electronics devices. BN nanostructures were prepared by nanosecond laser ablation in acetone. The laser ablation was carried out at room temperature with laser ablation time of 120 min. The SEM images of bulk BN and laser ablated BN were obtained for structural and surface morphological characterization. Gold colloidal solution was prepared using gold nano-particles with chloroauric acid and distilled water. For the preparation of composite film, PMMA was dissolved in acetone solvent and then mixed with BN and gold colloid solution. The prepared composite films were examined for cooling rate of photoexcited gold nanoparticles using femtosecond transient absorption spectroscopy. It is found that the lifetime is shorter for composite films with Au and high BN content. 10.18720/MPM.4232019_2 boron nitride laser ablation X-ray diffraction raman spectroscopy scanning electron microscopy cooling process transient absorption spectroscopy (TAS) https://mpm.spbstu.ru/article/2019.70.2/ MPM342_02_yamaguchi.pdf

RAR RUS 280-287 Government Institute of Science Atram

India

Government Institute of Science Sonawane

India

Comparative study of adsorption of ozone molecule on pristine and Si doped Single Wall Carbon Nanotube by density functional theory 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 eV to 0.54 eV. The ozone gas molecule is physisorbed with binding energy 0.431eV and minute charge transfer of 0.013 e from pure carbon nanotube, consistent with the strong oxidizing nature of ozone. The binding energy and charge transfer indicate that the ozone adsorption on pure carbon nanotube is gentle and reversible. However, when ozone adsorbs on silicon doped carbon nanotube, a strong chemisorption occurs, leading to relevant structural relaxations and to the formation of a Si-O σ bond with binding energy 3.902 eV and charge transfer of 0.252 e. The band structure and density of states shows that the occupancy state in valence band near Fermi energy is completely altered due to ozone adsorption. The charge density analysis also shows formation of sigma bond between silicon and oxygen atoms. The charge density iso-surface shows the oxidation of silicon atom and dissociation of ozone molecule into silicon - oxide and releasing of oxygen molecule. 10.18720/MPM.4232019_3 CNT Si-CNT DFT ozone adsorption https://mpm.spbstu.ru/article/2019.70.3/ MPM342_03_atram.pdf

RAR RUS 288-295 National Institute of Technology Reddy

India

National Institute of Technology Maity

India

National Institute of Technology Pandey

India

Effect of warm rolling on microstructure, porosity, and hardness of a spray-formed LM25 aluminum alloy The LM25 aluminum alloy was obtained using the spray deposition method at an optimum pressure of approximately 10 bar, a deposition distance of approximately 41 cm. and an inclination angle of 0º. The central portion of the spray deposit was warm rolled to obtain various thickness reductions, i.e., 0%, 20%, 40%, 60%, and 80% at 100ºC; it was found that the number of pores decreased as the thickness reduction increased. It was observed that the fine microstructure and secondary phase in the samples with a larger percentage of thickness reduction was due to the expediting cooling and freezing rate of the molten metal. The porosity and mechanical properties were better in the spray deposited and warmed rolled LM 25 substrate than the cast LM25 alloy. 10.18720/MPM.4232019_4 spray forming warm rolling microstructure porosity hardness https://mpm.spbstu.ru/article/2019.70.4/ MPM342_04_reddy.pdf

RAR RUS 296-310 Peter the Great St. Petersburg Polytechnic University Savikovskii

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Semenov Artem

St.Petersburg, Russia

Polzunov Central Boiler and Turbine Institute, Getsov

St.Petersburg, Russia

Coupled thermo-electro-mechanical modeling of thermal fatigue of single-crystal corset samples The possibilities of predicting thermal fatigue durability for single crystal on the base of coupled thermo-electro-mechanical finite-element modeling with using of deformational criterion and microstructural models of inelastic deformation are investigated. Results of thermal and stress-strain state simulations of single-crystal corset specimens under cyclic electric heating and cooling are presented and discussed. Comparison of computational results with experimental data for various single-crystal nickel-based superalloys demonstrates a good accuracy in the prediction of the number of cycles for the macrocrack initiation. The influence of maximum / minimum values of temperature in cycle and delay duration on the number of cycles for the macrocrack initiation are analyzed. The simplified analytic approximation for thermal fatigue durability curves is proposed. 10.18720/MPM.4232019_5 thermal fatigue single-crystal nickel based superalloy deformation criterion corset sample thermo-electric problem finite element modeling https://mpm.spbstu.ru/article/2019.70.5/ MPM342_05_savikovskii.pdf

RAR RUS 311-322 CIAM Vasilyev

Moscow, Russia

BMSTU Selivanov

Moscow, Russia

Numerical method of single-crystal turbine blade static strength estimation taking into account plasticity and creep effects 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 tension under conditions of short-term and long-term loading. The possibility of using linear interpolation to determine the characteristics of plasticity and creep for intermediate CO has been confirmed. An example is given of using the developed calculation method in the Finite Element Analysis Software CalculiX using the model blade as an example. 10.18720/MPM.4232019_6 single-crystal crystallographic orientation anisotropy stress-strain state plasticity creep https://mpm.spbstu.ru/article/2019.70.6/ MPM342_06_vasilyev.pdf

RAR RUS 323-329 Universitas Pendidikan Indonesia Nandiyanto

Bandung, Indonesia

Sampoerna University Triawan

Indonesia

Tokyo Institute of Technology R. Firly

Tokyo, Japan

Universitas Pendidikan Indonesia Abdullah

Indonesia

Tokyo Institute of Technology Aono

Tokyo, Japan

Tokyo Institute of Technology, Inaba

Tokyo, Japan

Tokyo Institute of Technology, Kishimoto

Tokyo, Japan

Identification of micro-mechanical characteristics of monoclinic tungsten trioxide microparticles by nanoindentation technique Tungsten trioxide (WO3) has excellent mechanical properties, making them to be applied in various applications. However, researches on the mechanical properties of WO3 in the micrometer scale are limited. Here, the purpose of this study was to demonstrate nanoindentation technique in an attempt to study the micro-mechanical characteristics of monoclinic WO3 microparticles that were previously synthesized using a direct heat treatment of ammonium tungstate pentahydrate powder at a temperature of 800°C. The experiment comprises a measurement by load controlled nanoindentation test on the particle sample to obtain force and displacement relationship. The results exhibited variability on the forcedisplacement curves for similar applied load. This could be due to the micro-mechanical effects generated by the existence of inclusions, precipitates, and oxides inside the micron WO3 particles. The present study demonstrates the importance of understanding the micromechanical characteristics of WO3 for clarifying the inhomogeneity effects on its macromechanical properties. 10.18720/MPM.4232019_7 tungsten trioxide micro-mechanical characteristics nanoindentation porous material https://mpm.spbstu.ru/article/2019.70.7/ MPM342_07_nandiyanto.pdf

RAR RUS 330-339 Institute of Computational Modeling SB RAS Sadovskii

Krasnoyarsk, Russia

Institute of Computational Modeling SB RAS Sadovskaya

Krasnoyarsk, Russia

Supercomputing analysis of fan-shaped waves in the Earth's crust at the depth of seismic activity 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. 10.18720/MPM.4232019_8 shear rupture extremely high speed Tarasov's fan-shaped mechanism edge dislocation dynamics elasticity high-performance computations https://mpm.spbstu.ru/article/2019.70.8/ MPM342_08_sadovskii.pdf

RAR RUS 340-350 Peter the Great St. Petersburg Polytechnic University Leontiev

St.Petersburg, Russia

Ulyanovsk State University Efremenkov

Ulyanovsk, Russia

Finite element modeling and investigation of elastic homogeneous and heterogeneous materials A novel finite element (FE) connected with orthogonal finite functions (OFF) was developed for ANSYS software and was tested. The FE is proposed for modeling and investigation of stress-strain states of homogeneous and heterogeneous elastic materials. The efficiency of the developed FE is demonstrated using the examples of plane problems of elasticity. The accuracy of this FE was found to be higher than that of the classical FE of ANSYS. Moreover, the developed FE was proved to require less computational time, and this difference in computational time increases with the increasing number of FE in the model. 10.18720/MPM.4232019_9 homogeneous and heterogeneous materials finite element methods orthogonal finite functions shape functions https://mpm.spbstu.ru/article/2019.70.9/ MPM342_09_leontiev.pdf

RAR RUS 351-358 Peter the Great St. Petersburg Polytechnic University Kalyuzhnyuk

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Lapin

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Murachev

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Osokina

St.Petersburg, Russia

Gazpromneft Science & Technology Centre Sevostianov

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Tsvetkov

St.Petersburg, Russia

Neural networks and data-driven surrogate models for simulation of steady-state fracture growth 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 modelling of hydraulic fracturing. The solution obtained allows to predict the aspect ratio value quickly, and thus, to evaluate the volum 10.18720/MPM.4232019_10 neural networks surrogate model hydraulic fracturing crack https://mpm.spbstu.ru/article/2019.70.10/ MPM342_10_kalyuzhnyuk.pdf

RAR RUS 359-366 National Research Lobachevsky State University of Nizhni Novgorod Volkov

Nizhny Novgorod, Russia

Lobachevsky State University of Nizhni Novgorod Igumnov

Nizhni Novgorod, Russia

Lobachevsky State University of Nizhni Novgorod Shishulin

Nizhny Novgorod, Russia

Modeling plastic deformation and damage accumulation processes in structural steels under block non-symmetric low-cycle loading To assess the reliability and the scope of applicability of the defining relations of mechanics of damaged media (MDM) [1,2], plastic deformation and damage accumulation processes in a number of structural steels under low-cycle loading have been numerically investigated, and the obtained numerical results have been compared with the data from fullscale experiments. It is shown that the introduced MDM model qualitatively and quantitatively describes the main effects of plastic deformation and damage accumulation processes in structural alloys under block-type non-stationary non-symmetric low-cycle loading. 10.18720/MPM.4232019_11 low-cycle fatigue plastic deformation damage degree block-type loading mechanics of damaged media modeling numerical and full-scale experiment https://mpm.spbstu.ru/article/2019.70.11/ MPM342_11_volkov.pdf

RAR RUS 367-372 Universitas Pendidikan Indonesia Sukrawan

Indonesia

Universitas Pendidikan Indonesia Hamdani

Bandung, Indonesia

Universitas Pendidikan Indonesia Mardani

Indonesia

Effect of bamboo weight faction on mechanical properties in non-asbestos composite of motorcycle brake pad 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% of bamboo fiber, 30% of MgO, and 30% of epoxy resin), composite 2 (50% of bamboo fiber, 25% of MgO, and 25% of epoxy resin), and composite 3 (60% of bamboo fiber, 20% of MgO, and 20% of epoxy resin). Tests for mechanical properties were carried out using a standard analysis, such as wear rate using ASTM D3702-94 standard, hardness test using ASTM D 785-03 type R, heat resistance using 2300 testing temperature, and composite brake lifetime analysis. The results showed that the composition of bamboo brought great influences on the mechanical properties. The best specimen had a wear rate of 0.9612.10-8 g/mm2 .s, hardness of 91.8 HRR, and heat resistance at 280°C with a duration of 810 days. It is expected that the use of composite brake pads made from bamboo fiber can replace brake pads made from asbestos, which is healthier and safer to use. 10.18720/MPM.4232019_12 asbestosis bamboo fiber composite material brake pad https://mpm.spbstu.ru/article/2019.70.12/ MPM342_12_sukrawan.pdf