Materials physics and mechanics

RAR RUS 1-19 University of Patras Apostolopoulos

Greece

University of Patras Drakakaki

Patrac, Greece

University of Ioannina Apostolopoulos

Ioannina, Greece

University of Ioannina Matikas

Ioannina, Greece

Peter the Great St. Petersburg Polytechnic University Rudskoy Andrey

St.Petersburg, Russia

T-5749-2017 6602123579 0000-0002-2102-1076 Peter the Great St. Petersburg Polytechnic University Kodzhaspirov Georgij kodjaspirov@spbstu.ru

St.Petersburg, Russia

Characteristic defects-corrosion damage and mechanical behavior of dual phase rebar The demands for constructions with high mechanical performance, located in seismic areas, expressed through EC2 and EC8- part3, were importantly satisfied mainly with the use of Tempcore dual phase steel bars. High mechanical performance of dual phase steel comes from the combination of the mechanical properties of each individual phase. However, several times have been reported problems concerning their structural cohesion. In the present study four different technical classes (DP) of reinforcing steel bars were used: B500c, B450c, B400c and B500b. SEM and EDX analyses were used, focusing not only on the internal defects regions of the materials (before and after corrosion), but also on the external areas affected by pitting corrosion. Moreover, in terms of the experimental procedure, mechanical tensile tests were conducted, on both corroded and non corroded reinforcing steel bar specimens and the pertinent results are analyzed. The conclusion from the present study is that both internal and external defects constitute a major problem for constructions, by diminishing their mechanical performance and resulting in their premature failure. dual phase rebar; dual phase steel; mechanical behavior; demands https://mpm.spbstu.ru/article/2017.52.1/ MPM130_01_apostolopoulos.pdf

RAR RUS 20-34 Ioffe Institute Pronin I.P.

St.Petersburg, Russia

P-4505-2016 7006034020 0000-0002-2973-8645 Institute of Problems of Mechanical Engineering RAS Kukushkin S.A. sergey,a.kukushkin@gmail.com

St.Petersburg, Russia

Scientific Research and Advanced Studies Center of Ensenada (CICESE) Spirin

Ensenada, B.C., México

Ioffe Institute Senkevich S.V.

St.Petersburg, Russia

Ioffe Institute Kaptelov E.Yu.

St.Petersburg, Russia

Herzen State Pedagogical University of Russia Dolgintsev

St.Petersburg, Russia

Herzen State Pedagogical University of Russia Pronin

St.Petersburg, Russia

National University of Science and Technology “MISiS” Kiselev D.A.

Moscow, Russia

Tver State University Sergeeva

Tver, Russia

Formation mechanisms and the orientation of self-polarization in PZT polycristalline thin films The influence of the pressure of the argon-oxygen gas mixture on the composition of Pb(Zr,Ti)O3 (PZT) films deposited by RF magnetron sputtering on the silicon substrate with a platinum layer has been studied. It was demonstrated that the change in the self-polarization vector is unambiguously associated with the variations of the concentration of lead in PZT films in relation to stoichiometric composition. It was found that at the high gas pressure (8 Pa) the entire volume of the thin PZT is crystallized in the perovskite phase, and with decreasing pressure to 2 Pa (and, consequently, with a decrease in lead content) the fraction of the perovskite phase in the film volume significantly decreases. For explanation of the reorientation of the polarization vector we have proposed the model which is based on mechanochemical phenomenon of the diffusion of lead atoms under the mechanical stresses caused by a distinction in the thermal expansion coefficients of the film and the substrate. Pb(Zr,Ti)O3 (PZT) films; RF magnetron sputtering; silicon substrate; pressure of the argon-oxygen gas; self-polarization vector https://mpm.spbstu.ru/article/2017.52.2/ MPM130_02_pronin.pdf

RAR RUS 35-39 Institute of Electrophysics UB RAS Kaygorodov

Ekaterinburg, Russia

Institute of Electrophysics UB RAS Mamaev

Ekaterinburg, Russia

Substrate influence on the mechanical properties of TiC/a-C coatings A new experimental approach of TiC/a-C coatings critical relative indentation depth determination is presented. The data comparison of similar coatings obtained by magnetron sputtering on WC-based and stainless steel substrates shows that TiC/a-C nanohardness is affected by the substrate at indentation depths larger than 10-13 % of the coating.s thickness. As for the friction coefficient, the soft substrate influences TiC/a-C coatings at the depths as small as 1 % of the coatings. thickness so this mechanical property is always influenced by the substrate. TiC/a-C coatings; mechanical properties https://mpm.spbstu.ru/article/2017.52.3/ MPM130_03_kaygorodov.pdf

RAR RUS 40-52 7003559440 0000-0003-2192-0386 Institute for Problems of Mechanical Engineering RAS Skiba Nikolai nikolay.skiba@gmail.com

St. Petersburg, Russia

Institute of Problems of Mechanical Engineering RAS I.A. Ovid’ko И.А.

St.Petersburg, Russia

113263 6701854079 0000-0001-9909-2950 Institute of Problems of Mechanical Engineering RAS Sheinerman Alexander

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Konakov

St.Petersburg, Russia

Micromechanisms of plastic deformation in nanotwinned materials A brief review of the theoretical models which describe specific plastic deformation mechanisms in ultrafine-grained materials with nanotwinned structure (nanotwinned materials) is presented. In particular, micromechanism of nanotwin widening and micromechanism of combined action of lattice dislocation slip and twin boundary migration in nanotwinned materials are considered. Dependence of the flow stress on the plastic strain in nanotwinned cooper (Cu) is calculated. Also, dependence of the yield stress on twin thickness in nanotwinned cooper (Cu) is theoretically described. Our theoretical results and their comparison with corresponding experimental data in the exemplary case of nanotwinned copper (Cu) are discussed. nanotwinned materials; micromechanisms of plastic deformation https://mpm.spbstu.ru/article/2017.52.4/ MPM130_04_skiba.pdf

RAR RUS 53-60 Mordovia State University N.P. Ogareva Yudin

Saransk, Russia

Mordovia State University N.P. Ogareva Ivlev

Saransk, Russia

Mordovia State University N.P. Ogareva Fomin

Saransk, Russia

Mordovia State University N.P. Ogareva Sigachyov

Saransk, Russia

Mechanical testing of CFRP with epoxy matrix The results of tensile test samples of composite material based on epoxy resin content of carbon fabric, including the cyclic change of stress until the destruction of the sample. Defines the limits of strength, the effective elastic modulus, hysteresis loss. It was shown that the dependence of the module against mechanical stresses determined by the matrix, whereas the numerical value of the strength characteristics mostly depend on the filler. Mechanical cycling leads to a stabilization of the deformation characteristics of the material. epoxy resin; carbon; creep; mechanical properties; deformation https://mpm.spbstu.ru/article/2017.52.5/ MPM130_05_yudin.pdf

RAR RUS 61-67 Mordovia State University N.P. Ogareva Ivlev

Saransk, Russia

Mordovia State University N.P. Ogareva Sigachyov

Saransk, Russia

Mordovia State University N.P. Ogareva Fomin

Saransk, Russia

Mordovia State University N.P. Ogareva Yudin

Saransk, Russia

Creep of solid epoxy resin Were tested for creep of the cured polyester resin PN-1, depending on the mechanical stress (2,6 ÷ 24 MPa) and temperature (15 ÷ 45 °C). In all cases, the dependence of the strain on the time was characteristic of the low temperature (logarithmic) creep. It is shown that for the interpretation of experimental data is possible using the model developed for crystalline solids. The estimation of the size of "elementary volume", which can be subjected to continuous deformation regardless of the deformation of the neighboring elementary volume. solid epoxy resin; creep https://mpm.spbstu.ru/article/2017.52.6/ MPM130_06_ivlev.pdf

RAR RUS 68-74 Altai State Technical University Poletaev Gennady M.

Barnaul, Russia

Altai State Technical University Novoselova

Barnaul, Russia

Siberian State Industrial University Zorya

Novokuznetsk, Russia

I.I. Polzunov Altai State Technical University Starostenkov

Barnaul, Russia

Diffusion radius of triple junctions of tilt boundaries in Ni In the present study it was evaluated the diffusion radius of triple junctions of and tilt boundaries in Ni, obtained by crystallization, depending on the content of free volume. It is shown that diffusion in the area of triple junctions containing excess free volume proceeds much more intense than in the case when the additional vacancies were not introduced in the calculation block. In the boundaries and junctions formed by them during crystallization the free volume dissipated much more efficiently than in the junctions formed by the boundaries. For this reason the diffusion radius of the triple junction of boundaries at the introduction of 2 % conditional vacancies (about 3.5 Å) less than the radius of the junction of boundaries (4-5 Å). molecular dynamics; triple junction; grain boundary; tilt boundary; free volume; diffusion; diffusion canal; radius of triple junction https://mpm.spbstu.ru/article/2017.52.7/ MPM130_07_poletaev.pdf

RAR RUS 75-85 Institute Silicate Chemistry of Russian Academy of Science Konakov V.G.

St.Petersburg, Russia

Scientific and Technical Center “Glass and Ceramics” Archakov

St.Petersburg, Russia

Institute Silicate Chemistry of Russian Academy of Science Solovyeva E.N.

St.Petersburg, Russia

Scientific and Technical Center “Glass and Ceramics” Golubev

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Orlov

St.Petersburg, Russia

Synthesis of gum-metal-graphene nanocomposite For the first time in science of metal-matrix composite materials, "Gum-metalgraphene" nanocomposite is synthesized which has a Gum metal (Ti-Nb-Ta-Zr-O alloy) matrix containing graphene nanoinclusions. To do so, we created a novel method to synthesize Gum metal and "Gum-metal-graphene" nanocomposite. In the latter case, micromechanical splitting of thermo-exfoliated graphite is used as graphene source. With Xray analysis, we demonstrated that the phase compositions of Gum metal specimens and the nanocomposite matrix are identical to one of typical Gum metal compositions reported in literature. "Gum-metal-graphene" nanocomposite; synthesis https://mpm.spbstu.ru/article/2017.52.8/ MPM130_08_konakov.pdf

RAR RUS 86-92 Institute for Problems of Mechanical Engineering of the RAS Semenov

St.Petersburg, Russia

Finite-element models of mechanical characteristics of "(nano)metal-graphene" nanocomposites To evaluate the effect of graphene inclusions on deformation characteristics of nanocomposite "metal-graphene" the finite element analysis of representative volume deformation followed by homogenization of the mechanical properties deformation is performed and the dependence of effective modules and plastic flow on the concentration of graphene inclusions is studied. It is shown that the influence of inclusions on the modulus of elasticity and plasticity limit of the nanocomposite is not significant. Graphene inclusions effect on strength and fracture toughness of the composite "(nano) metal-graphene". The results of finite-element simulations indicate that in the nanocomposite a decrease in stress concentration in vicinity of the crack tip is observed when approaching the crack tip to the graphene inclusion enable. composite; metal-graphene; strength; fracture; cracks https://mpm.spbstu.ru/article/2017.52.9/ MPM130_09_semenov.pdf

RAR RUS 93-101 Institute Silicate Chemistry of Russian Academy of Science Konakov V.G.

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Arutyunyan A.R.

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Lomakin

St.Petersburg, Russia

Institute Silicate Chemistry of Russian Academy of Science Solovyeva E.N.

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Kurapova

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Novik

St.Petersburg, Russia

Scientific and Technical Center “Glass and Ceramics” Archakov

St.Petersburg, Russia

Institute of Problems of Mechanical Engineering RAS I.A. Ovid’ko И.А.

St.Petersburg, Russia

Investigation of mechanical properties of nickel and "Ni-YSZ" nanocomposite at tension, compression and fatigue tests In this paper, we present experimental data on synthesis and investigation of the mechanical properties of bulk nickel and bulk "nickel - 8 mol.% Y2O3-92 mol.% ZrO2" nanocomposite with a nickel matrix containing crystalline ceramic nanoparticles. In terms of wt.%, this nanocomposite (hereinafter called Ni-YSZ nanocomposite) contains 1 wt.% of ceramic nanoparticles. The Ni and Ni-YSZ nanocomposite specimens were fabricated by powder metallurgy technique with successive annealing at 1250 °C. In tension and compression tests, we revealed stress-strain dependences showing degradation of strength and ductility exhibited by Ni-YSZ nanocomposite, as compared to those of pure Ni fabricated in the same conditions. The fatigue tests of the specimens were performed in the symmetric tensioncompression regime based on 107 cycles. The fatigue limits were identified. The specimen fabricated from pure Ni powder showed the fatigue limit of 110 MPa, whereas Ni-YSZ composite exhibited the fatigue limit of 50 MPa. Thus, the insertion of ceramic nanoparticles into Ni matrix gives rise to more than two times decrease of the fatigue limit, as compared to pure Ni. The fractography of fatigue fracture surfaces was examined by scanning electron microscopy. In both materials tested, three stages of the fatigue crack distribution are observed which are the crack initiation, stable crack growth and unstable crack growth stages. Both materials contain the significant amounts of pores, and pore merging is observed at the unstable crack growth stage. nickel; nanocomposite "Ni-YSZ"; tension; compression; fatigue https://mpm.spbstu.ru/article/2017.52.10/ MPM130_10_konakov.pdf