Щодо розрахунку деформацій зсуву в призматичних стержнях із полімерних матеріалів за умов розтягу з крученням

The process of creep of prismatic rods made of linear-viscoelastic polymeric materials under combined loading is considered. Defining equations that determine the relationship between strains, stresses and time are given in the form of a superposition of shear and bulk strain. The object of study is prismatic bars made of fiberglass ST-1. The area of linearity of the model is substantiated on the basis of the hypothesis of the existence of the creep function, which is built on the yield curves, a single diagram of long-term deformation and the statistical value of the quantile of statistics. The region of linear-elastic deformation is recognized based on the fulfillment of the condition of existence of a single creep function. The defining equations of the model contain a set of functions and coefficients determined from the basic experiments. On the basis of the relations between the kernels of the one-dimensional stress state, the parameters of the kernels under the condition of a complex stress state are determined. The linearity of viscoelastic properties is given by the Boltzmann-Voltaire equations. The fractional-exponential kernels of heredity are chosen as the kernels of heredity. The obtained values of the core parameters are used to calculate the creep deformations of prismatic bars made of ST-1 fiberglass under conditions of simultaneous tensile tension. Pages of the article in the issue: 115 - 118 Language of the article: UkrainianРозглядається процес повзучості призматичних стержнів з лінійно-в’язкопружних полімерних матеріалів за умов комбінованого навантаження. Визначальні рівняння, що описують залежність між деформаціями, напруженнями і часом, задаються у вигляді суперпозиції зсувної і об’ємної деформації. Об’єктом дослідження являються призматичні стержні зі склопластику СТ-1. Обґрунтовується область лінійності моделі, виходячи з гіпотези існування функції повзучості, побудованої по кривим податливості, єдиної діаграми довготривалого деформування і статистичного значення квантиля статистики. Визначається область лінійно-пружного деформування, виходячи з виконання умови існування єдиної функції повзучості. Визначальні рівняння моделі містять набір функцій і коефіцієнтів, що знаходяться з базових експериментів. На підставі співвідношень між ядрами одновимірного напруженого стану визначаються параметри ядер за умови складного напруженого стану. Лінійність в'язкопружних властивостей задається рівняннями Больцмана-Вольтера з дробово-експоненціальним ядром спадковості. Отримані значення параметрів ядер використовуються для розрахунку деформацій повзучості призматичних стержнів зі склоапластика СТ-1 за умов одночасної дії розтягу з крученням

Performance-based seismic evaluation methods for the estimation of inelastic deformation demands

The article presents experimental research and comparison of two performance-based seismic evaluation methods: Nonlinear static procedure (NSP)/pushover analysis (PoA) and nonlinear time history analysis. It is established that nonlinear static procedure is good enough for prediction of plastic hinges localization, but difference between methods results is more than 15 % with a lack of seismic resistance. © 2019 IOP Publishing Ltd. All rights reserved

Account for the contribution of higher modes under system seismic resistance estimation by nonlinear static method

The article presents higher modes accounting method under estimation of system seismic resistance by nonlinear static method. As part of the study, in order to verify the proposed method for finding the inertial forces modified system a complex of dynamic and static calculations was performed. It is established that proposed inertial forces modified system can significantly reduce system seismic resistance lack. © 2019 IOP Publishing Ltd. All rights reserved

Account for the contribution of higher vibration modes under seismic resistance estimation of system with elastomeric supports by nonlinear static method

The article presents higher vibration modes accounting method to evaluate system seismic resistance by nonlinear static method. As part of the study, in order to verify the proposed method for finding the inertial forces modified system series of dynamic and static calculations was performed. Proposed inertial forces modified system can be applied for seismic resistance estimation of system with elastomeric supports. The results difference varies within 12%. © 2020 Published under licence by IOP Publishing Ltd

Seismic resistance evaluation of high-rising structures under ductility level earthquake by nonlinear static method

Multimodal nonlinear static method for the high-rising structures' seismic resistance evaluation has been considered in this article. The object of the study is 80-meters high wind power plant. The method for account of the higher vibrations' modes and characteristic point search modified algorithm have been offered. For results verification of the systems under ductility level earthquake the nonlinear time history analysis has been performed. According to the comparative analysis the results difference between two methods does not exceed 12%. © Published under licence by IOP Publishing Ltd

Dense ferroelectric-ferroelastic domain structures in rhombohedral PMN-28PT single crystals

We have studied a dense domain structure (DDS) appearing during polarization reversal in rhombohedral (111)-cut lead magnesium niobate-lead titanate single crystals. The complicated shape of the switching current was explained by means of non-uniform motion of the boundary between the DDS and c-domains using comparative analysis of the optical current and kinetic map. 2D-vector piezoresponse force microscopy revealed that DDS represented needle-like a-domains inside the a-domains with different vertical orientations of spontaneous polarization. © 2020 Author(s).The equipment of the Ural Center for Shared Use “Modern Nanotechnology” UrFU was used. This work has been supported in part by the Ministry of Science and Higher Education of the Russian Federation under Project No. 3.9534.2017/8.9, by the Government of the Russian Federation (Act 211, Agreement No. 02.180 A03.21.0006) and by RFBR (Grant No. 17-52-80116-BRICS_a). This work was supported by the NSFC projects (Grant No. 51761145024), Shaan Xi province Project (Nos. 2017 ktpt-21 and 2018TD-024), and the 111 Project under Grant No. B14040

Tunka Advanced Instrument for cosmic rays and Gamma Astronomy

The paper is a script of a lecture given at the ISAPP-Baikal summer school in 2018. The lecture gives an overview of the Tunka Advanced Instrument for cosmic rays and Gamma Astronomy (TAIGA) facility including historical introduction, description of existing and future setups, and outreach and open data activities.Comment: Lectures given at the ISAPP-Baikal Summer School 2018: Exploring the Universe through multiple messengers, 12-21 July 2018, Bol'shie Koty, Russi

Primary Cosmic Rays Energy Spectrum and Mean Mass Composition by the Data of the TAIGA Astrophysical Complex

The corrected dependence of the mean depth of the EAS maximum $X_{max}$ on the energy was obtained from the data of the Tunka-133 array for 7 years and the TAIGA-HiSCORE array for 2 year. The parameter $\langle\ln A\rangle$, characterizing the mean mass compositon was derived from these results. The differential energy spectrum of primary cosmic rays in the energy range of $2\cdot 10^{14}$ - $2\cdot 10^{16}$\,eV was reconstructed using the new parameter $Q_{100}$ the Cherenkov light flux at the core distance 100 m.}Comment: 6 pages, 3 figures, Submitted to SciPost Phys.Pro

СТРУКТУРА, ФАЗОВЫЙ СОСТАВ И МЕХАНИЧЕСКИЕ СВОЙСТВА КРИСТАЛЛОВ ZrO2, ЧАСТИЧНО СТАБИЛИЗИРОВАННЫХ Y2O3

The structure of PSZ crystals has been studied as a function of the content of the stabilizing impurity (Y2O3) by X–ray diffraction, transmission electron microscopy (TEM) and atomic−force microscope (AFM). The hardness and fracture toughness have been measured by microindentation. The study has shown that PSZ crystals obtained by directional solidification of the melt consist of two tetragonal phases (t and t’) with varying degrees of tetragonality. Increasing the stabilizing impurity concentration leads to an increase in the volume fraction of the “untransformable” t’ phase. Experiments have shown that an increase in the concentration of the stabilizing impurity leads to a growth in the amount of positively charged oxygen vacancies (the F++–centers) which increase the lattice parameter and stabilize the structure. The character of the twinned structure changes depending on the concentration of the stabilizing impurity. In PSZ crystals with Y2O3 concentration from 2.8 to 3.2 mol. % twins first, second and third orders as well as large twins consist of smaller twin domains are observed. At high concentrations of stabilizing impurities (3.7—4.0 mol. %) the twin structure becomes smaller and more uniform. This suggests that twinning occurs simultaneously and is localized within small volumes. The character of the twinned structure changes depending on the concentration of the stabilizing impurity. This work shows that the quantity of hardening (fracture toughness) is proportional to the content of the transformable t phase.Методами рентгеновской дифрактометрии, атомно-силовой и просвечивающей электронной микроскопии исследована структура кристаллов частично стабилизированного ZrO2 (ЧСЦ) в зависимости от содержания стабилизирующей примеси (Y2O3). Проведены измерения твердости и трещиностойкости методом микроиндентирования. Установлено, что кристаллы ЧСЦ, полученные направленной кристаллизацией расплава, характеризуются наличием двух тетрагональных фаз (t и t’), различающихся степенью тетрагональности. Причем увеличение концентрации Y2O3 в кристаллах приводит к увеличению содержания нетрансформируемой t'-фазы. Экспериментально показано, что рост концентрации стабилизирующей примеси приводит к увеличению количества кислородных положительно заряженных вакансий, (F++-центров), которые увеличивают параметр решетки и стабилизируют структуру. Обнаружено, что повышение концентрации Y2O3 влияет на вид и дисперсность двойниковых доменов. В кристаллах ЧСЦ с концентрацией Y2O3 от 2,8 до 3,2 % (мол.) выявлены двойники первого, второго, третьего порядков, в свою очередь, каждый из двойников содержит внутри двойники следующего порядка. При больших концентрациях стабилизирующей примеси (3,7—4,0 % (мол.)) двойниковая структура становится более мелкой и однородной, двойникование идет одновременно и локализуется в малых объемах. Показано, что величина упрочнения (трещиностойкость) пропорциональна содержанию трансформируемой t-фазы

Natural Killer Cell Signal Integration Balances Synapse Symmetry and Migration

Imaging immune surveillance by natural killer (NK) cells has revealed that integration of activating and inhibitory signals determines whether or not NK cells stop to kill the target cell or retain a migratory configuration