Assessment of the strength reliability of high-temperature heat exchangers with long service life at the design stage

The article describes a method for assessing the strength reliability of high-temperature heat exchangers with service life of several tens of thousands of hours at the design stage, when there is not enough statistical data on the operating time of elements and material properties. The method shows, how to determine the missing coefficients of variation for calculating reliability and build the function of the probability of failure-free operation, considering the change of the properties of the structural material over time. The method of visualizing the distribution of zones, both satisfying and not satisfying reliability criteria at the nodes of any finite element model, is also described

Theory of NMR as a local probe for the electronic structure in the mixed state of the high-TcT_c cuprates

We argue that nuclear magnetic resonance experiments are a site-sensitive probe for the electronic spectrum in the mixed state of the high-$T_c$ cuprates. Within a spin-fermion model, we show that the Doppler-shifted electronic spectrum arising from the circulating supercurrent changes the low-frequency behavior of the imaginary part of the spin-susceptibility. For a hexagonal vortex lattice, we predict that these changes lead to {\it (a)} a unique dependence of the $^{63}$Cu spin lattice relaxation rate, $1/T_1$, on resonance frequency, and {\it (b)} a temperature dependence of $T_1$ which varies with frequency. We propose a nuclear quadrupole experiment to study the effects of a uniform supercurrent on the electronic structure and predict that $T_1$ varies with the direction of the supercurrent.Comment: RevTex, 5 pages, 3 figures embedded in the tex

Electron linacs in NSC KIPT: R&D and application

A review is given about electron linacs of NSC KIPT and their some applications for research of radiation effects in reactor materials, channeling, plasma-beam interactions, geology (gamma-activation analysis of ore samples), as well as sterilization of single-use medical products, modification of polymers and semiconductors, isotope production for nuclear medicine etc

S-band electron linac with beam energy of 30…100 MeV

The S-band electron linac has been designed at NSC KIPT to cover an energy range from 30 to 100 MeV. The linac consists of the injector based on evanescent oscillations and the two four-meter long piecewise homogeneous accelerating sections. Each section is supplied with RF power from the KIU-12AM klystron. Variation of mean energy of the beam over a wide range is produced by placing bunches out of the wave crest in the second accelerating section. The report presents layout of the linac as well as simulation results of self-consistent particle dynamics in the linac and its present status.Лінійний прискорювач електронів 10 см - діапазону було розроблено в ННЦ ХФТІ з метою перекрити діапазон енергій 30…100 MeВ. Прискорювач складається з інжектора, основаного на коливаннях, що не розповсюджуються, і двох шматково-однорідних чотириметрових прискорювальних секцій. Кожна секція забезпечується НВЧ-потужністю від клістрона KІУ-12AM. Зміна середньої енергії пучка в широких межах забезпечується прискоренням згустків не на гребені хвилі в другій прискорювальній секції. Представлено структурну схему прискорювача, результати моделювання динаміки частинок в прискорювачі і його поточний стан.Линейный ускоритель электронов 10 см - диапазона был разработан в ННЦ ХФТИ с целью перекрытия диапазона энергий 30…100 MэВ. Ускоритель состоит из инжектора, основанного на не распространяющихся колебаниях и двух кусочно-однородных четырехметровых ускоряющих секций. Каждая секция питается СВЧ-мощностью от клистрона KИУ-12AM. Изменение средней энергии пучка в широких пределах обеспечивается ускорением сгустков не на гребне волны во второй ускоряющей секции. Представлены структурная схема ускорителя, результаты моделирования динамики частиц в ускорителе и его текущее состояние

On the issue of reducing the temperature heating of the airframe structure of a supersonic aircraft

In this paper, the influence of heating of the structure on its strength is considered in three aspects: a decrease in the mechanical characteristics of structural materials at high temperature, heating of the structure can lead to temperature stresses in its elements and elements of aircraft systems and the occurrence of the phenomenon of creep of structural materials - continuous plastic deformation of structural elements under constant load. There are several options for reducing heat flows due to modification of the basic aerodynamic layout: increasing the sweep angles of the bearing surfaces and the radius of the wing tip and the front edges of the inflows, reducing the area of the washed surface due to the “flattening” of the initial aerodynamic contours. Each of the considered existing and promising methods of thermal protection separately will not allow to fully develop thermal protection of promising reusable supersonic aircraft. A comprehensive approach is needed. At the same time, it is necessary to consider both the replacement of structural materials of panels and cladding with titanium or steel alloys, as well as design solutions for the use of fuel lines

Room temperature testing of PLA plastics

Polylactide plastic (PLA) prototypes are studied by means of additive technology to determine their strength properties in case of tension along the grain. In this article, testing of PLA and its compound PLA HP was carried out. Mechanical properties (yield limit, Poisson's ratio, Young's modulus) are determined. Analysis of results related to comparison of PLA and PLA HP was realized. Plastic is also studied using microscope for determination of adhesion influence on strength characteristics

Possibility of ABS polymers application for centrifugal wheel model manufacture by additive printing

This research is dedicated to an investigation of sample’s strength properties from different ABS polymers, produced using additive technology, because of it benefits in details manufacture less than 35 MPa load. Centrifugal wheel models are examples of such details, which could be used, when units for gas pumping in the petrochemical and oil refining industries are tested. The research of samples, produced by additive printing from ABS Carbon, ABS Plus1 (with titanium nitride impurities), ABS Plus 2 (unpainted), was performed. Polymers, manufactured by this technology, have anisotropic properties. In this investigation the sample’s strength properties along the fiber were defined. © 2019 American Institute of Physics Inc.. All rights reserved