Formation of residual strain in cross-ply fiber reinforced plastics under compression and tension-compression conditions

© 2018 Author(s). On the basis of the results of the conducted experiments it was shown that the behavior of a cross-ply unidirectional fibrous composite under tension and compression conditions differs significantly. It is argued that this difference is due to the fact that, when the [+45° /-45°]2s specimens are under tension, the fibers of the composite are under shear stresses and tension by normal stresses in the transverse direction. Under compression conditions, the sign of the shear stresses changes, and in the transverse direction the fibers are under compression by normal stresses. When cyclic compression with a maximum stress in a cycle is equal to the tensile stress, higher residual strains are formed in the composite, and the secant modulus of elasticity is lower than under tension. This effect also occurs under tension-compression, when the hysteresis loops are shifted to the region of negative residual strain

Theoretical and experimental investigations of the formation mechanisms of residual deformations of fibrous layered structure composites

© The Authors, published by EDP Sciences, 2017. On the example of a unidirectional fibrous composite made of unidirectional carbon fibre composite and cold-hardening epoxy XT-118, tests of specimens with a stacking scheme [+45 0 /-45 0 ]2s, where s is the number of monolayers, were carried out for cyclic loading by tension and compression. When the samples are stretched, both the fibers and the epoxy of composite are under shear stresses and stretching in the transverse direction by normal stresses, and under compression, under shear stresses and compression by normal stresses across the fibers. It is shown that in each loading cycle there is a consolidation of the material associated with the rearrangement of its microstructure, an increase in the secant modulus of elasticity and a decrease in the magnitude of the deformation increment at each cycle. The mechanism of accumulation of residual deformations under multiple loading of test samples was qualitatively studied and their level formed in the composite after each loading cycle was quantitatively found

Solving a navigation problem with the total electron content model GEMTEC

This article explores the possibility of improving the accuracy of positioning in single-frequency satellite radio navigation equipment through the use of an empirical model of the total electronic content GEMTEC. The effectiveness of this model is compared with that of the Klobuchar model, which is recommended for the GPS interface control document. We conducted testing at our observation points, using data from the international network of IGS stations in the GPS system. The use of the international network allowed us to select a long period of time for the testing from 2001 to 2017. As a result, it was shown that the GEMTEC model significantly reduces the average positioning errors as compared to the Klobuchar model. We also demonstrate the possibility of introducing the GEMTEC model and its full-featured use in single-frequency home-class receivers, for example, in the Russian receiver MNP-M7

STUDY OF METHANE CONCENTRATION VARIABILITY IN THE SURFACE LAYER OF THE SEA OF JAPAN IN THE CONTEXT OF SEISMIC EVENTS (BASED ON THE RESULTS OF EXPEDITION STUDIES IN 2017–2018)

A spatial distribution of methane dissolved in sea water is a critical but poorly understood factor in the context of seismic activity. Based on the results of the RV AKADEMIK OPARIN integrated geological-geophysical expedition (September 21 – October 31, 2017), this paper deals with the regularities of methane concentration variability in the surface layer of the Sea of Japan: the average growth and the average growth period were 70 % and 10 h, respectively, after each earthquake whereas a decrease in methane concentration in the sea water was 10–30 % 2–4 h before a seismic event. A decrease in methane concentration occurs irrespectively of the depth of an earthquake. The results obtained show good agreement with the published data and gaseous-geochemical monitoring materials, thus making it possible to associate seismic-related gaseous-geochemical regime not only with gas-saturated sediments but also with the water column of the Japan Basin (Sea of Japan)

Defining Relations in Mechanics of Cross-Ply Fiber Reinforced Plastics Under Short-Term and Long-Term Monoaxial Load

© 2018, Allerton Press, Inc. For cross-ply fiber reinforced plastics under short- and long-term loading conditions we prove the defining relations. It was shown that in general case total axial strain consists from residual (irreversible) strain of lateral degradation, reversible strain of material’s microrearrangement, and reversible creep strain. We consider issue of experimental determination and problems of identification of mechanical parameters taken into consideration

ИССЛЕДОВАНИЕ ИЗМЕНЧИВОСТИ КОНЦЕНТРАЦИЙ МЕТАНА В ПОВЕРХНОСТНОМ СЛОЕ ВОД ЯПОНСКОГО МОРЯ В КОНТЕКСТЕ СЕЙСМИЧЕСКИХ СОБЫТИЙ (ПО РЕЗУЛЬТАТАМ ЭКСПЕДИЦИОННЫХ ИССЛЕДОВАНИЙ 2017–2018 гг.)

A spatial distribution of methane dissolved in sea water is a critical but poorly understood factor in the context of seismic activity. Based on the results of the RV AKADEMIK OPARIN integrated geological-geophysical expedition (September 21 – October 31, 2017), this paper deals with the regularities of methane concentration variability in the surface layer of the Sea of Japan: the average growth and the average growth period were 70 % and 10 h, respectively, after each earthquake whereas a decrease in methane concentration in the sea water was 10–30 % 2–4 h before a seismic event. A decrease in methane concentration occurs irrespectively of the depth of an earthquake. The results obtained show good agreement with the published data and gaseous-geochemical monitoring materials, thus making it possible to associate seismic-related gaseous-geochemical regime not only with gas-saturated sediments but also with the water column of the Japan Basin (Sea of Japan).Пространственное распределение метана, растворенного в морской воде, во взаимосвязи с сейсмической активностью играет исключительно важную, но недостаточно исследованную роль. В работе на примере результатов комплексной геолого-геофизической экспедиции на НИС «Академик Опарин» (21 сентября – 31 октября 2017 г.) установлена закономерность изменчивости концентрации метана в поверхностном слое морской воды: после каждого землетрясения средний показатель роста составил 70 %, средний период роста 10 ч; падение уровня концентрации метана в морской воде достигало 10–30 % за 2–4 ч до сейсмического события. Снижение концентраций метана происходит независимо от глубины землетрясения. Полученные результаты согласуются с литературными данными, а также материалами газогеохимического мониторинга и позволяют обсуждать наличие сейсмозависимого газогеохимического режима не только газонасыщенных осадков, но и толщи вод Японского моря

GASOLINE OR COMPRESSED NATURAL GAS FOR LADA VESTA CNG

Представлен анализ использования компримированного (сжатого) природного газа в сравнении с бензином и сжиженным углеводородным газом. Приведены результаты экономического расчета окупаемости использования газомоторного топлива для легкового транспорта. Рассмотрены технические особенности использования газомоторного топлива.The analysis of the use of compressed natural gas (CNG) in comparison with gasoline and liquefied petroleum gas is presented. The results of the economic calculation of the payback of the use of NGV fuel for cars are presented. The technical features of the use of gas engine fuel are considered

INTRODUCTION OF PYROLYSIS TECHNOLOGIES FOR PROCESSING SOLID WASTE

Рассмотрен вопрос о способах утилизации твердых бытовых отходов. На основании анализа состава твердых бытовых отходов (ТБО), а также компонентов продуктов сгорания выдвинуты предположения о необходимости использования пиролизных печей для утилизации ТБО. Приведены данные о среднем морфологическом, химическом составе ТБО и химическом составе их компонентов. Приведены данные о химическом составе продуктов сгорания ТБО. Рассмотрены возможные режимы сжигания ТБО в пиролизных камерах. Рассмотрены существующие разработки в данной области.The question of how to dispose of municipal solid waste are considered. Based on the analysis of the composition of municipal solid waste, as well as the components of the combustion products, suggestions were made about the need to use pyrolysis furnaces for the disposal of municipal solid waste. The data on the average morphological, chemical composition of household waste and the chemical composition of their components are presented. The data on the chemical composition of the combustion products of municipal solid waste are given. Possible modes of burning solid household waste in pyrolysis chambers are considered. Existing developments in this field are considered

Дифференциально-временная коррекция ошибок позиционирования для спутниковых радионавигационных систем

The results of research of time variations of positioning errors in consumer's equipment of satellite navigation systems are presented. The shown repetition on adjacent days, peculiarity of day variation of errors, are proposed to be used for increasing accuracy of satellite navigation systems.На основе открытого авторами эффекта повторяемости суточного хода ошибок позиционирования с характерными временами в десятки - тысячи секунд в одночастотной пользовательской аппаратуре предложен новый метод повышения точности спутниковых радионавигационных систем