Reliability as a Key Driver for a Sustainable Design of Adaptive Load-Bearing Structures

The consumption of construction materials and the pollution caused by their production can be reduced by the use of reliable adaptive load-bearing structures. Adaptive load-bearing structures are able to adapt to different load cases by specifically manipulating internal stresses using actuators installed in the structure. One main aspect of quality is reliability. A verification of reliability, and thus the safety of conventional structures, was a design issue. When it comes to adaptive load-bearing structures, the material savings reduce the stiffness of the structure, whereby integrated actuators with sensors and a control take over the stiffening. This article explains why the conventional design process is not sufficient for adaptive load-bearing structures and proposes a method for demonstrating improved reliability and environmental sustainability. For this purpose, an exemplary adaptive load-bearing structure is introduced. A linear elastic model, simulating tension in the elements of the adaptive load-bearing structure, supports the analysis. By means of a representative local load-spectrum, the operating life is estimated based on Woehler curves given by the Eurocode for the critical notches. Environmental sustainability is increased by including reliability and sustainability in design. For an exemplary high-rise adaptive load-bearing structure, this increase is more than 50%.

Effect of polygon-shaped wheels on fatigue fracture of fastener clips in high-speed railway lines

This paper studies the effect of wheel polygonalization and material properties on the fatigue failure of fastener clips in high-speed railway lines and puts forward the corresponding inhibition measures. Vibration frequencies excited by 24th-order wheel out-of-roundness (OOR) were analysed by on-site tests of the axle box vertical vibration acceleration. A finite element modelling method of polygon-shaped wheels was proposed, which was verified by comparing the field measurement with the dynamic simulation. The dynamic response of the fastener clip was simulated by using a rigid–flexible coupled model of the wheelset-track system. The effect of amplitudes as well as typical wavelengths of wheel OOR on the fracture of the clip was analysed based on the Miner fatigue damage accumulation ruler. The results show that when the wheelset ran at 237 km/h on the track, the 24th-order wheel OOR had no obvious effect on the Mises equivalent stress of the clip. When the amplitude of the 24th-order wheel OOR reached 0.225 mm and above, excited vibrations of about 1172 Hz were transmitted from the wheelset-rail system to the fastener systems, thus reducing the safe operating life of the clips. This phenomenon can be inhibited by setting a reasonable amplitude threshold for wheel re-profiling. Wheel eccentric wear (first-order OOR) and 12th-order OOR had lesser effects on the fatigue failure of the clip. The decrease of Poisson’s ratio or the increase of Young’s modulus of the material could cause the maximum Mises equivalent stress at the clip to increase, which might induce cracks, thus leading to the fracture of the clip. Therefore, during the production process, the Poisson’s ratio and Young’s modulus of fastener clips should be strictly controlled to ensure that they are within the permitted range.

Assessment of Chemical Fiber Air Filter for General Ventilation

Air filters for general ventilation have mainly been used to control the concentration of indoor particulate matter. In this study, the pressure differential, test dust capacity, quality factor and operating life of class F8 pleat–plate and multi-bag type chemical fiber filters were evaluated using an air filter performance test system. The results showed that the resistance increase rate of multi-bag filter (0.49 Pa/g·(cm/s)) was lower than that of pleat–plate filter (1.94 Pa/g·(cm/s)), the quality factor of the multi-bag filter was lower than that of pleat–plate filter, and the dust capacity of the multi-bag filter was much higher than that of the pleat–plate filter. The operating life of the multi-bag filter was 8 times as that of the pleat–plate filter with the measured PM2.5 of outdoor. The energy consumption of the pleat–plate filter was 2.2 times that of the multi-bag filter. Analyzing the electron microscope photos after dust loading, the dust depth of pleat–plate filter into filter material was thinner than that of multi-bag filter. The research results could provide data support for the design optimization and selection of ventilation filters and the treatment of the particulate matter in indoor environments.

Influence of waste of lubricating oil on the intensity of its aging in a marine trunk diesel engine

Представлены результаты моделирования старения моторного масла в судовом тронковом дизеле при разном его угаре с идентификацией влияния на степень окисления, срабатывание присадок (по щелочности), накопление нерастворимых продуктов, рост кислотности и смолообразования форсировки двигателя и качества применяемых горюче-смазочных материалов. Показана рациональность исследования процесса старения смазочного масла в циркуляционной системе смазки одноцилиндрового отсека дизеля в лабораторных условиях, что позволяет выдерживать контролируемые параметры комплекса «дизель – топливо – масло» (ДТМ) и снизить затраты на моторные испытания. По результатам расчетно-эксперементального исследования получена модель старения смазочного масла по удельным, приходящимся на единицу мощности двигателя показателям, которая позволяет прогнозировать его состояние в зависимости от срока службы и своевременно отбраковывать. Показана адекватность модели старения по экспериментальным данным использования моторного масла в судовом полноразмерном тронковом дизеле повышенной форсировки. Разработанная модель по указанным направлениям старения позволяет определить состав и режимы функционирования комплекса ДТМ, при которых обеспечивается ресурсосберегающее маслоиспользование в двигателях внутреннего сгорания. This paper presents the results of an engine oil aging model in a marine trunk diesel engine under different combustion conditions with characterization of the effect on the oxidation rate, the actuation of additives (by alkalinity), the accumulation of non-soluble products, an increase in acidity and gumming of the engine boost and the quality of the utilized fuels and lubricants. The efficiency of the lubricating oil aging process study in the circulating lubrication system of a single-cylinder diesel compartment in laboratory conditions is also shown in the article, this allows to maintain the controlled parameters of the «diesel – fuel – oil» system and to reduce the cost of motor tests. Based on the results of a computational-experimental study a lubricating oil aging model was obtained in terms of specific indicators per unit of engine power, which allows to predict its condition depending on the operating life and to promptly discard it. The adequacy of the aging model is based on experimental data of the engine oil use in a ship's full-size trunk diesel engine with increased boost. The developed model of the indicated directions of aging makes it possible to determine the composition and operating modes of the «engine-fuel-oil» system, which ensures resource-saving oil use in internal combustion engines.

TRIBOLOGICAL ASPECT OF ASSESSMENT OF EFFICIENCY OF FILTRATION USING MULTI-LAYER MATERIALS

This study presents the results of testing for the efficiency and effectiveness of filtration using multi-layer filter materials, and briefly presents a new technology for manufacturing filter media using these materials. The first part of the article describes the causes of the formation of impurities in operating fluids and the tribological effects of their impact. The second part is dedicated to testing for filtration efficiency and effectiveness for different filter materials. The third part of the article briefly describes the technology for manufacturing filter media using efficient but difficult-to-form materials. The testing results showed significant differences in filtering efficiency and effectiveness between the cellulose samples and the samples of filter materials based on glass microfibre layers. All of the tested multi-layer materials allow filtration effectiveness of over 90% to be achieved over the entire range of impurity sizes included in the experiment. The results of a comparative test for pressure change during filtration also indicate that glass microfibre materials have a considerably longer operating life than cellulose materials. The time after which a sharp increase in pressure occurs (due to the filter layer being filled with impurities) is nearly four times longer for multi-layer materials than for cellulose materials. The methods for cutting, forming, and joining filter materials have been developed by the author of this article and implemented at the EXMOT company.

Sustainable Manufacturing Process in the Context of Wood Processing by Sanding

The aim of this paper is the issue of a sustainable manufacturing process in the context of woodworking by sanding, as one of the most important technological operations before its final treatment, focusing on a selected pillar of sustainable manufacturing process, waste management. The first step of the experiment was to optimize the pressures of the sanding means on the surface. The optimal pressure of 1.04 N·cm−2 was chosen. The second level was to obtain the wear curves of the abrasive means with grain size 80 (evaluated by wood removal) and the optimal pressure in dependence on the sanding direction (along and perpendicular to the wood fibres and in the direction of 60° to the wood fibres) and different types of woods (beech, oak, alder, pine). The set parameters were suitable for beech and were not suitable for alder and pine. By extending the operating life of the sanding belts via appropriate choice of input factor settings it can be influenced metrics of pillar waste management-savings of material and waste minimization.

Non-Enzymatic Amperometric Glucose Screen-Printed Sensors Based on Copper and Copper Oxide Particles

Non-enzymatic amperometric glucose sensors have gained much attention in the past decade because of the better chemical and thermal stability and biocompatibility compared to conventional sensors based on the use of biomolecules. This study focuses on a novel copper and copper oxide-based glucose sensor synthesized by an electrodeposition technique through a rigorous protocol which reports an excellent analytical performance due to its structure and its increased active area. In addition, the linear response range, detection limit and sensitivity were 0.5–5.0 mmol L−1, 0.002 mmol L−1, 904 μA mmol−1 L−1 cm−2, respectively. Results show a reliable electrode as it is chemically stable, exhibits rapid and excellent sensitivity, and it is not significantly affected by coexisting species present in the blood samples; furthermore, it reports a maximum relative standard deviation error (RSD) of 6%, and showed long operating life as the electrode was used for thousand measurements of 4.0 mmol L−1 glucose solution during three days.

Numerical optimization of a multistage sorption compressor

Sorption compressors are driven by thermal cycles and have no moving parts, excluding some passive check valves. Such compressors are suitable for powering Joule-Thomson (JT) cryocoolers and can provide reliable and vibration free active cooling system with a potential for high reliability and long operating life. The thermal cycle consists of cooling and heating a sorbent material which is installed in a sorption cell, where the heating is obtained by an inner electric heater and cooling is obtained by the surrounding via the sorption cell envelope. The investigation and optimization of the sorption cells were conducted in previous work, at steady state conditions, by a one-dimensional heat and mass transfer numerical model. The current paper presents a dynamic numerical model of sorption compressors which consist of several sorption cells. The numerical model allows one to three compression stages, with any number of sorption cells at each stage. The model enables the investigation of dimensional parameters and operational parameters, and provides the low and high pressures, pressure fluctuations, and compressor’s efficiency. The current investigation focuses on a three-stage compressor for nitrogen, with low and high pressures of 0.2 and 8 MPa, respectively, and a mass flow rate of about 11 mg/s.

Mechanical Behavior of the Extraction Mud Dam for Use in the Manufacture of CEB

The aim of this work is to study the mechanical behavior of the sediments extracted from the Koudiet Meddaouar, Timgad dam (Algeria), for a possible valorization in the field for building works in order to minimize this phenomenon which is currently a concern for the operators and the persons in charge of the mobilization of the water resources. This siltation therefore severely limits its storage capacity and consequently it’s operating life. The extraction of the sediments accumulated in the dam's reservoir is therefore imperative, on the pain of seeing it perish in the medium term. These sediments are, however, of great geotechnical and mechanical value. The results of the tests conducted in the laboratory have enabled us to identify the different sediments from a physical and geotechnical point of view In front of the difficulties noted in the control of the silting up of the dams in Algeria, a very important quantity of silt being deposited annually in the dams. In order to achieve our objective, different mixtures of silt with or without lime treatment, cement glass fibers and powdered fibers were studied for the possible manufacture of Compressed Earth Bricks (CEB). The results obtained show that some of the mixtures present very interesting results in the different tests (compression and bending), verifying the conditions of the standards in force and thus allowing their use in the field of the manufacture of building materials. Doi: 10.28991/cej-2021-03091759 Full Text: PDF

Methods and results of extending the life of the International Space Station Russian Segment

The paper discusses the current status of work to extend the life of the International Space Station Russian Segment (ISS RS). The effort to monitor and maintain the ISS RS systems and modules in good working order forms the basis of the work aimed at station longevity and the safety of its crew. It describes measures taken to keep the ISS RS operational in a situation where some of the components have been taken out of production, and specified storage life for the spares, tools and accessories has expired. It reviews changes in the requirements for the operation of constituent components, systems and assemblies that were adopted to support extension of the ISS RS mission. It describes a procedure for detecting the sources of failures and malfunctions found in flight and resolving their causes, which makes it possible to take measures aimed at preventing propagation of faults and malfunctions within the shortest time possible while keeping the systems and assemblies of the ISS RS modules operational during repairs. It describes an approach to analysis of the causes of component failures, which makes it possible to classify them for the purposes of statistical analysis, on the basis of which one could evaluate failure dynamics in the course of the mission and use it for making a conclusion about the feasibility of extending flight tests of the ISS RS till 2024 and further. It provides data on dynamics of changes in the number of component failures in the course of the ISS RS mission, which show that this number does not grow. Key words: International Space Station, ISS RS, Russian Segment, operational integrity, operating life, failures.