Main Mechanical Characteristics Research Articles

Investigation of modification of petroleum bitumen with fine rubber crumb

Currently, in the world, due to the constant desire for recycling, many countries are considering the possibility of using rubber waste on roads. Bitumen modification for roads in Kazakhstan is considered one of the most suitable and popular approaches. This article presents the results of research on the modification of bitumen with rubber chips obtained from rubber waste. The document describes in detail the details of using rubber chips as bitumen modifiers, with particular emphasis on how they can potentially be used to improve bitumen performance and road durability. A wet process is used to produce rubber-bitumen binders. The wet process modifies the asphalt binder directly by pre-mixing with rubber crumbs at elevated temperatures, it leads to the fact that the material turns out to be the most stable, with increased elasticity and viscosity at high temperatures. The main physical and mechanical characteristics of the modified bitumen were determined after standard tests: penetration and plasticity, softening temperatures. The morphology of the modified bitumen was studied using scanning electron microscopy. The results confirm that bitumen modified with a rubber crumb with the addition of SBS meets the requirements for a polymer-bitumen binder of Kazakhstani standards and, according to its physico-chemical characteristics, is suitable for the production of modified bitumen.

Design and Development of an Autonomous Rover Application using A Rocker-Bogie Mechanism In Agriculture

The crucial topic of upgrading the rover over its earlier designs is covered in the project work "STUDY ON ROCKER ROVER AND ITS IMPLEMENTATION IN THE FIELD OF AGRICULTURE." The ROCKER rover was intended for use on similar excursions that require it to function in challenging conditions, such as the Moon's surface. However, the use of the rocker rover can be expanded even further in fields of employment where the land has to be used for operations, such as agricultural farming. Our research focuses on how the rocker rover can be modified for use in farming, greatly increasing the automation of the agricultural sector. The rover's body is entirely composed of PVC to boost. With the introduction of cutting-edge technologies, agricultural practices are changing with the goal of enhancing sustainability, accuracy, and efficiency. The design and construction of an autonomous rover with a rocker-bogie suspension system specifically intended for agricultural applications is the main goal of this study. When doing in-situ scientific investigation of goals that are separated by several metres to tens of km, rocker bogie are crucial. The complicated mobility designs of today use numerous wheels or legs. They are vulnerable to mechanical failure brought on by Mars' hostile atmosphere. a four-wheeled rover with a high degree of mobility suspension system that is effective in navigating uneven terrain. The main mechanical characteristic of the rocker bogie design is how simple its drive train is—it only requires two motors to move. Because both motors are housed inside the body, where heat variance is minimised, dependability and efficiency are raised. Because there aren't many barriers on natural terrain that call for the rover to use all of its front wheels, four wheels are used

ВЛИЯНИЕ НА КАЧЕСТВО ПРОИЗВОДСТВА ШТУКАТУРНЫХ РАБОТ ПАРАМЕТРОВ РОБОТА-ШТУКАТУРА

The article considers the main aspects of studying the effective use of plastering machines and mixtures in construction through the use of automated and mechanized systems, units and robots. Theoretical aspect of the study of the process of plaster layer compaction with the help of a vibration platform of a robot plasterer with adjustable parameters. The main design and technological parameters of vibration compaction of the plaster layer and their influence on the efficiency of the process of compaction of vertical walls are revealed. The methods of experimental research are described, as well as experimental installations on which the laboratory experiment was carried out. The use of this technology allows to solve the problem of time costs and increase labor productivity indicators, as well as aspects of economic nature. When changing the physical and mechanical characteristics of the vibration platform its dependence of variation factors allows to form the most favorable conditions for the mechanical effect of vibrations on the efficiency of the process of plastering vertical walls. Plastering mixtures for obtaining a plaster layer are studied, the main physical and mechanical characteristics are analyzed, the requirements to be taken into account in the process of plastering are analyzed. The paper presents a comparison of physical and mechanical characteristics of the vibration platform, reveals the advantages and disadvantages of using different combinations of parameters. It is established that the use of a certain combination or change of one important parameter contributes to the increase of physical and mechanical characteristics in comparison with the traditional method of mechanical action.

Understanding the behavior of the Thin Lightly-Reinforced Concrete Wall (TLRCW) building system

ABSTRACT Thin lightly reinforced concrete wall (TLRCW) buildings are commonly used to mitigate the housing deficit in developing countries. The TLRCW system comprises slender walls with a thickness lower than 150 mm, a high aspect ratio, limited or no confinement at the edges of the walls, and web reinforcement with limited ductility. This paper describes and discusses the main geometric and mechanical characteristics of 207 TLRCW buildings constructed in intermediate- and high-seismicity regions. Variables considered in the study are the number of stories, wall-area index, axial load ratio, slenderness, aspect ratio, and the type of reinforcement at wall edges. Statistical analyses of the database and global performance indices are correlated with the expected seismic performance of TLRCW buildings. The results of the analyses aided at developing a useful toolbox for rapid assessment of design and structural configuration to prioritize intervention strategies for existing TLRCW buildings.

Study of the Viscoelastic and Rheological Properties of Rubber-Bitumen Binders Obtained from Rubber Waste.

According to scientific research from different countries, crumb rubber obtained from end-of-life tires (ELT) during processing can improve the properties of the asphalt mixture, thereby extending the service life of the road surface. This paper presents the modification of bitumen with industrial rubber waste. The modification of bitumen for roads is considered one of the most suitable and popular approaches. This research paper describes the details of using different types of crumb rubber as bitumen modifiers. The modified bitumen's main physical and mechanical characteristics were determined after conventional tests: penetration and ductility, softening point, and Fraas brittleness point. In order to obtain a rubber-asphalt concrete mixture with improved performance characteristics, the viscoelastic and rheological properties of rubber-bitumen binders and their comparison with polymer-bitumen binders were also studied. The research results show that with increasing temperature, the values of viscosity, shear stress and complex shear modulus of all studied bitumen systems decrease, the values of the phase shift angle increase, and the size of the rubber particles has a greater influence on the properties of bitumen systems.

STATISTICAL EVALUATION OF MECHANICAL CHARACTERISTICS REINFORCEMENT OF CLASS A500С IN COILS

The paper presents the results of astatistical evaluation of the mechanical characteristics of reinforcement of class A500S in coils.The statistical evaluation was performed based on the results of tensile tests on 144 samples of 8 mm diameter rebar of A5000S class made of St3ps steel. The samples were taken from 8 coils of different batches of industrial production, 6 samples fromthe beginning, middle and end of each coil. During the tests, the main mechanical characteristics of A500C reinforcement were determined - yield strength (σТ), ultimate strength (σВ), ratio of ultimate strength to yield strength (σВ/σТ), relative elongation after rupture (δ5), state diagrams were drawn and the elastic modulus of the rebar (Es) was determined. The statistical evaluation was performed for each of the studied parameters (σТ, σВ,σВ/σТ, δ5) first separately for each skein for samples taken from the beginning, middle and end, then for all samples taken from the beginning, middle and end of all skeins, respectively, and finally forthe entire sample of 144 samples.According to the test data of samples from 8 coils, the yield strength of A500C reinforcement varied in the range of 532.80...631.10 MPa, the temporary resistance - 697.30...762.70 MPa, the relative elongation at break - 18.75...30.00 %, the ratioof temporary resistance to yield strength -1.185...1.344.No stable patterns of change in the mechanical characteristics of the reinforcement along the length of the coils were found. The difference between the average values of yield strength, temporary resistance, relative elongation, and the ratio of temporary resistance to yield strength along the length of the coils did not exceed 2 %.The values of the coefficients of variation and the range of the values of the corresponding mechanical characteristics of the samples taken from the beginning, middle and end of the coils were also close to each other.The yield strength of A500C rebar with a diameter of 8 mm in coils in this sample of samples was 0.9999, with a normalised value of 0.95. The coefficient of variation was 0.0328.For the established security of the calculated reinforcement resistance at the level of 0.998, the reliability factor for A500C class rebar with a diameter of 8 mm in coils was 1.109, which is less thanthe value of 1.15 accepted in the current regulatory documents.

Use of human airway smooth muscle in vitro and ex vivo to investigate drugs for the treatment of chronic obstructive respiratory disorders.

Isolated airway smooth muscle has been extensively investigated since 1840 to understand the pharmacology of airway diseases. There has often been poor predictability from murine experiments to drugs evaluated in patients with asthma or chronic obstructive pulmonary disease (COPD). However, the use of isolated human airways represents a sensible strategy to optimise the development of innovative molecules for the treatment of respiratory diseases. This review aims to provide updated evidence on the current uses of isolated human airways in validated in vitro methods to investigate drugs in development for the treatment of chronic obstructive respiratory disorders. This review also provides historical notes on the pioneering pharmacological research on isolated human airway tissues, the key differences between human and animal airways, as well as the pivotal differences between human medium bronchi and small airways. Experiments carried out with isolated human bronchial tissues in vitro and ex vivo replicate many of the main anatomical, pathophysiological, mechanical and immunological characteristics of patients with asthma or COPD. In vitro models of asthma and COPD using isolated human airways can provide information that is directly translatable into humans with obstructive lung diseases. Regardless of the technique used to investigate drugs for the treatment of chronic obstructive respiratory disorders (i.e., isolated organ bath systems, videomicroscopy and wire myography), the most limiting factors to produce high-quality and repeatable data remain closely tied to the manual skills of the researcher conducting experiments and the availability of suitable tissue.

INVESTIGATION OF MODIFICATION OF PETROLEUM BITUMEN BY RUBBER WASTE

According to scientific research in different countries, rubber granules obtained from rubber waste during recycling can improve the properties of the asphalt mixture, thereby extending the service life of the road surface. This paper presents the modification of bitumen with industrial rubber waste. Modification of bitumen for roads is considered one of the most suitable and popular approaches. This research paper describes the details of using different types of rubber granules as bitumen modifiers. The main physical and mechanical characteristics of the modified bitumen were determined after conventional tests, penetration and ductility, softening point, Fraas brittleness point. In order to obtain a rubber-asphalt concrete mixture with improved performance characteristics, the viscoelastic and rheological properties of rubber-bitumen binders and their comparison with polymerbitumen binders were also studied. The research results show that with increasing temperature, the values of viscosity, shear stress and complex shear modulus of all studied bitumen systems decrease, and the values of the phase shift angle increase, and that the size of the rubber particles has a greater influence on the properties of bitumen systems.

Effect of mechanical properties of permafrost soil on the stress state of a pipeline during settlements

A brief analysis of methods for calculating the stress-strain state of a pipeline laid in permafrost conditions is given. The analysis of models of interaction of the pipeline with the soil during longitudinal and transverse displacements is given. The tasks of the interaction of the pipeline with the soil are set to determine the place of formation of plastic zones during thawing of the pipeline section. A problem with a symmetrical formulation and a problem in which a semi-infinite pipeline is determined are considered. The places of the highest values of the stress-strain state of a pipeline with a diameter of 1020 mm when two soil massifs moved relative to each other due to soil thawing were determined. The results are shown as a change in the dependence of longitudinal stresses on the amount of displacement. The distribution of stresses in the dangerous section of the pipeline is shown, the most dangerous sections are determined. The process of formation of a zone with plastic deformation of the pipeline wall metal is shown. The main mechanical characteristics of the soil that affect the stress-strain state of the pipeline are determined, an analysis is made of the influence of the mechanical characteristics of the soil on the maximum equivalent stress of the pipeline. Keywords: permafrost; pipeline; soil; mechanical properties; numerical methods; strain; stress.

Choice of the Miniature Inertial Optomechanical Sensor Geometric Parameters with the Help of Their Mechanical Characteristics Modelling.

In this paper, the mechanical characteristics of a miniature optomechanical accelerometer, similar to those proposed for a wide range of applications, have been investigated. With the help of numerical modelling, characteristics such as eigenfrequencies, quality factor, displacement magnitude, normalized translations, normalized rotations versus eigenfrequencies, as well as spatial distributions of the azimuthal and axial displacements and stored energy density in a wide frequency range starting from the stationary case have been obtained. Dependencies of the main mechanical characteristics versus the minimal and maximal system dimensions have been plotted. Geometries of the optomechanical accelerometers with micron size parts providing the low and the high first eigenfrequencies are presented. It is shown that via the choice of the geometrical parameters, the minimal measured acceleration level can be raised substantially.

Measurements of the mechanical properties of larch at elevated and high temperature under nitrogen conditions

The mechanical characteristics of wood members in a fire are reduced as a result of strength loss of the outermost charring layer and strength reduction of the secondary outer layer in high temperature zones. The charring layer has strong oxygen isolation effects. The main mechanical characteristics of larch wood, including modulus of elasticity (MOE), parallel-to-grain compressive (fc), tensile (ft), bending strengths (fb), and ductility coefficient, were determined under oxygen-free conditions at higher temperatures. Fourier transform-infrared (FT-IR) and scanning electron microscopies (SEM) were used to analyze chemical composition and microscopic changes of wood. The results suggested that hemicellulose softening resulted in decreases in mechanical properties of wood between 20 and 70 °C. From 70 to 190 °C, FT-IR spectroscopy provided evidence that increases in MOE and fc, with relatively minor changes in fb and ft, were associated with cellulose crystallinity and lignin cross-linking/condensation. The use of SEM further indicated degradation of wood composition.

Prospects for the use of fine-dispersed recycling products of concrete processing as mineral additives for the manufacture of building mortars

Introduction. One of the most important reserves for saving material and energy resources in the construction industry is the re-involvement of recycling concrete materials (products of disposal of substandard concrete, reinforced concrete structures and products), in particular, highly dispersed powders with the prospect of their use as a mineral additive for the production of mortars for general construction purposes, in the production field. The implementation of this approach will practically ensure the introduction of the most important principle of waste-free technological processes (in the production of prefabricated and monolithic concrete, reinforced concrete structures and products) and create conditions for solving important economic and environmental problems.Aim. The aim of the work were the determining of the main physical and mechanical characteristics, comparative analysis of the mortar on Portland cement, as well as mortars with the replacement of a part of Portland cement (by 10, 15 and 25 %) with a recycling (concrete) fine powder with a specific surface area of 4500 cm2/g.Materials and methods. For the research, the following components were used: recycling (concrete) fine powder with a specific surface area of 4500 cm2/g, construction sand with a size modulus Mk = 2.31 (according to GOST 8736-2014), portland cement with CEMII/V-W 42.5N (according to GOST 31108-2020) slag, chemical additive “CENTRIPOR TFM 411R”.The selection of mortar compositions was carried out according to SP 82-101-98. Tests of mortar mixtures and mortars were carried out according to GOST R 58767-2019. Compliance with the compressive strength of mortars with the grade was determined in accordance with GOST R 58766-2019.Results. As a result of the work carried out, it is shown that fine-dispersed recycling concrete powder with a specific surface area of 4500 cm2/g can be used as a mineral additive (filler) for the production of mortars on a par with additives currently used in the construction industry of the country.Conclusions. The possibility of using fine-dispersed recycling concrete powder with a specific surface area of 4500 cm2/g as a mineral additive (filler) for the roductionof mortars on a par with additives currently used in the construction industry of the country. It has been shown that when 10 % of cement is replaced with recycled (secondary) fine powder with a specific surface area of 4500 cm2/g, the strength of building mortars of the M100–M150 grades increases and its structure improves.

Contributions to the Dynamic Regime Behavior of a Bionic Leg Prosthesis.

The purpose of prosthetic devices is to reproduce the angular-torque profile of a healthy human during locomotion. A lightweight and energy-efficient joint is capable of decreasing the peak actuator power and/or power consumption per gait cycle, while adequately meeting profile-matching constraints. The aim of this study was to highlight the dynamic characteristics of a bionic leg with electric actuators with rotational movement. Three-dimensional (3D)-printing technology was used to create the leg, and servomotors were used for the joints. A stepper motor was used for horizontal movement. For better numerical simulation of the printed model, three mechanical tests were carried out (tension, compression, and bending), based on which the main mechanical characteristics necessary for the numerical simulation were obtained. For the experimental model made, the dynamic stresses could be determined, which highlights the fact that, under the conditions given for the experimental model, the prosthesis resists.

INFLUENCE OF ADDING POLYPROPYLENE(PP) INTO POLYETHYLENE(PE) ON MECHANICAL PROPERTIES OF GEOCELLS

In the article, it will be considered what is the influence of the addition of 10% PP into a polyethylene mixture compared to a mixture of polyethylene on the main mechanical characteristics of geocells - hardness, maximum tensile strength, strength of the internal structural junctions (welds). It will be analyzed the interrelationships between the measured mechanical parameters.

Ефективність використання червоного шламу при розробці кислотостійких гібридних лужних цементів

The use of secondary industrial products has long been an integral part of the construction industry. The most common man-made raw materials used in the production of building materials, in addition to slag, are fly ash and red mud.
 This work is devoted to the study of the effectiveness of using red mud as an additional source of an alumina silicate component of man-made origin in the production of alkali-activated cements with increased acid resistance.
 In conventional cement systems, the use of significant amounts of red mud is not possible due to the high content of alkali metal compounds and heavy elements, but this is not a problem for alkali-activated binders.
 Red mud obtained by processing bauxite ore using the Bayer process is highly alkaline, and its disposal and reusability are hampered by high sodium concentrations and high pH. That is why, according to the analysis of literature sources, research on the integrated use of red mud is mainly found in only a few areas, among which construction occupies a leading position.
 In the course of research, the parameters of dough of normal density, hardening terms and strength for the developed systems were determined. Direct determination of the acid resistance index was also carried out using two methods: accelerated and by long-term aging of samples. In this way, the main physical and mechanical characteristics of the developed compounds were determined and the results were analyzed.
 The obtained results of the study confirmed the possibility of partially replacing alumina silicate components with red mud to obtain acid-resistant alkaline cements. It was found that the introduction of up to 30% of red mud makes it possible to obtain material with an acid resistance coefficient (Ks) in the range of 0.8-0.95.

Characterization and Assessment of Performance of Innovative Lime Mortars for Conservation of Building Heritage: Paimogo’s Fort, a Case Study

Along the Portuguese coastline, several military fortifications were built with the intention to protect the territory from the constant military threat from the sea. These constructions have been subjected, during centuries, to a very aggressive environment; the renders, whose main function is the protection of walls, are particularly exposed to such actions. Nossa Senhora dos Anjos de Paimogo’s Fort, better known as the Paimogo’s Fort, is one of these fortifications, built in 1674 and classified of public interest since 1957. Within the scope of the “Coast Memory Fort” Project of EEA Grants Culture Programme 2014–2021, promoted by the Municipality of Lourinhã, repair mortars are being developed for the preservation of the Fort, considering the physical–mechanical and chemical characteristics of the pre-existing mortars and of the substrate, as well as the aggressive environmental conditions. In this work, several mortar compositions, compatible with the original mortars and designed to resist the aggressive environment, are briefly described and their main physical and mechanical characteristics are analysed and compared in successive ages. Different binder mixes were used, and a fine-tuning of the aggregate was carried out. Assessment of sequential wetting/drying cycles’ effect on the mortar’s behaviour is also presented. The laboratory results reveal that mortars with additions of 30% of quicklime present the best behaviour (with the lowest water absorption and highest strength). Moreover, the substitution of part of the siliceous sand by limestone aggregate, in general, increases the mortars’ mechanical strength; however, the drying occurs slower, which could compromise the durability of these mortars if a good balance is not achieved.

Increasing the Operating Lifetime of Wearable Working Bodies of Agricultural Machines

The efficiency of agricultural machine and tool operation is noted to significantly depend on the characteristics of the working bodies. The paper emphasizes the importance of working bodies’ reliability and operating lifetime which largely depend on wear resistance, strength, as well as design features. (Research purpose) To substantiate the choice of effective modern directions to increase the operating lifetime of wearable agricultural machine working bodies, the choice of types and characteristics of the materials used and technological methods for their hardening. (Materials and methods) The many years’ experience of the FNAC VIM in this area has been studied. A concept analysis of the relevant technical information has been conducted. (Results and discussion) The basics and conditions of abrasive wear of agricultural machinery parts are presented. The concept of "structural wear resistance" is clarified. The paper analyzes the materials (steels, hard alloys) of the working bodies of the agricultural machines used in Russia and abroad. Their main comparative physical and mechanical characteristics are pointed out. A method is proposed for selecting basic design parameters based on the strength characteristics of the materials used. Surfacing technologies for hardening the agricultural machine working bodies are compared. The paper substantiates the most effective technological options, individual technical and economic parameters, recommendations for the use of materials. (Conclusions) It is proved that the use of surfacing technologies leads to a 1.5-4.5-times increase in the operating lifetime of working bodies and significant economic efficiency.

Novel Sustainable Masonry from Ancient Construction Techniques by Reusing Waste Modern Tiles

The recycling and reuse of wastes, especially Construction Waste (CW), is a fundamental way for sustainability. The act of reusing is not a modern practice; as early as in Ancient Rome and even more during the Middle Ages, materials were already being taken from existing buildings in order to reuse them in different ways. Starting from these general considerations and taking inspiration from specific construction techniques found in some Roman and Romanesque masonries made by unbroken tiles and tile fragments, two novel sustainable masonry constructive techniques are proposed here. They are composed of modern U-shaped tiles and their fragments so as to use CW. Monotonic and cyclic compression tests were performed so as to determine their main mechanical characteristics, such as compressive strength, Young’s modulus, and failure mode, and a first attempt at establishing their possible use in the construction sector is sought. A comparison with the literature values from other constructive techniques with similar values was also performed. It results that both the wall typologies showed satisfactory mechanical properties (i.e., compressive strengths are in the range of 1.28 ÷ 2.27 MPa), provided that their use is restricted for constructions of moderate dimensions.

Compression stress-strain curve of rammed earth: Measuring and modelling

This research article is about a study on the mechanical behavior of rammed earth under compression stress. The main purpose is to establish a simple stress-strain model for rammed earth. The tested rammed earthen materials are made of various local materials with different grain-size curves and grain shapes. Some of them are stabilized using cement and lime, or reinforced using barley straw and date palm fibers.The compression tests, the results of which are reported and analyzed in this article, were conducted in a monotonic manner on the produced cylindrical specimens at their almost dry state. For each compression test, the stress-strain curve is established, then the main mechanical characteristics are determined. These characteristics are the compressive strength, the initial tangent modulus, and the peak strain corresponding to the maximum compressive stress. Also, the secant modulus, defined as the ratio of the compressive strength to the peak strain, is calculated. Resultsshow that, for all the tested materials, stabilized or not, the stress-strain relationships observed can be modeled as quadratic polynomial. On the basis of this stress-strain model, the stress limit of the linear mechanical behavior of rammed earth was established. This stress limit, stated as a percentage of the compressive strength, depends on the ratio of the secant modulus to the initial tangent modulus, which themselves depend on the component materials used to manufacture the specimens.

Analysis of a Thermodynamic Determination of the Surface Tension of a Two-Component Vapor–Liquid System

A numerical analysis is performed of a thermodynamic determination of the surface tension (ST) of a vapor–liquid binary mixture and interfacial tension (IT) between two liquid phases as the excess value of free energy ΔF of a two-phase system with and without for a phase boundary. Calculations are made in the simplest version of the lattice gas model (LGM), allowing for the interaction of nearest neighbors in a quasi-chemical approximation. Each node of a two-component mixture in the LGM system can be occupied by mixture components A + B and vacancy V. The two main ways of calculating ST, expressed in terms of different partial contributions Miq to excess free energy ΔF (where i = A, B, V are vacancies; 1 ≤ q ≤ κ, q is the number of the monolayer inside the boundary; and κ is its width), are compared, as are calculations of ST and IT as excess free energy ΔF for a lattice model with no vacancies. The ambiguity of ST and IT values depending on the type of Miq functions is obtained by calculating the temperature dependence for a flat boundary and the dependence of ST and IT on droplet size at a fixed temperature. The role of vacancies in the LGM as the main mechanical characteristic of the system under the condition of strict phase equilibrium in three equilibria (mechanical, energy, and chemical) is discussed.