Physical-mechanical Parameters Research Articles

Modelling of the carding process for spunlace nonwovens with particular regard to selected mechanical parameters in a double-drum card. Part 1: modelling of the fibre deck forming process

The production of nonwoven fabric dedicated to the hygiene sector of industry is a dynamically developing market segment. Competition among manufacturers forces high performance in the economic production of nonwoven fabric with appropriate physical–mechanical parameters. One of the most important processes which guarantees that such characteristics may be obtained in the production of nonwoven fabrics, is the carding process. The article presents the modelling of the carding process on a modern, double-drum carder. The dynamics of the formation of nonwoven slivers was analysed, taking into account the homogeneity of the density of the fleece formed. In the description of carding dynamics, the mass balance of fibres was taken into account. Numerical simulations concerning the gradual increase in fibre accumulation, over time – and in relation to the fibre collection factor and the number of rollers in the worker–stripper systems – are presented.

Підвищення експлуатаційних властивостей поліграфічного обладнання

A literature analysis and patent search of technological processes for the creation of fully and partially regular micro-relief of various types and types using surface plastic deformation are carried out. Based on the inspection, the necessity of creating a combined micro-relief on flat surfaces with the task of improving the quality parameters and operational characteristics of the guides was determined. A two-stage technological process for creating micro-relief guides on flat guides of printing equipment has been developed. At the first stage of the technological process, we create a micro-relief in the form of a circle. At the second stage of the technological process, we change the modes of surface plastic deformation and, on a flat surface of the guides, a micro-rectilinear guide that passes through micro-relief circles.Experimental studies were carried out on samples of steel and cast iron. The wear resistance of samples with micro-guides was studied on a special bench. The wear of the samples by weight was estimated by the method of weight loss using laboratory analytical weights. Linear wear was indicated by measuring the depth of the micro-relief using a profilometer. The results of experimental studies have shown the optimal in terms of wear resistance area of micro-guides made of metal.The developed stage-by-stage technology makes it possible to increase the wear resistance of guides by 1.3–1.4 times in comparison with flat polished surfaces, as well as improving the geometric and physic-mechanical parameters of the surface of parts of printing equipment.An analytical relationship between the area of micro-guides and the geometric parameters of the micro-relief is established. The influence of processing modes on the geometrical parameters of the micro-relief is investigated. The optimum area from the point of view of wear resistance has been experimentally determined for the micro-guides made of metal parts.

Analysis of Surrounding Rock Vibration and the Influence of Soft Rock Mechanical Parameters During the Tunnel Blasting with Thin Bedrock Roof

The blasting construction of Shuidun Tunnel, China (a thin bedrock roof tunnel) is the engineering background in this paper. The numerical simulation method is adopted and combined with the verification of field measurement. The longitudinal, circumferential and radial distribution of the surrounding rock near the tunnel face is analyzed. The effects of various physical mechanical parameters of overlying soft rock on surrounding rock vibration are also discussed. The results may provide reference for construction safety control of similar projects. The main conclusions are as follows: The maximum value of the significant coefficient of cavity effect appears in the range of 2–4 m behind the tunnel face. The data like vault settlement within this range should be monitored emphatically. In the circumferential direction, the closer to the tunnel wall, the more significant the circumferential characteristic of the vibration velocity vector of surrounding rock is, and the maximum vibration velocity appears at the contact point between the rock layer interface and the tunnel contour wall. In the radial direction, the peak vibration velocity of surrounding rock decreases rapidly in the range of 1 m, while the attenuation tends to be gradual in the range of 2–4 m. The peak vibration velocity of surrounding rock near the tunnel face is positively correlated with the bulk density and poisson’s ratio of overlying soft stratum, and negatively correlated with its elastic modulus and internal friction angle of overlying soft stratum.

Influence of Structure and Physical-Mechanical Characteristics of Threads on the Strength of Binding the Books

In this study was analyzed the physical-mechanical properties and characteristics of different type of threads (linen, polyamide, cotton, polyester, silky) for blocks sewing. Investigated the brochure block binding with reduced threads surface friction coefficient, physical-mechanical parameters analysis. An important step in calculating the strength of threads for book sections and book blocks sewing is the choice of the strength criterion. For this purpose, are analyzed the influence of the structure of cotton and polyamide threads antifriction. Here was made the book binding process optimization with different types of the thread. It has been determined that the strongest book binding is with the polyamide type thread.

Verification of the Use of Slag Aggregate of the Heap Koněv into Concrete

The paper deals with on comparison of selected properties of slag aggregate and natural aggregate in concrete. In mixtures was used as filler the slag aggregate from Koněv heap in Kladno and for comparison was used natural aggregate from Tovačov and Hrabůvka that is commonly used in concrete. The aim of this work was to verify whether this slag aggregate can be used in cement based mixtures. In the the experiment, the basic physical-mechanical parameters of both types of aggregates were determined, mixtures were proposed and then tested. Durability properties were also verified.

The impact of various types of steel fibres on the strength parameters and blast resistance of high – performance concrete

The paper describes composition proposals and subsequent optimization and testing of developed fibre-reinforced UHPC mixtures, which seem to be optimal as construction material for the blast and ballistic protective systems, such as mobile blast-resistant walls and covers, which are the expected outcomes of the presented research project. Methods of laboratory testing and optimization of developed UHPC mixtures, with the aim of achieving the best possible values of physical-mechanical parameters, are described in this paper. In connection with laboratory verification, field blast tests of UHPC board samples and consequently of the entire blast-resistant wall system were realized and resistance to dynamic stress was investigated.

Microscopic & macroscopic characterizations of Beijing marble as a building material for UNESCO heritage sites: New insights into physico-mechanical property estimation and weathering resistance

Beijing marble has been used as a construction material for cultural heritage sites in Beijing area, China. The Forbidden City, the Temple of Heaven, the Summer Palace, and the Thirteen Ming Tombs are classified as UNESCO World Heritage sites. In this paper, detailed experimental and analytical investigations of two representative sub-types of Beijing marble are presented. Marble samples were collected from a historical quarry in Dashiwo County of Beijing’s Fangshan District. Mineral and chemical constituents were investigated through petrographical observations, X-Ray Diffraction (XRD) analysis and X-Ray Fluorescence (XRF) analysis. Physical parameters (e.g., density, porosity, water absorption, pore size distribution, P-wave velocity (VP), seismic anisotropy (AVP), hardness, etc.) and mechanical parameters (i.e., uniaxial compressive strength (UCS) and Young’s modulus (E)) were tested in accordance with British and Chinese standards. Correlations among tested parameters were also analyzed to better understand the internal relations among different properties and to aid in evaluating unattainable parameters during in-site heritage site assessments. To get a more comprehensive understanding of the marble’s characteristics, we collected and analyzed those physico-mechanical data reported by previous researchers. Additionally, the weathering mechanisms and resistance of the marbles were discussed from different perspectives. The results of this study provide scientific data on the properties of Beijing dolomitic marble, which have practical use for weathering assessments and reconstruction of cultural heritage sites. Additionally, the results of this study provide a reliable reference for studying worldwide marbles with different geological origins.

On the Distribution of Free Waves on the Surface of a Viscoelastic Cylindrical Cavity

BackgroundIn this article, to the development of the theory and methods for calculating vibrations of dissipative mechanical systems consisting of solids, which include both deformable and non-deformable bodies is discussed. Theoretically, the problem in the mathematical aspect, there are not enough developed solution methods and algorithms for dissipative mechanical systems has not yet been posed. The problems of choosing a nucleus and its rheological parameters, their influence on the frequency and damping coefficient systems have not been studiedPurposeThe goal of the work is to formulate the statement, develop the solution methods and the algorithm for studying the problems of the dynamics of dissipative mechanical systems consisting of thin-walled plates (or shells) with attached masses and point development theory.MethodsA method and algorithm for solving problems of eigen and forced vibrations of dissipative mechanical systems consisting of rigid and deformable bodies, based on the methods of Muller, Gauss, Laplace and Runge integral transform, are developed.ResultsTo describe the dissipative properties of the system as a whole, the concept of a global damping coefficient (GDC) is introduced. In the case of a dissipatively homogeneous system of the GDC, it is determined by the imaginary part of the first modulo complex natural frequency. In the role of GDC in the case of a dissipatively inhomogeneous system, are the imaginary parts of both the first and second frequencies. Moreover, the “Change of Roles” occurs with the characteristic value of the stiffness coefficient of the deformable elements; the real parts of the first and second frequencies are closest. At the indicated characteristic value of the deformable elements, the global damping coefficient has a pronounced maximum. A change in the parameter, on which the global damping coefficient so substantially depends, can be achieved by varying physical properties or geometrical dimensions, thereby opening up the promising possibility of effectively controlling the damping properties of dissipative-inhomogeneous mechanical systems.ConclusionsThe developed solution methods, algorithms and programs allow determining the dissipative properties of a mechanical system depending on various physic-mechanical parameters, geometrical dimensions and boundary conditions. A method for estimating the dissipative properties of the system as a whole (with forced vibrations) depending on the instantaneous values of the deformable elements (shock absorbers) has been developed. The developed method allows to reduce (several times) the amplitudes of displacements and stresses.

Алгоритм керування комплексним технологічним процесом зміцнення циліндричних сталевих поверхонь деталей поліграфічного обладнання

An algorithm for controlling the complex technological process of surface hardening of cylindrical parts of the transport-coordinating node of a line for the manufacture of integral covers with a wide valve is developed. This will ensure optimum machining of parts and a rational sequence of their implementation. The application of this algorithm will guarantee high quality indicators and predicted geometric and physical-mechanical parameters of the surface of the parts.Complex hardening is performed to restore the parts by increasing the microhardness, wear resistance and corrosion resistance in the surface layers. Usually, the traditional methods are used in the hardening of details of printing equipment. This is a one-stage hardening, or complex, which consists in plastic deformation of the surface with its subsequent chemical treatment. But the use of these methods is justified only under certain conditions of operation of the parts and their purpose. However, under conditions of operation of parts that are subject only to abrasive wear and corrosion, and given the required accuracy of material transmission, the desired properties of surface properties are not obtained.In view of this, the complex strengthening of the surface of steel shafts of printing equipment is carried out in three stages. The first and second steps involve the hardening of the part by surface plastic deformation. On the surface of the workpiece form a regular micro relief of hexagonal type, then apply partially regular micro relief in the form of longitudinal depressions. In the third stage of hardening of the workpiece is carried out by ion nitriding in helicon discharge.It is possible to apply the developed algorithm both to strengthen the investigated parts of specific equipment, and for any similar steel cylindrical parts. Complex reinforcement was performed to restore the details of printing equipment. This was realized by increasing in the surface layers of indicators: as microhardness, wear resistance, corrosion resistance.

ВЕРТИКАЛЬНИЙ ІМПЕДАНС ФУНДАМЕНТУ НА ШАРІ ВОДОНАСИЧЕНОГО ҐРУНТУ

Один з методів динамічного аналізу відповідальних споруд – застосування імпедансних чи передаточних функцій частоти, які можуть бути включені до динамічних розрахункових схем будівель, що проектуються. На основі аналізу традиційних та сучасних методів визначення характеристик динамічної взаємодії фундаментів споруд з ґрунтовою основою пропонується для оцінки залежності реакції по підошві фундаменту від частоти у випадках водонасичення пористого незв’язного ґрунту в основі та горизонтально-шаруватої його неоднорідності використовувати хвильові рівняння руху ґрунтової пористопружної насиченої стисливою і в’язкою рідиною основи (модель Біо двофазного середовища). Методом інтегральних перетворень визначаються символьні вирази точного розв’язку для переміщень фаз на границі основи (під підошвою фундаменту) від розподілених вертикальних гармонічних навантажень на фази. При вертикальних коливаннях малозаглибленого фундаменту (смуги) розглядаються складові реакції з боку твердої пористої та рідинної порової фаз. Функції імпедансу для жорсткої полоси з непроникною для порової рідини підошвою на шаруватій пористопружній насиченій рідиною (ППНР) основі знаходяться з розв’язку динамічної контактної задачі методомортогональних поліномів (при поліноміальних розкладаннях реакцій фаз з урахуванням особливостей на контакті) і оригінального програмного забезпечення по заданих геометричним і фізико-механічним параметрам фундаментів та моделі основи. На числових прикладах показано, як реакція (імпеданс) ППНР основи відрізняється від реакції пружного півпростору, а взаємодія між фундаментом з недренованою підошвою і водонасиченим ґрунтом неоднобічна внаслідок змінного (до знаку) тиску порової рідини у пружній пористій матриці під підошвою. Визначаютьсярезонансні частоти для моделі одношарової основи з затисненою тильною гранню в залежності від висоти шару, ширини фундаменту і властивостей матеріалу двофазної основи.

Possibilities of Processing of Slag Aggregate from Heap Koněv

The aim of this work is to find out whether the slag aggregates from heap Koněv can be used in hydraulic mixtures based on traditional Portland cement as well as in alternative binders based on alkali activated blast furnace slag.In the experiment the basic physical-mechanical parameters of prepared mixtures were determined and the durability properties of these composites were verified. The composition of the aggregate extract and its influence on the properties of the prepared mixtures and the subsequent determination of the alkaline ions in slag aggregates were also verified.

Depth effect on sandstone strength properties

Abstract The present article focuses on the study of different physical-mechanical parameters; it presents the results of a preliminary investigation aimed at experimental characterization. To simulate the mechanical behavior of the rock, a reference material needs to be chosen. The reference material selected is Sandstone, which is commonly used in this field of study. The behavior of sandstone from the region of Hassi Messaoud, which is well known for its petroleum operations, deals mainly with different mechanical sandstone properties and their varying strengths. The relationships between different depths and both of the mechanical sandstone properties were evaluated. As a result, useful relationships were found for different depths and the following properties: uniaxial compressive and triaxial test, Young's modulus and Poisson ratio.

Simulation study of the void space gas effect on slope instability triggered by an earthquake

This study aims at exploring the void space gas effect of earthquake-triggered slope instability and providing a new method for studying the formation mechanism of earthquake-triggered landslides. We analysed the basic characteristics, kinematic characteristics, initiation mechanisms and physical mechanical parameters of the Daguangbao landslide, generalized a landslide prototype, and established a geological model and performed simulation tests. Based on the seismic wave propagation theory of rock-soil mass, rock fracture mechanics and the effective stress principle, we found that the void space gas effect is due to the occurrence of excess void space gas pressure when the dynamic response of seismic loads impacts the void space gas in weak intercalated layers of the slope. The excess void space gas pressure generated by the vibration (earthquake) damages the rock mass around the void space with a certain regularity. The model test results show that the effective shear strength of the rock mass can be reduced by 4.4% to 21.6% due to the void space gas effect.

Displacement ratio dichotomy back analysis of surrounding rock-initial support system of weathered rock tunnel

The mechanical design parameters of surrounding rock and primary support of weathered rock tunnel are difficult to obtain by experiments. In this paper, taking the ratio of vault settlement to flank wall horizontal displacement as an investigation variable, we proposed the displacement ratio dichotomy numerical back analysis method (DDNBAM) to calculate the physical–mechanical parameters of tunnel surrounding rock-initial support system. Based on the DDNBAM, we presented a new method to evaluate the rationality of primary support design parameters by the ratio of the equivalent lateral pressure coefficient to the equivalent Young’s modulus with time for weathered rock tunnel in construction. The results are shown as follows: the results calculated by the DDNBAM may reasonably reflect the dynamic variations of tunnel surrounding rock-primary support system using the center cross disphragm (CRD) method; the higher calculation precision may be obtained using the DDNBAM, comparing with the parabolic-apex back analysis method previously proposed by Xu (2012); and adopting the DDNBAM may obtain more reasonable and reliable physical–mechanical parameters of surrounding rock-initial support system.

Hybrid Numerical Investigation on Soil‐Hammer Interaction during Dynamic Compaction

To investigate the mechanism of hammer‐soil interaction under the action of dynamic compaction (DC) on a coarse‐grained soil foundation, based on the theory of projectile penetration, the continuous‐discrete coupling method is used to simulate the hammer‐soil interaction process with different hammer shapes and different particle radii. The physical phenomena and mechanical parameters presented by the hammers and soil particles are quantitatively analyzed. The results show that the penetrating ability of the hammer is proportional to its lateral extrusion shearing ability and inversely proportional to its vertical extrusion capacity. The convex‐bottomed hammer has the maximum penetration and lateral extrusion capability, the flat‐bottomed hammer has the smallest penetration ability and the lateral extrusion capacity, and the concave‐bottomed hammer has a penetration and lateral extrusion ability between those of the convex‐ and flat‐bottomed hammers. The impact strength and vertical disturbance of the flat‐bottomed hammer are the strongest, followed by the concave‐bottomed hammer and the convex‐bottomed hammer. In addition, it is found that the smaller the particle size of the coarse‐grained soil is, the greater the depth of the crater formed and the smaller the contact force and the influence range of vertical disturbance. These research results reveal the interaction mechanisms of different hammer types and coarse‐grained soil, which is expected to provide reference and guidance for the design and construction of coarse‐grained soil foundations enhanced by DC.

Mechanical properties of concrete for radioactive waste repositories

Concrete casing for radioactive repositories have to meet many strict requirements. One of the most important is a radiation protection and a radionuclide inhabitation. Bentonite, with a great sorption capacity, seems to be a suitable material for this purpose. Therefore, the main aim of this study was to assess an impact of the bentonite utilization as a component in concrete mixtures. For this reason, basic physical properties and mechanical parameters of concretes containing different amount of bentonite were determined. Bentonite applications led to the open porosity growth, while the matrix densities were not influenced. Regarding the mechanical parameters, the compressive strengths as well as the flexural strengths were significantly deteriorated by the bentonite application. Despite the presented negative effect, the obtained results seems to prove a possible applicability of a lower percentage of bentonite in concrete structures not as a cement replacement, but just as a component.

Constructive-technological diagram of the rotary–string cultivator and the definition of its main parameters

Organizing technological processes in accordance with adopted system of agriculture, producers of agricultural products tend to get maximum possible yield with minimizing costs and increasing the level of soil fertility. A fallow system is one of effective systems of soil processing for accumulation of nutrients and moisture, as well as weed control. Fallow cultivation of soil is used when using this system for weed control. First cultivation is carried out with help of fallow or continuous cultivators, which have low productivity and high energy intensity. To eliminate these shortcomings, authors proposed a structural and technological scheme of a rotor-lug cultivator, the main element of which is rotor-string working bodies on flexible shaft. Tillage rotary-string work by hauling leads to propelling-rotational effects. There were obtained analytical dependences for determining speed of string required for cutting stem of weeds under different physical-mechanical parameters of stem and soil, as well as technological indicators of a cultivator’ operation. The authors obtained expressions for determining the radius of string installation from axis of rotation, angle of section installation to the direction of motion of energy means, as well as the number of strings required for guaranteed cutting of weeds deeper than the point of growth.

Development of the finishing and strengthening technological operations using SADT-technologies

The rational design of technological processes of parts manufacturing in single and small-scale production is inefficient without wide introduction of modern tools of part manufacturing automation with modern computer-based equipment and software. It is desirable to carry out of automated synthesis of single route technological processes with minimal influence of the operator on the technological environment. The technology of computer-aided design of technological processes is used to develop effective algorithms of functioning of adapted systems for control of technological processes and their implementation when taking into account interrelations with the technological environment. Automated development of technological environments of a given level of design concerning a dedicated technical system is possible on the basis of their rational functional models, created by means of CALS-technologies. The rational use of the SADT methodology with application of the principle of decomposition and development of the SADT-diagrams allows to solve the given technical problems. Therefore, the purpose of this paper is to develop and study the vibrational-centrifugal surface strengthening at the finishing and hardening technological operation to provide the required quality parameters and operational characteristics of the parts. The object of this research is a finishing and hardening technological operation. The subject of this research is method and parameters of vibrational-centrifugal surface strengthening to provide the required quality parameters and operational characteristics of the parts. The development of SADT diagrams allows to divide the technological process to technological operations, cutter–setting positions, technological steps, main machining steps etc. In this paper the principles of control of technological operation for vibration-centrifugal strengthening of surfaces of parts are suggested. The experimental device for machining of inner surfaces of parts is described. The initial and detailed model of the operation of the vibrational-centrifugal strengthening is offered. Statistical and structural analysis of technological process made it possible to establish the influence of the parameters of the vibrational-centrifugal strengthening on the geometric and physical-mechanical parameters of the surface quality and associated operational characteristics. Further research in that field will be related on the development of practical recommendations for using of the vibrational-centrifugal surface treatment for improving of the geometric and physical and mechanical parameters of parts surfaces.

Characterization of Sludge From Iron Ore Processing and Properties of Mortar Prepared by Full Replacement of Natural Silica Sand

This paper focuses on the use of sludge, which is currently a landfilled sand-like material left over from the processing of iron ore (IOP), representing an environmental burden. The incorporation of the material into some building mixtures like mortar or concrete can bring both environmental and technical benefit through the improvement of some properties of final mixture. Through the realization of the experiment programme, the authors have contributed to the knowledge about IOP and have determined the impact of this material on the properties of mortar mixture. This material is characterized using chemical, mineralogical, and granulometric analysis and then applied as 100% replacement of silica sand in standard mortar mixture. Basic physical-mechanical parameters (water demand, flexural strength, compressive strength) were tested. For the strength characteristics, both the samples with IOP sludge and samples with standardized sand (reference sample) were subjected to testing for a long-term period (14, 28, 270, and 365 days). Moreover, the capillary moisture was measured for 28-day old samples. Mortar prepared with IOP sludge shows lower compressive strength compared to the reference mixture throughout the overall time development, although the values themselves are sufficient for practical application. The flexural strength was found to be even better. The performance of the IOP sludge can be deemed as promising for practical applications when used in cement mortar.

Assessment of category of the rock burst hazard for the Charmitan gold deposit

The article analyzes the results of studying the physical-mechanical properties of the rocks of the Charmitan gold deposit (Uzbekistan) and estimates the liability of the deposit to rock bursts. It is shown that there are rocks and ores at the deposit with high strength properties that are capable to accumulate significant potential energy and undergo brittle failure. It is concluded that the Charmitan field, by the physical-mechanical parameters of host rocks, belongs to the category characterized by the manifestation of rock pressure in a dynamic form.