The process of mechanical activation of hydrated lime in the vibratory activator of the bunker type is investigated in the work. Economic and environmental effect in the production of reinforced concrete structures is achieved through the use of highly active hydrated lime as a modifying reinforcing additive to concrete based on Portland cement. Theoretical and experimental studies of the influence of vibration displacement parameters of the mixture on the rate and degree of dispersion of hydrated lime and the efficiency of vibroactivation are determined.

The paper presents a study of wave processes occurring in the experimental measuring acoustic probe. The probe is designed for contactless measurement of linear dimensions and micro-movements of physical objects using acoustic oscillations in the sound range. In the course of the study, an equivalent circuit of the probe in the form of a T-link band electric K-filter was drawn up. According to the design geometric parameters of the acoustic probe, the electrical parameters of the K-filter components are calculated. To verify the theoretical results, a set of experimental equipment was developed, and a method of experimental research was developed. Experimental studies have confirmed the possibility of designing acoustic probe using the proposed method of calculating the geometric parameters of its elements.

The formalized algorithm of calculation of rectangular matrix of press-form is developed on durability and inflexibility with the purpose of determination of optimum geometrical sizes which would provide it optimum operating capacity. For this purpose CAD and CAE systems were used, in particular Solidwork, Matcad. A three-dimensional model of the mold matrix was designed. Research and analysis of the stress-strain state of the matrix was carried out and its optimal parameters were determined. As a result, it makes it possible to optimize the structure of the matrix in terms of stiffness and stability and ensure its optimal performance.

The construction of a non-linear mathematical model of movement and interaction of the commanding and executive components of vibration systems is an important task. It implements vibration technologies of separation, grinding, mixing, compaction, transportation, surface product processing and technology for regulating the vibration effect on systems and mechanisms for their further research to increase the efficiency of vibrating machines, devices, and mechanisms and relevant technological processes. The article presents a generalized diagram of a five-container vibration system. On its basis, a mathematical model was developed, which in the future will make it possible to research the effectiveness of vibration machines, devices, and mechanisms. The calculation scheme of the system and the methods of nonlinear mechanics were used to build the mathematical model. The obtained mathematical model makes it possible to determine the horizontal and vertical components of the amplitude of any point of the containers of the vibration system. This will make it possible to investigate the influence of different modes of operation of the system on the amplitude and nature of vibrations of the containers, in particular, established regimes, influence reversing of the drive, the influence of the processing environment of the containers of the vibration system, influence processed parts.

The involvement of computer graphics technology is need for the training of specialists in engineering specialties. The concept of the necessary software has been developed, as well as current technical issues have been addressed, in particular, the choice of engine for working with computer graphics. The influence of the main factors on the parameters of rescue equipment is considered, including fire trucks. Special software is given as an example and the work of the developed software is described. Based on the analysis of the model, there can be establish the characteristic data that determine the stability of the rescue vehicle. The developed mocaps of the mobile application allow the analysis of the operation of special equipment.

Meet a claim is quite difficult in real production, even in specialized drilling manufacturers. Therefore, the development of reliable criteria for approaches to improving the technology of tricone drill bits is an urgent problem. This is great practical importance for domestic enterprise. The task is set to create rock-destroying insert in the basis of the developed construction. This allows you to increase the reliability of the connection between the cutter insert and the body of the cone. Favourable conditions should be provided for the rational distribution of contact stresses in conjugate surfaces "carbide cutter insert - bush - body of cone". Crucial part here is required rigidity of the carbide cutter insert. Advanced requirements are placed on them regardless of the design and dimension-type of tricone drill bits. They must have higher requirements such as: high reliability, durability of responsible elements of support and rock-destroying equipment, productivity, ability is stand destructive forces and torque are brought through a bit for influence on a face. This increases the reliability of its connection with the body of the drill bit. Requirements apply to the design to provide favorable conditions for the rational distribution of contact stresses in conjugate surfaces "carbide cutter - bush - body of the bit cone". The obtained results of stress state modeling indicate that, as expected, with the same forces acting on the insert cutter from 42 kN to 57 kN, the most intense place on the cone will be the "collar" near the cutter. The intensity of stress will be up to 1050 MPa in this place for cones with serial rock-destroying equipment. At the same time, the intensity of stress will be up to 900 MPa for cones with developed destructive equipment, this is 14 % less.

Corrosion is one of the main processes that cause problems when using metal implants in the environment of the human body. Due to its properties, titanium and its alloys are currently the most widely used biocompatible materials. But the use of implants made of titaniumbased alloys is not always successful. The purpose of our research was to establish the reasons for the rejection of a Swiss firm's dental implant made of Grade 5 titanium alloy. Implanted in the patient's jawbone, it worked as a support for an artificial tooth. But after 1 year of operation, inflammatory processes began at the implantation site, which ultimately led to rejection of the implant. To establish the material science reasons for this, we conducted microstructural studies using an electron microscope Zeiss EVO 40XVP. The sample was metallograpically prepared by grinding, polishing, and etching by using Kroll's Reagent. A statistical image processing program was used to estimate the quantitative ratio of the phase components of the implant alloy Image J. Elemental analysis and mapping elements were also performed to know the compositional and distribution of each element Ti, Al and V by using energy dispersive X-Ray spectroscopy coupled in SEM. The hardness value was determined using Vickers microhardness tester. The conducted studies established that the working surface of the implant suffered corrosion damage during operation. The edges of the implant are uneven with open and closed pitting. In some places, the merging of several pittings is observed, which leads to the occurrence of ulcerative corrosion. Elemental analysis established the redistribution of chemical elements in the surface layers as a result of contact with the biological environment of the human body. Unstable compounds are created on the surface, which dissolves in the human body during use. As it follows from the conducted studies, the degraded surface of the dental implant needs additional protection.

Індекс рубрикатора НБУВ: К222.234.062.2

Шифр НБУВ: Ж44086 Пошук видання у каталогах НБУВ 

Due to their simplified spatial shape, shell cylindrical designs have acceptable manufacturability. The latter makes it possible to use a variety of fusion welding methods in their manufacture, including the option of mechanized welding in protective gas environments. Such a technological process is considered to be sufficiently developed in terms of theory and application, as evidenced by specialized equipment for it and numerous recommendations for the selection of installation and running welding parameters. Analysis of such material demonstrates that the basic technology is welding in the lower position with a seam root lining or with the use of a suitable technological arrangement for rotating large structures to provide such conditions. Much more difficult to meet the quality requirements for a welded joint are repair and welding works of non-rotating structures with a one-sided approach to the welding zone and the absence of a seam root lining. In this case, welding equipment with electric or electric-mechanical control of the process of dropwise transfer of metal into the bath is used, regardless of the spatial position of the seam. However, in cases of single production or repair welding, classical welding sources are still widely used, in which the regulatory requirements for the weld are provided by its appropriate external characteristics, the effect of self-regulation of the arc and dynamic characteristics. Here, the variant of droplet transfer with a short circuit of the droplet to the bath is typical, with the characteristic instability of energy accumulation/return of the source choke at the stages of the arc and droplet and the corresponding behavior of the arc in different spatial positions. Since the parameters of the mode are interdependent and, thus, welding itself represents a poorly organized system that has a variety of physical parameters that cause different in nature, but tightly interconnected processes in the zone of weld formation. The best tool for assessing the condition and regulation of such a system today is planning an experiment with independent controlled (setting) parameters of the welding mode and quality feedback - the optimized amount of weld penetration. On the basis of the processing of the array of recommended data regarding the selection of the value of the setting parameters of the welding process by the procedure of constructing symmetric histograms and the distribution polygon and calculating the analytical model of the description of the distribution density for each setting parameter of the process, their average values are set with a probability of 0,9. The latter were used to calculate the actual values of the following parameters for welding a given material thickness - electrode wire diameter 1,6 mm, welding current 190 A, voltage 25 +- 1 V, welding speed - 26 - 42 m/h, wire feed speed 21 - 29 m/h, electrode discharge wire 16 mm. On the basis of the specified reference base of parameter values, a planned experiment was set up and implemented to find the optimum on a matrix of a composite symmetrical three-level plan, as variable factors are set - process voltage, welding wire feed speed and welding speed; the height of penetration of the assembled parts is set by the response. The region of the optimum and the influence of the setting parameters of the mode on it, as well as the analysis of its response surfaces and cross sections of such surfaces demonstrate that the setting parameter - the source voltage should practically be constant at the level of 24 V and does not have a significant adjustment ability for the correction of the welding mode. The setting kinematic parameters of the mode are the wire feed speed and the welding speed, respectively 23 and 27 m/h, at the given arc voltage, they provide welding in one pass. In terms of the depth of the ability to adjust the quality of the seam formation, the welding speed prevails, since, all other things being equal, the wire feed speed is strictly correlated with the speed of its melting at a given diameter and electrode distance. The latter determine the actual value of the current, the value of which is limited by the source voltage, which is strictly specified and constant for the given process under study.

Індекс рубрикатора НБУВ: З844-040.6

Рубрики:

Радіоапаратура (радіоелектронна апаратура)

Шифр НБУВ: Ж44086 Пошук видання у каталогах НБУВ 

The purpose of this work is to justify the feasibility of using the technology of microplasma sputtering from wire materials to obtain porous coatings for biomedical purposes, the modulus of elasticity of which is close to the corresponding characteristic of human cortical bone tissue. Analyzed the influence of the technological parameters of the microplasma sputtering regime on the degree of porosity of the coating. As a result, it was found that a decrease in current strength and consumption of plasma-forming gas, as well as a decrease in the speed of feeding the sprayed wire into the plasma jet lead to an increase in the porosity of the coatings. Even though these parameters are interrelated, for each individual material are limited by certain limit values, in case of nonobservance of which the stable process of melting and dispersion of the sprayed wire in the plasma jet becomes impossible. Established the limit parameters of the microplasma sputtering process for titanium alloy VT1-00 and zirconium alloy KTC-110, which allows obtaining a coating with maximum porosity. Conducted studies of the adhesion strength of the obtained coatings, formed through a low-porous sublayer, with the maximum degree of porosity according to the ASTM C633-13 (2017) method which proven that the indicators of the adhesion strength of the coatings to the VT6 titanium alloy base at normal separation meet the requirements of the international quality standard ISO 13179-1:2021.

In the article a methodology for researching wave processes in weakly nonlinear homogeneous one-dimensional systems - elements of machine and building structures is proposed. It is based on D'Alembert's method of constructing solutions of wave equations and the asymptotic method of nonlinear mechanics. Resonant and non-resonant cases are considered. In the non-resonant case, the influence of viscoelastic forces and small periodic disturbances on the oscillatory process is taken into account. In the resonant case, the influence of the disturbing force and the phase difference of natural oscillations is considered. Numerical methods for linear differential equations were used to analyze the obtained differential equations.

The present study focuses on the characteristics optimization of the physical instruments with the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The hypothesis in this research work was that the characteristics of spectrometers and rheometers could affect their rankings, which in turn could be influenced by the underestimation of their cost criterion. In this paper, the characteristics optimization of the FTIR spectrometers and rheometers was carried out with TOPSIS. Moreover, its modified algorithm was also used in order to analyze the inappropriate consideration of these instruments due to category confusion. The modification of TOPSIS helped obtain an automated decision-making method for the treatment of data. The results showed that the rankings of the FTIR spectrometers and rheometers were different as expected. Moreover, the rankings of the FTIR spectrometers were different with using the unmodified and modified TOPSIS; however, that of the rheometers did not change. The change in the ranking of the FTIR spectrometers was due to the application of the fuzzy disjunction in the TOPSIS code. In this case, the first and second candidates were placed in the first and second positions, respectively, whereas the second candidate had a better rank than the first one in the analysis with the unmodified TOPSIS code. The rank improvement of the first candidate in the category of FTIR spectrometers after the modification of the TOPSIS code was also observed. The results of this work can be used in mechanical engineering and materials science as the appropriate use of instruments in these fields depends on the consideration of their characteristics for which their optimization in comparison with those of other instruments could provide interesting results. Such investigations would provide complementary data for the experimental approaches in further applications.

Індекс рубрикатора НБУВ: К391.91-1

Рубрики:

Виробництво композитних металокерамічних матеріалів і виробів

Шифр НБУВ: Ж44086 Пошук видання у каталогах НБУВ 

The formation of the microtopography of the machined surface is one of the most critical factors in ensuring the effective operating properties of the product. These are indicators such as wear resistance, fatigue strength, provision of friction parameters of moving joints, etc. The most important reason for the formation of microroughness is vibration in the technological surface of the machine-tool-tool-tool-workpiece. This article is devoted to describing a new method of modelling the dynamic processes of machining. The peculiarity of this technique is using the results of rheological modelling (DEFORM). In addition, the consideration of regenerative vibrations of the tool is the difference of the described model. Regenerative oscillations arise due to surface roughness, which will be processed as a result of the previous technological stage of mechanical treatment. The mathematical model and the research results are described in the article. Recommendations for reducing oscillations are given.

Using the apparatus of the special periodic Ateb-functions in combination with the asymptotic methods of nonlinear mechanics, the nonlinear mathematical models of motion of working environment of the oscillation system, which dependences take into account resilient and viscid making tensions from descriptions of the deformation state of environment, her physical and mechanical properties and features of co-operation of environment with the oscillation system, are worked out. The nonlinear model for describing the dynamics of the working environment of oscillating systems is more flexible, because the nonlinearity index, which depends on the type of working load, significantly affects the results of the oscillating loading process. It allows us to take into account the type of load, and, accordingly, increase the level of adequacy of the constructed analytical model of the oscillatory process that needs to be investigated. Taking into account this model, the study of various processes in oscillating systems can be carried out, in particular in different modes of vibration processing.

The article deals with the field of machinery, namely, with the protecting of devices for mechanical driving systems. Safety-overrunning clutches, operating on gearing principle, where safety and overrunning parts are mutually integrated, are perspectives for the building based on modular machines. This case is due to their compactness and low components, comparatively with combined constructions.New clutch design is investigated insufficiently. Particularly their calculation methods, namely parts contact stresses determination, developed deficiently. For balltype overrunning clutches, contact strength calculations are well-developed, but its transference on new construction safety-overrunning clutches is impossible because of the difference between parts contact interaction in those clutches. The aims of the article are: to analyze created by authors safetyoverrunning ball-type clutch parts contact interaction features; to propose on its base clutch construction improvement which could provide parts contact stresses minimization out of dependence with clutch manufacturing and assembling accuracy; taking into account Hertz contact interaction theory results, to obtain expressions for determining clutch parts loads and contact stresses. It is established that using safety-overrunning clutch grooves parallel to radius side surfaces is inexpedient. This can increase balls and internal semi-coupling grooves edge contact and significant contact stresses. To exclude the impact of clutch parts manufacturing and assembling accuracy on contact stresses in paper, proposed to incline grooves side surfaces at an angle to the semi-couplings radius, passing through the ball centre in diametric section. Comparatively, contact grooves inclination to radius with the edge allows decreasing contact stresses in 45 - 55 times. Further investigations should be focused on force parameters and operating characteristics justification for a clutch with inclined grooves proposed in this paper.

Шифр НБУВ: Ж44086 Пошук видання у каталогах НБУВ 

The analysis of works in which designs of the dust collecting devices which are often used in the industry are investigated is carried out. It is established that forecasting the work of dust collecting devices in certain conditions is most effective to perform methods of numerical modeling and simulation of the separation process, which are widely used for research of devices of this type. Using numerical simulation methods, it is defined the structure of the gas flow in the cyclone with intermediate dust removal for different modes of operation, which was obtained by suction of gas through the dust unloading holes at constant total costs. For this cyclone, the change in the radius of the tangential, radial, and axial velocity component for different operating modes is investigated. In the course of the research, it is established that in the separation space the tangential component of velocity with increasing radius changes according to the parabolic law. The maximum values are 16 - 17 m/s. The suction of part of the gas in the amount of up to 20 % through the dust unloading holes slightly reduces the tangential component of the speed (up to 5 %) in the separation zone. It is determined that in the conical part the maximum values of the tangential component of the velocity decrease to 6 - 7 m/s. The reduction occurs both due to the flow of gas flow from the descending to the ascending, and the suction of gas through the dust unloading holes. It is established that the radial component of the velocity varies from 1 m/s in the separation zone to 5,5 m/s in the conical part. It has been found that the suction of gas through dust unloading holes in the amount of more than 15 % of the total volume leads to a change in the direction of the radial velocity component in the conical part. It is determined that the axial component of the velocity of the separation zone receives maximum values of 9 - 11 m/s. In the conical part of the device, it decreases to 2 - 4 m/s. The suction of part of the air through the dust unloading holes leads to a shift of the axis of the internal vortex relative to the geometric axis of the apparatus below the lower end of the exhaust pipe. It is established that the creation of a directed flow of gas through the dust unloading holes in the additional dust collector in the amount of up to 15 % of the total gas volume contributes to a more efficient operation of the dust collector. A further increase in the amount of exhaust air leads to greater turbulence of the flow and less efficient operation of the apparatus.

Currently, there is a tendency to increase the depth of gaseous and liquid fossils extraction. Therefore, prospecting and developing new deposits is promising. There is also a need to create new freshwater sources and implement relevant geological work based on this need. It is essential to have information about the characteristics of the explored slabs and the geology of the fields in general. Implementation of engineering and geological core drilling exploration is the most acceptable and provides the necessary data. Here, the peculiarities of the technological schemes of the process implementation make it possible to obtain separate sections of structures at a depth of the drilling equipment. It is essential to use traditional equipment, recommended for decades and provides the necessary results [1 - 3]. In the drilling process, you can achieve different diameters and depths of wells execution, obtain fossil samples etc. Engineering and geological exploration drilling is now taking on increased use in various industries [3]. Therefore, the problem of providing highquality drilling tools, the stability of their operating characteristics, and the possibility of usage in different conditions is an urgent need today. Modern drilling problems determine the usage of components of the core set with the appropriate physical and mechanical characteristics. Especially it relates to elements close to the drilling tool and the place of fossil; destruction - drill pipe. It is installed immediately after the crown core drill and receives almost the same loads and effects during working [1 - 3]. Conditions for the implementation of the process of core drilling are characterized primarily by the effect on the elements of the significant axial and twisted core set forces. There is the influence of the corrosive and active environment of the fossil in the washing and lubricating liquids well, etc. High temperatures are also observed at the drilling sites [3], which negatively affect the working tool and speed up its operation. As a result, there is an intensive shock, and abrasive core pipe wear and operation indicators change their constructive size. As a result, it is necessary to replace the operated drill string periodically. Considering modern technical and economic factors, it may be decided to repair a pipe to its original size in many cases. There are tasks for providing the appropriate characteristics of the core pipe surface. It is possible to model such properties of the new surface that functionally the best meet the conditions of the drilling process of a given geological formation. The peculiarities of applying the therapeutic layer on the surface of the core pipe are investigated in work. The experience shows that using electric arc surfacing under the flux layer is expedient. This provides the necessary adhesion of the applied layer and promotes obtaining resistance to the operation surface of the core pipe. At the same time, there is high-quality protection and the possibility of additional alloying through the flux-slaggy welding bath. Using electrode powder type wires creates conditions for flexibility to achieve the established characteristics of functional layers [4 - 6]. The filling flux, located in the cross-section of the electrode wire, can be easily changed by chemical composition. At the same time, it is possible to make relatively small parties of a wire with the set characteristics. The technological scheme justification about the core pipe surfacing is performed. It provides the previous displacement of the electrode butt size from the zenith of the core pipe to prevent the welding bath from spreading. The structural pipe size , the requirements for residual deformations, and the conditions of shapping the welded layer show the practicality of welding on a helix.