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Copyright of Cybernetics & Systems Analysis / Kibernetiki i Sistemnyj Analiz is the property of V.M. Glushkov Institute of Cybernetics of NAS of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. The implementation of modular buildings leads to the necessity to develop methods of their calculation, including dynamic loads too. One of the main parameters in the calculation of loads from dynamic effects is the determination of natural frequencies of vibrations of the structure. The subject of research is the natural vibrational frequency of modular buildings. The aim of the research is to determine the effect of the compliance of intramodular joints on the vibrational frequencies of modular buildings.Materials and methods. The paper deals with the determination of the first natural frequency of vibration of a modular building with semi-rigid intramodular joints, and the influence of the compliance of the joints on the frequency. The author of the paper proposed and substantiated an analytical formula for determining the natural vibration frequencies, taking into account the stiffness parameters of modular buildings and the rigidity of intramodular joints. The proposed formula has sufficient accuracy for engineering calculations. At the same time, it allows to analyze the natural vibrational frequencies of modular buildings with different parameters without constructing calculation schemes in computer systems, which significantly speeds up the search for rational design solutions.Results. According to the obtained results, the discrepancy in the frequency values calculated by the finite element method and analytically for a one-story building with different ratios of the rotational stiffness of the joints does not exceed 1.5 %. For a multi-storey modular building, the difference in determining the natural vibration frequencies increases with the number of storeys, but does not exceed 10 % for three storeys.Conclusions. Based on the example of a modular building, it is shown that it is necessary to take into account the joint rigidity to determine the correct value of natural vibrational frequencies. Ignoring of the rotational stiffness of the joints can lead to an error in determining the dynamic effects.

Loading and unloading operations are an integral part of the technological process of construction. Cranes of various types are mostly used to perform these works. In modern industrial and civil construction, tower cranes of the stationary type are widely used, which are used in the construction of various types of structures and buildings. Today, it is impossible to imagine a panorama of a city or a fairly large rural village without the upward, light openwork silhouettes of tower cranes. They are clearly visible against the background of new residential buildings, wherever progressive changes are taking place, where construction is underway. More than 200,000 tower cranes are used on construction sites in the country today. But when using tower cranes, special attention must be paid to their operation in adverse conditions, because they are mechanisms of increased danger. One of the important factors in the unfavorable conditions during the full-scale Russian invasion of Ukraine was the shock waves that arise as a result of missile strikes. These shock waves, in turn, cause air pressure and oscillations on the Earth's surface and cause certain seismicity. To ensure trouble-free operation and increase the reliability of tower cranes, it is important to take into account dynamic loads, which are several times greater than static loads, when calculating structures and components of their working equipment. Ensuring the stability of stationary tower cranes, especially in the conditions of martial law, is one of the important theoretical and practical tasks. The most important aspect of solving this problem is ensuring stability under the conditions of air shock waves, which cause the effect of dynamic loads on the metal structures of the crane.

An increase in the rate of coal mining and a reduction of its prime cost can be ensured by comprehensive mechanization and automation of the system of mine auxiliary transport through the widespread introduction of overhead monorail tracks. The potential use of mine monorail tracks are conditioned by the following factors: low payload ratio of the train; reduction of the mine workings cross-section area due to transfer of auxiliary transport to the upper part of the workings; high operational safety; as well as the possibility of dismantling the track in the unused sections and subsequently installing it in new mine workings. The use of rubberized rollers in the drives of mine monorail locomotives enables the coefficient of adhesion of the wheel with the monorail to be increased. It also reduces dynamic loads and the noise level during operation. The purpose of this research is to assess the durability of polymeric rims of drive wheels for mine monorail locomotives, taking into account their operating conditions. Stress distribution over the contact area of the wheel rim with the monorail was determined, enabling the development of measures to increase the service life of drive wheels of mine monorail locomotives to be developed. It was established that the effect of the monorail track deformation has no significant impact on the durability of drive wheel rims of mine monorail locomotives. A mathematical model was obtained to determine the durability of drive wheel polymeric rims, taking into account the maximum dynamic forces arising during the contact of drive wheels with the monorail. The durability of wheel polymeric rims of mine monorail locomotives was assessed in accordance with the Bailey criterion with regard to the maximum values of dynamic contact loads arising during the monorail train movement. It was also established that an increase in the carriage mass from 20 to 47 kN leads to 32 % less durability of a monorail locomotive drive wheel rim (from 8700 to 5900 hours).

The quality of well anchoring is a very urgent problem in the field of well cementing. During the development of the field, the well is subjected to both static and dynamic loads, while it is worth noting that the influence of the dynamic component is more significant, since when the cement stone is destroyed, complications associated with premature watering of the well may occur, and overflows may occur. The paper considers the analysis of the causes of the well support tightness breach during operation and selects a composition that increases cement stone strength characteristics. Relevance. The quality of well cementing is an urgent problem today. Due to the high complexity of predicting the behavior of rocks with various types of cements, situations related to the leakiness of the borehole often arise. Tthey lead to complications and accidents, and this in its turn increases the cost of work and the cost of their elimination. There are many works aimed at solving the problem of tightness quality, but despite this, the problem has not been solved and remains relevant and important in this field of research. Purpose: to develop the composition of a grouting mixture with high resistance to various loads to increase the strength characteristics of cement stone, in addition, it is necessary to consider the most promising additives, in particular, elastomers; to investigate their influence on the basic properties of cement mortar and stone. Methods. To achieve this goal, a literary review of foreign and domestic researchers was conducted. Laboratory tests of grouting mortar and cement stone with the addition of various concentrations of elastomer additives were carried out. The methods of determining the Young's modulus and the Poisson's ratio of the grouting stone are considered and applied. All studies were conducted in accordance with SS 34532-19 «Grouting cements. Test methods», SS 28985-91 «Mountain rocks. Method for determining deformation characteristics under uniaxial compression», SS 21153.3-85 «Mountain rocks. Methods for determining the tensile strength at uniaxial tension». Results. During the experiment, cement mortars with additives: latex and rubber crumb of different fractions (concentrations differ), were obtained. It was found that at the concentrations under consideration, the density of the solution decreases, the spreadability value increases, except for the concentration of 4 % latex, and the water separation of the solution with the addition of latex decreases. There was an increase in flexural and tensile strength for all samples. The composition of the cement mixture with the best indicators of the content of 3 % latex and 3 % rubber crumb fractions of 1–2 mm was determined. Conclusions. The developed composition of the grouting mixture with the addition of elastomers improves the quality of the support and has high resistance to dynamic loads during well operation.

Copyright of Metallophysics & Advanced Technologies / Metallofizika i Novejsie Tehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Issues are considered that are associated with the determination of dynamic loads encountered in moving units of the planetary mill. A horizontal planetary mill was chosen for compiling a dynamic model, as it has a great potential for organizing a closed grinding cycle with continuous loading and unloading of material. Calculation schemes were drawn up in moving units at the moments of the beginning of its operation and the steady movement of the grinding drums. Using the d’Alembert principle, taking into account the geometric parameters of the grinding unit, the reduced moments of inertia and moments of forces, as well as the acceleration time from a state of rest until the carrier reached a steady angular velocity, were determined. From the condition of equality of the power of the reduced moment of forces acting on the link of reduction, and the power of all forces and moments applied to the links of the planetary mill, the initial torque applied to the carrier was determined, which is necessary in the future to determine the power expended both at the moment of starting the mill, and at the time of its stable operation. It is shown that the initial torque depends on the value of the initial angular acceleration, which, in turn, can be different depending on the accepted law for changing the angular acceleration and the acceleration time to the required angular velocity of steady motion. It is also indicated that during the start-up period, the power supplied to the mill is spent on accelerating the rotation of the leading link and on overcoming various resistances such as friction forces in the units of the carrier and grinding drums.

Introduction. The launch vehicle (LV) in flight and the dynamic components of loads from the impact of a trapezoidal wind gust are considered. It is proposed to determine the dynamic components of the force factors using analytical solutions for the structure points accelerations. The work objective is to create a technique for selecting the duration of the standard gust, under the influence of which maximum loads are provided in the sections of the LV structure.Materials and Methods. The launch vehicle is presented as an uneven beam. The description of its vibrations is reduced to a system of independent ordinary differential equations that determine the motion of an equivalent system of oscillators. The equation of oscillator vibrations under the action of a trapezoidal pulse load is solved by the overlay method, and it is reduced to the calculation of the Duhamel integral. It is proposed to get the parameters of an equivalent system of oscillators based on the results of the calculation of dynamic characteristics for a finite element LV model in the Nastran program.Results. Analytical relations for the LV structure point accelerations under the action of a trapezoidal wind gust are given. For the beam model, test calculations of accelerations were carried out according to the technique proposed in this paper. These data are compared to the results of finite element modeling. With the help of analytical solutions, dependences are constructed that determine the nature of the change in the magnitude of the bending moment for different sections of the launch vehicle when the duration of the wind gust varies.Discussion and Conclusions. The presented technique provides building an equivalent dynamic model of systems with a large number of degrees of freedom on the example of a LV and obtaining analytical solutions for accelerations of points of a mechanical system under trapezoidal external action. These solutions are applicable for the study of dynamic loads. The analysis results enable to select the duration of the wind gust, at which maximum loads are reached in the sections of the LV structure. Calculations based on the analytical solutions are very economical in terms of time spent. They can be used in design calculations for preliminary assessment of loading.

High quality of purchased resources plays a critical role under the conditions of severe international competition. Raw materials, materials and components are purchase for product production and their quality is an essential part in the production of steel at OJSC “BSW – Management Company of the Holding “BMC” holding». The problem of excessively high level of dynamic loads is especially acute for roughing stands. The main reasons for dynamic overloads are intense transient processes occurring in the rolling cycle, the presence of elastic constraints and gaps in the system, imperfection of electric drive system and errors made during development. Therefore, there is a need for selection of material and manufacturing technology for mill rolls capable to withstand such loads for a sufficiently long period. Investigations of destruction causes of experimental mill roll of stand roughing group of mill 150 of section rolling shop at OJSC “BSW – Management Company of the Holding “BMC” holding were carried out. Main classification features are established based on the analysis of the fracture. The results of metallographic studies of microstructure and chemical composition of central and subsurface zone roll fragments are presented. The reason of destruction of experimental mill roll was discovered – nonconformance of roll material grade with the requirements of technological instructions and normative documentation for rough group of stands No. 1–3

When performing technological operations in the peat industry, various units with milling-type working bodies are used. They differ in design, layout, number and type of cutting elements, operating modes, and may have one or more working bodies. During operation, random forces and moments act on the cutters, which have a dramatically variable nature, which is associated with the periodic interaction of the knives with the peat deposit, its structural heterogeneity, variations in the milling depth, physical and mechanical properties of peat, the rotational speed of the cutter and the movement speed of the machine. In this case, significant dynamic loads arise in the structural elements, which leads to a decrease in their reliability, deterioration of the energy characteristics of the engine operation and technical and economic indicators of use. In the dynamic analysis of drive elements, when using machines with several working bodies, it is necessary to know both spectral and mutual spectral load densities. For their calculation, expressions were obtained that take into account the physical and mechanical properties of peat, the operating modes of the unit and their probabilistic characteristics, as well as the design features of the working body. The expressions are obtained for the case when there are several working bodies with the same diameters and the number of knives in the cutting plane. In this case, the number of planes, width, type of cutting element and type of cutting (locked, semi-locked, etc.) may differ. As an example of using the developed approaches, the calculation of spectral and mutual spectral densities of moments on cutters and loads in the drive elements of the machine for surface-layer milling MTF-14 is presented.

Introduction. Elevators in residential and public buildings are the means of vertical transport. An elevator is one of the complex electromechanical devices of increased danger. Therefore, all stages of its life cycle are strictly limited by regulatory documents. The desired levels of safety and comfort are provided through the reasonable choice of the basic parameters and a constant maintenance of the system in good condition. The key factors that affect the implementation of regulatory requirements during the operation of the elevator installation are the quality of manufacturing of critical components, the level of real workload, taking into account the actual value of the spent resource, and the implemented maintenance program. Currently, when determining the maintenance schedule for elevators, such characteristics as the density of occupancy, the level of power loads, the actual operating time of the elevator and the counts of starts of the main drive are not taken into account. This study objective is the scientific rationale of the concept and methodology for developing the program of maintenance of specific elevator installations on the basis of studies of the level and mode of loading of load-bearing units. Materials and Methods. The use of simulation modeling techniques to assess the load level of power units of an elevator installation and its kinematic indicators under the action of numerous random impacts is validated in the paper. The development of an indicator that characterizes the complex mode of elevator operation, taking into account the joint influence of the level of resource development, net operating time, number of starts, and the power load of the nodes, required the application of an expert method. The final part of the research program is the formation of specific recommendations on the maintenance schedule of elevators. It is based on the ranking of particular indicators. Results. The performance feature of the elevator installation is that the service time of a customer is a function of many random variables. Mathematical models of the formation of force impacts are based on the representation of an electromechanical elevator as a dynamic one-degree-of-freedom system. Expressions for calculating the static tension of traction ropes and torques on the motor shaft are obtained. The problem of dynamics is solved. The loads whose values are the basis for performing simulation modeling of the operating modes of the elevator installation are determined. Discussion and Conclusions. Feasibility of the regulations for the maintenance of passenger elevators is an urgent task, the solution to which determines the level of safety and comfort of passengers. Currently, the standards for the design and operation of elevator installations do not link the frequency of maintenance programs with the level of load and the amount of resource development. The paper provides a general statement of the problem and a methodology for the formation of a complex factor of the equivalent load. Mathematical models are given for calculating the power and temporary loads of the elevator, taking into account the nature of numerous random impacts.

In the process of operation of present-day mechanical equipment, dynamic loads arise, leading to the failure of parts, assemblies and mechanisms and, thus, reducing the equipment life time and operational reliability. A method has been developed for calculating the design and technological values of a pin flexible coupling with a flexible disk-type element, using the method of central compositional rotatable uniform planning of the second order and the finite-element method for calculating stresses using a computer-aided design system. The analytical dependence of the torque on the PCD (pin (centers of holes for pin) circle diameter) and the width of the flexible element with certain physical and mechanical properties was substantiated, on the basis of which the formula for the total width of the flexible disk-type element was obtained, taking into account the value of the required torque and the given PCD. In order to check the obtained dependence of the nominal torque, an additional study of couplings with the given PCD was carried out at different total width of the flexible element. The implemented research allowed determining the influence of the design characteristic values on the transmitted torque of a pin flexible coupling with a flexible disk-type element. A standard-size range of couplings with certain design and technological values has been proposed.

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The present paper presents a comparison of the performance of different flow conditioners. The numerical investigation is carried out using ANSYS FlUENT. Flow conditioners efficiency is evaluated on the basis of the ability of these devices to produce a uniform velocity profiles with low pressure loss under high-level disturbance conditions, such as those produced by gate and ball valves. A new flow conditioner device, which consists of two perforated conic plates has been designed, and demonstrated a high performance within a short distance downstream of the flow conditioner.

Known methods of testing supports create longitudinal and transverse static load applied to the support. In real conditions the majority of the damage of the supports is connected with the influence on them of dynamic loads, which can exceed the static. The proposed method allows to conduct experimental studies of cascade processes of destruction of anchor site due to a wire breakage, when the potential energy of the tension wires is converted into a dynamic influence on the design of supports.

Transient modes of bridge cranes movement determine their energy, dynamic and electrical performance, as well as productivity and durability of work. An optimal control problem of its movement has been solved while making an analysis of indicators for efficient performance of a bridge crane. Terminal and integral criteria have been selected as optimization criteria. They represent undesirable dynamic properties of the crane. Legendre method has been used to determine the possibility for achieving minimum of the optimization criterion. An analysis of the Euler-Poisson equation, which is a necessary condition for the minimum of the integral criterion, has shown that it is impossible to find a solution for the optimization problem in an analytical form. A method of differential evolution has been used in order to find an approximate solution to the optimization problem. The approximate (suboptimal) solution has been found in the complex domain, which is a limited domain conjunction of dynamic parameters and phase coordinates of the system. Limitation in the domain of the system phase coordinates (a polynomial basis function has been used in the paper) provides the possibility to attain absolute minimums of terminal problem criteria. A simulation of the bridge crane motion has been carried out in order to establish an efficiency for implementation of the suboptimal control. During this process dynamic mechanical characteristics of its electric drive have been taken into account. While carrying out the simulation, a frequency and an amplitude of the electric drive voltage in the crane movement mechanism have been changed (frequency scalar method for speed changing of an asynchronous electric drive has been used). A comparative analysis of the dynamic, kinematic, electrical and energy performance indicators of the bridge crane under suboptimal and S-curved (standard) laws of frequency and voltage variations in the crane electric drive has made it possible to establish an improvement in the efficiency of its operation under suboptimal control.

Problem. The power and speed increase of modern internal combustion engines (ICE) leads to increasing of dynamic loads in power transmissions of machine units. Analysis and suppression of dangerous oscillations require taking into account in models development technological and constructive nonlinearities, which are the main reason for a varie-ty and complexity of dynamic processes: resonances shifts, deformation of resonance curves, multivalence of oscillations, and the appearances of subharmonic regimes. The known approaches to dynamic loads analysis in power transmissions of cars with ICE do not allow explaining the nature of certain phenome-na. The means for their study are not sufficiently de-veloped. Goal. To develop the nonlinear dynamic drive model for determining causes of dangerous dynamic loads; to find parameters of the device, which lead to dynamic loads reduction. The follow-ing problems solution: modeling of gaps in gears connections; schematization of the periodic disturb-ance of a non-harmonic character; chosing the form of the mathematical description for steady dynamic processes, taking into account the features of the nonlinear drive model; chosing the effective algorithm for solving the corresponding motion equations; carrying out calculation and experimental studies to reduce the drive dynamic loads. Methodology. For study of the established dynamic processes in nonlinear models of machine units, it is proposed to use the integrated equations of the movement which are written down by means of pulse-frequency characteristics (PFC) of the linearized models: the number of the nonlinear equations is equal to number of nonlinearities. Labor input of the solution of the task practically doesn’t depend on number of freedom degrees of system that is essential to numerical algorithms of the solution of the nonlinear tasks having iterative character at the solution of problems of synthesis and optimization. The algorithm of the solution of the nonlinear integrated equations is based on an iterative method of Newton-Kantorovich of the solution of the operator equations. During the numerical implementation of the algorithm for resolving linear integrated equations on every step of iteration process, the method of quadrature formulas in pair with the idea of interpolation of a desired solution is used. Results. A nonlinear dynamical model of the camshaft drive of the fuel pump of transport diesel has been created in the form of integral equations written by using of PFC. By calculation and experimental studies it has been established that: 1) an increase in the torsion shaft diameter leads to an increase in the maximum elastic moments; 2) increasing the inertia moment of the camshaft shift the resonant oscillations into the operating range; subharmonic oscillations are possible under action of a defined load; 3) the average moment in the drive not significantly affects the maximum elastic moments; 4) the one-way outputs realization to the drive retainer does not lead to the necessary dynamic loads reduction in the drive; 5) the maximal reduction of the maximum elastic moments can be done by using a spring with 15 mm diameter, which in combination with durable gears give the necessary drive reliability. Originality. The motion integral equations for the study of steady-state dynamic processes in non-linear models of machine units, written using PFC, have a number of principal advantages over the use of traditional models in differential form: the number of equations is equal to the nonlinear elements number, therefore, the solution time of problems is practically independent from the number of freedom degrees of models. Practical value. The studies carried out have allowed establishing the mechanism of dangerous dynamic loads appearance and giving recommendations on the drive parameters change, which provides its working capacity. The proposed approach is perspective for the dynamic processes study in models with nonlinear spring linkages, the number of which is less than the number of freedom degrees.

The issues associated with determination of dynamic loads encountered in moving the nodes of the planetary mill with a belt drive are considered. The analysis of the influence of constructive and technological parameters on their size is carried out. For the study, a horizontal planetary mill was chosen, since it has great potential for organizing a closed grinding cycle with continuous loading and unloading of the material. A computational scheme was compiled, the analysis of which showed that the problem can be solved in the same plane. Since the geometric parameters of individual units of the aggregate exert a great influence on the nature of the feeding motion in the grinding drums of a planetary mill, geometric criteria reflecting the relationship between these parameters were derived. During the power calculation of the planetary mill drive, inertial forces were determined that exert a significant influence on the motion. Taking into account previously determined forces, the equations of kinetostatics were compiled. From these equations, expressions were obtained for determining the final sought-for value-reaction on the drum axis. Approbation of the methodology for calculating this reaction was carried out on a planetary mill with the dimensions of a real industrial facility. In the course of the study, parameters such as the angular velocity of the carrier, the ratio of the geometric parameters and the degree of loading of the drums varied. Changes in the required parameters were analyzed during one complete rotation of the carrier. As a result of the study, a number of dependencies were obtained. Having made an assessment of the results obtained, it can be noted that the change in the reference reaction occurs according to the cosine law in a small range. It is also established that an increase in the angular velocity and the loading factor leads to a significant increase in dynamic loads. In addition, the influence of the ratio of the dimensions of individual units of the aggregate on the magnitude of dynamic loads was investigated. The overall result of the work is the development of a method for calculating dynamic loads on the support nodes of a planetary mill, taking into account the effect of the maximum number of parameters.

The article reflects results of the experimental studies on the modifying agent’s dispersion to affect the nature of its distribution in the total volume of cement stone. An attempt was made to evaluate the strength and filtration properties of the cement stone with respect to the heterogeneity of its structure. The effect of a character of the modifying additive distribution on the permeability and strength of the cement stone was investigated, as a result it was clarified that the zone of influence of the applied dynamic load does not depend on the heterogeneity of the plugging material, and the values ​​of deformation in the cement stone depend on the dispersion, the nature of the distribution of the additive in the volume of the cement stone, the period of the modifying agent activation. The dynamic loads, which most strongly provoke the destruction of cement stone under the influence of high stresses, are considered. Using the finite element method (FEM), the ANSYS application program evaluated stresses in a cemented column, describes the process of deformation of cement stone, taking into account the heterogeneity of its structure. Based on the variability of the additive location, channel models for the most preferred localization of the modifying additive have been determined as open through cracks. The application of the mathematical model, which was elaborated, demonstrates a possibility of the maximum reduction of the water conductivity if the optimal distribution of the modifying additive in the matrix of the cement stone provided.

The urgency of the discussed issue is caused by the fact that working liquids of a hydraulic drive often contain undissolved air. If the hydraulic liquid filling the device is not exposed to a vacuum, it will be a mixture of liquid and gas. The same mixture can be formed in a hydraulic drive during the dynamic processes due to the different rates of gas dissolution and emission at pressure drop on separate areas of working environment flow. Therefore, the paper considers the influence of gas content in working liquid on dynamics of a hydraulic drive. The main aim of the study: evaluation of influence of undissolved gas percentage in working liquid on dynamics of a hydraulic drive. The methods used in the study: methods of theoretical mechanics and fluid mechanics are used setting up equations describing processes in hydraulic drive; numerical methods for solving ordinary differential equations systems, the Runge-Kutta method of the 4th order using the software package Mathcad. The results: The authors have developed the mathematical model of a logger hydraulic drive that allows investigating transient processes and have carried out the systematic calculations of the dynamics of a hydraulic drive. The conclusion: The results of calculations show that even a small amount (up to 1 %) of undissolved gas in working liquid influences the change of the basic parameters in transient processes. Undissolved gas in working liquid influences most of all in the initial period of a boom and a rotary foundation movement. The mathematical model of a logger boom and rotary foundation movement allows investigating the influence of undissolved gas in working liquid on dynamics of the hinged equipment at a design stage, and selecting as well the optimum values of drive parameters. The results of calculations of the dependence of change in an angle and angular velocity of a boom and a rotary foundation, as well as the pressure in piston and rod cavities of hydraulic cylinders are shown in the form of graphs.

Research of railway embankments in terms of physical and chemical mechanics were conducted discretely, without the creation of a coherent model of stability of layered systems, taking into account all the determining factors. The article shows that attention should be focused on the process of blurring the boundaries "crushed stone granules - layer of sand", "layer of sand - loam or clay" when running freight trains as well as the limiting stability of layered granular system. The presence of natural inhomogeneities of structure and change in the density of the underlying soils, especially in wet periods, violations of construction technology of sugrade embankment, dynamic loads on the rails due to vibrations of "bogie - train" system leads to the formation of wave-like ground subsidence. Vibration fields generated in the water and viscoplastic fluids, increase the rate of rise of water in capillaries and porous media in dozens of times because of reduced hysteresis in the contact angle of wet and wall effects. Therefore, the vibration of the field arising from the train handling, contribute to flooding and penetration of clay soils in the pore space of sand due to a significant reduction of the structural viscosity and yield value of a non-Newtonian media. In studies of clay media and other systems all the effects should be taken into account: deformation thixotropy, "gelation" in strong electromagnetic fields, wall effects, which significantly increase the flow rate of hydrated clay in suffosion capillaries of sand and crushed stone cushion layer.

Dynamic loads regularities in elastic elements of the load-lifting machines were analyzed, in conditions of actual use they should be minimized. An updated analysis of dynamic loads in crane ropes was conducted and conditions of loads minimization were determined. Modes of load movement on elastic rope of lifting crane were substantiated. In these modes dynamic factor Kd minimizes and drive mechanism performs optimum movements. At the same time methods of classical variational calculus and apparatus of differential equations (ordinary) were used, and the calculations were carried out for two classic ways of load lifting ("hanging" and "with pickup"). The updated dynamic analysis was conducted and loads that arise in elastic elements (ropes) of lifting equipment were minimized within the two-mass model. At the same time methods of load lifting "hanging" and "with pickup" were considered for various possible modes of drive mechanism motion in the starting area. Models for load lifting "hanging" and "with pickup" which minimizes the dynamic loads in the rope of the crane in its launching period were justified. The results obtained can later be used to update and improve existing engineering methods for movement mode`s calculation of lifting cranes and their components (when lifting is "hanging" or "with pickup"), these modes minimize the rope load at optimal modes of drive motion as at the design (construction) stage of such systems, as well during their real operation.

A brief analysis of the physical and mechanical properties of materials, used in the construction of the rail bed, has shown that in scientific and technical literature there is scattered unsystematic information obtained under different physical conditions for bulk materials (gravel and sand). Unstructured data on the physical and mechanical properties of granular materials does not allow formulating a relatively complete dynamic theory for a wide range of static and dynamic loads, vibration acceleration and humidity conditions in relation to rail transport. In this article the authors formulate the problem of stability of the system “clayey soils in the main area - protective layer of sand cushions - ballast crushed stone prism” under the impact of harmonic oscillations on the basis of physico-chemical mechanics. Loam or clay belongs to isotropic visco-plastic media, sand and gravel - to disperse granular media. Filling the pore space of the gravel with weeds leads to the retention of precipitation and melt liquid. During deflation processes clogging of the gravel layer is increased. Despite the enormous practical value, properties of granular materials, until recently, practically not been studied. Under appropriate conditions this material may behave as a solid and as liquid and as gas. Each phase has unique properties that distinguish granular materials from all other substances. If the vibration field is applied to layer of gravel or sand, the energy of this motion is passed even through individual granules. As a result, with sufficiently high amplitude of jitter a phase transition occurs: the entire mass of granular material gets in motion, begins to flow due to reduction in friction between the particles and behaves as a kind of “granular liquid”. Fluid state of gravel stone occurs at much large values of the amplitude of vibration because of its angular shape. The result is a hydrodynamic instability, then convection starts and the vortices spontaneously appear.

The subject of research is an influence pattern of quasioptimal quick acting movement control of lifting cranes with a load flexible suspension on dynamic movement characteristics. The purpose of the work lies in the synthesis of quasioptimal crane movement control when its accelerating with the elimination of load fluctuations, as well as in the study of the crane movement dynamics at the quasioptimal control. The paper proposed to switch from an optimal control of crane movements to control, which is described by a continuous function. In order to achieve specified final conditions of movement by the system “crane-load” an algebraic system of transcendental equations was composed, which was leaded to the target of minimizing the complex function of three arguments. By using the particle swarm method points in time were found at which there was a change in the control character (the driving force of the crane actuator). Simulation of crane movements at quasioptimal control made it possible to find its basic dynamic characteristics during acceleration. Comparative analysis of the data showed a significant reduction of dynamic loads in the crane elements. The transitional regime duration of the crane movement in comparison with the optimal control increases slightly. Thus, by increasing the duration of the crane`s non-essential movement cycle (for tens of seconds) an increase in the durability of the crane steel structures, mechanical gears, motor, power inverter, and other elements is achieved. The obtained results should be used for the development and modernization of movement control systems for lifting equipment, which require a significant productivity, energy efficiency and durability (for example, cranes that are extensively exploited in ports, metallurgical and machine-building enterprises, construction sites, warehouses).

This research is devoted to analyzing the dynamic loads generated in the glove machine at reciprocating motion of knitting and intermediate carriages. Proposed is a method for determining the maximum dynamic loads in the glove machine carriages’ drive. It is noted that the dynamic loads reduction can be achieved by equipping the drive with energy accumulation and compensation units, in which quality it is expedient to use the cylindrical compression springs. The obtained dependence allows to determine the necessary stiffness of compression springs (energy accumulating and compensating units), at which the dynamic loads due to the carriages masses’ inertia can be almost completely eliminated.

This research is devoted to analyzing the dynamic loads generated in the glove machine at reciprocating motion of knitting and intermediate carriages. Proposed is a method for determining the maximum dynamic loads in the glove machine carriages' drive. It is noted that the dynamic loads reduction can be achieved by equipping the drive with energy accumulation and compensation units, in which quality it is expedient to use the cylindrical compression springs. The obtained dependence allows to determine the necessary stiffness of compression springs (energy accumulating and compensating units), at which the dynamic loads due to the carriages masses' inertia can be almost completely eliminated. [ABSTRACT FROM AUTHOR]

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Dynamic power transients in the rope wire of single-drum and double-drum hoists taking into account the dissipation of ropes and damping devices, which significantly absorb longitudinal vibrations, reduce the amplitude and time of vibration damping are considered in the paper. Oscillatory processes in hoist ropes are described by differential equations in moments of elastic forces with constant factors and graphically shown on the oscillograms. Dynamic parameters of hoist ropes (maximum amplitude of dynamic moment, stationary dynamic loads, rope dynamic factor) when varying the dissipation factor of damping devices are determined. As a result of researches, the dependencies of dynamic factors of hoist ropes on varying the values of dissipation factor of damping devices are constructed, which show that, with an increase in the dissipation factor, dynamic factor of long ropes reaches almost 1 and of short ropes decreases slower because of their high rigidity. Using damping devices will allow to reduce the dynamic loads in the hoist ropes and improve performance characteristics of hoists in general. [ABSTRACT FROM AUTHOR]

Background. Rolling mills are important components of steel industry. Their secure work depends mostly on the level of dynamic load in mechanical equipment. There are several ways to increase the reliability of rolling mill equipment. One of them is to optimize electrical drives operation to limit the dynamic load in mechanical and electrical components. Materials and/or methods. Modern computerized control systems provide good opportunities for the optimization. Such rolling mill main drives control system is realized at metallurgical works "Zaporojstal" (Ukraine). The slabbing mill consists of two two-high mill stands with individual drives for each roll. Due to the reversing operation the optimization algorithms are different for the direct and reverse driving directions. The control system calculates and realizes the optimal ratio between main drives speeds of vertical and horizontal stands in the separate and common stages of the rolling process. It helps to limit the dynamic load during the metal acquisition. During the common stage of the rolling process the control system adjusts the speed ratio among the stands in the way to avoid the tension and dam in the billet. The speed diagram for the both main drives is realized with the hitch limitation. It helps to prevent the impacts in power transmission. The system is realized on PCcompatible industrial controllers and provides also the visualization and storage of the main drives operational parameters. Results. The measurement of torques in spindles and shafts indicates that the ratio between the maximum dynamic and steady-state loads does not exceed 2, which is a very good indicator for the large reversing rolling mills. Conclusion. The control system was designed and implemented by "RPA "Donix" Ltd. and ensures the accident-free operation of rolling mills equipment. [ABSTRACT FROM AUTHOR]

Purpose. To study the destruction character of polymineral rock of different genesis for creation of resourceand energy-saving methods of its production. Methodology. In laboratory and ground environment the structural change in the polymineral rocks of different genesis affected by dynamic loading of different intensity (high-speed centrifugal percussion installation, explosive destruction of models) has been studied by means of the x-rayed setting of DRON-3, polarization microscope of MP-2, provided with integrator of ISA. Findings. The results of granulometric and x-rays analyses of fine-size factions of the rocks of magmatic, metamorphic and sedimentary genesis, destroyed by the dynamic loading are presented. Originality. During the study of fine-size factions of sedimentary, metamorphic and metasomatic granites by means of light-optical and x-rays methods we have find out the analogy in shock and explosive destruction character of rocks with different genesis. Finely-dispersed factions of the destroyed rocks include minute particles of grains of minerals with maximal density of defects of structure. Quartz dominates in finely-dispersed factions of sandstones and ferrous quartzite. For metasomatic granites affected by the explosive loading in composition of 0-100 mkm faction the particles of albite and calcite prevail above the particles of quartz. Lines characteristic for U-containing minerals appear in the x-rayed spectrum of granites. Practical value. The executed researches will allow us to develop recourse- and energy-saving methods of production and processing of mineral raw materials. [ABSTRACT FROM AUTHOR]

Purpose. To investigate loads in two-motor synchronous drives of tumbling mills and determine the transmission lines twist rigidity influence on twist moment distribution and its dynamic component. Methodology. Static component of displacement angle causing nonuniform distribution of loads between transmission lines, and kinematical component, which determined as cumulative error of the open toothing step and the radial beat of ring gear, was considered. The irregularity of load distribution is characterized by coefficient, which shows at how many times load of transmission line of each drive is greater than nominal load, which characterized by uniform loading of drives. The coefficient of dynamics, which shows at how many times maximal load in transmission line is bigger than nominal, is introduced for appreciating of the influence of dynamical component of load to the load of drive. Since the frequency of cinematic disturbance is determined by frequency of tumbling mill rotation, the mechanical transmission rigidity is the single factor, which has an influence on the value of dynamic component of twist moment. Findings. The analysis of data indicates that when the frequency of disturbance is small and cinematic disturbance has the same frequency as the frequency of ring gear, the resonance is able to occur when the rigidity of mechanical transmission is small and dynamic component of twist moment is able to be insignificantly low in comparison with the nominal value. When transmission rigidity is rising, the dynamic component of twist moment is rising too. When the frequency of disturbance is according to frequency of gear wheel and the rigidity of transmission is relatively big, the resonance is able to occur and twist strain is able to result in annoying load. It is shown that the limitation of dynamic load and uniform distribution of static load at drive induced by static and cinematic displacement angles of rotors can be provided by transmission drive twist rigidity reduction. Originality. The influence of mechanical transmission on static and dynamic load in two-motor drive of tumbling mill is discovered. Practical value. The feasibility of limitation of dynamic load and irregularity of static load distribution in the two-motor synchronous drives of tumbling mills due to the mechanical transmission rigidity lowering is established [ABSTRACT FROM AUTHOR]