Ukrainian Journal of Mechanical Engineering and Materials Science

6

Authors: Roman Kachmar, Roman Zhuk

Visual perception plays a crucial role in the safety of road users. However, certain conditions such as twilight, the impact of bad weather, dirty windshields, etc. have a negative impact, which in turn increase the likelihood of traffic accidents (TAs) [1]. The ever increasing number of vehicles on the road is an additional potential danger. In response to these factors work is constantly being done to modernize existing and develop new lighting devices. Vehicular headlights are firstly assigned to optimally illuminate the roadbed in order to ensure safety [2]. For this reason headlights, including their light source, are important safety elements for vehicles, and their application requires official permission. The type and location of vehicular lighting, as well as their design, light source, color and light settings are regulated by law [3]. Automakers pay sufficient attention to the fuel economy and safety of their vehicles. So for this reason automotive light sources, such as incandescent and gas-discharge (HID) bulbs, are increasingly being replaced by LED and laser diode bulbs as they provide superior lighting with lower power consumption. This in turn leads to increased vehicle safety and economy [3].

8

Authors: Andrii Dzyubyk, Volodymyr Palash, Ivan Khomych, Stanislav Hrynus

The microstructure and hardness of the weld joints of DOMEX 700 steel were investigated. As a result, the optimization of the parameters of robotic arc welding in the environment of protective gases was carried out taking into account the size of the energy per unit length. The optimum modes of welding were determined. The size of the deterioration area, where there is a decrease in hardness in comparison with the main metal, for a thickness of 6 mm is 2.36 mm, and for a thickness of 3 mm is 1.51 mm. The parameters of the robotic welding process in the arc mode in the environment of protective gases for the investigated thicknesses of the DOMEX 700 steel were recommended. As a result, the energy-saving conditions for welding performing were achieved ensuring the required technological strength.

9

Authors: Іgor Vrublevskyi

Vibratory conveying devices with electromagnetic drive are widely used in the different branches of industry. As a rule, they deal with relatively small piece goods and are not suitable for conveying of the large massive goods with high productivity. The conveying of massive piece goods needs the using of non-hopping modes of moving in which the high velocity can be reached only in the case of non-linear vibration trajectories of the conveying track, for example elliptical trajectories. Such trajectories are obtained by using of the independent drives of horizontal and vertical oscillations. Even greater velocity can be reached by using biharmonic vertical oscillation with particular optimal relations between amplitudes and phase differences of the component oscillations. These types of devices can be designed on a basis of three-mass oscillating system. Theoretical and experimental investigations show that the goods’ mass change significantly affects the vertical oscillations and weakly affects the horizontal oscillations. And at the certain relations between masses ratio and resonant tuning (ratio of frequencies of forced and natural oscillations) the vertical oscillations of active mass of two-mass vibratory device are insensitive to the change of goods’ mass. The sensitivity of vibratory conveying stability to the goods’ mass change was investigated for two-mass vibratory devices with elliptical oscillations. Three-mass oscillating systems with biharmonic oscillations in the point of view of the sensitivity to the goods’ mass changing were not considered. Analysis of different three-mass oscillating systems with electromagnetic drives of harmonic horizontal and biharmonic vertical oscillations allows determining two most preferable versions. The equations for amplitudes of components and frequencies of natural oscillations determining are derived. From the condition of insensitivity to conveying mass change the optimal relations between masses ratio and resonant tuning are obtained.

10

Authors: Andriy Kuzyshyn, Andriy Batig

The increase in motion speed of the trains moving along certain routs changes the operational conditions and interaction of the rolling stock and the track, and requires the solution of important issues related to the specifications of their maintenance, since there occur additional dynamic loads. In this case, the particular attention is paid to the interaction of the rolling stock and the railway track; to the problems of scientific substantiation of the criteria for assessing the dynamic characteristics of carriages; to the motion smoothness, traffic safety and travelling comfort; as well as to improvement of the maintenance specifications of the track and the rolling stock in the process of their operation and on the basis of scientific analysis and determination of top (safe) speeds of the trains motion. Using the three-dimensional mathematical model of the DPKr-2 Diesel train waggon, its basic dynamic characteristics were determined and analysed: coefficients of vertical and horizontal dynamics, maximum acceleration of the body both in vertical and in horizontal plane. The influence of the amplitude of vertical and horizontal obliques of the railway track on the dynamic characteristics of the Diesel train was investigated. The determination of the basic dynamic characteristics was carried out on the basis of the developed three-dimensional mathematical model of the waggon, which consists of 38 differential equations of the Diesel train motion. The simulation (solving) of the mathematical model was carried out using Maple software. The geometrical periodic equivalent obliques of the left and right rails were adopted as perturbations both in vertical and in horizontal plane. The determination of the basic dynamic characteristics of the DPKr-2 Diesel trane waggon will allow evaluating its vibro-protective properties. The determination of the coefficients of vertical and horizontal dynamics both in central and in axle leaf-spring suspension, of the maximum accelerations of the waggon body in vertical and in horizontal plane will allow carrying out the analysis of vibro-protective properties of the mechanical part of the Diesel train wagon. The obtained results may be used to define the safe interval of the Diesel train motion speeds on the track sections in the presence of vertical and horizontal obliques.

12

Authors: Vitaliy Korendiy, Viktor Zakharov

The calculation diagrams of oscillating systems and operation features of vibratory finishing machines are considered. The mathematical models of three-mass and four-mass oscillating systems are presented. The amplitude values of the oscillating masses displacements are derived. The functions of inertial and stiffness parameters optimization are formed. The optimization problems are solved with a help of MathCAD software. On the basis of synthesized inertial and stiffness parameters, the amplitude-frequency characteristics of the oscillating systems of vibratory finishing machines are formed and analyzed. In order to verify the validity of the proposed theoretical approaches, the simulation of the mathematical model of the oscillating system motion is carried out by means of numerical solving of the system of differential equations of the oscillating masses motion. The proposed structural diagrams and the operation schemes of the vibratory finishing machine, as well as the derived analytical formulas may be used by designers, researchers and technologists while improving existent and developing new equipment for vibro-finishing treatment.

15

Authors: Vitaliy Korendiy

Problem statement. The use of existing and the most widespread drives (wheeled and caterpillar one) is sometimes limited by complicated operational conditions while moving on rough terrain. The mentioned drives require a relatively flat surface to be operated effectively. A rocky or a hilly terrain imposes the demand of the use of alternative types of drives, in particular, walking ones. Purpose. In this paper, there will be proposed and analysed one of the possible structures of the walking mechanism for mobile robotic system to be used on rough terrain. Methodology. While carrying out the investigations, the structural and kinematic synthesis of the eight-bar hinge-lever walking mechanism has been performed using the well-known methods of the Theory of Machines and Mechanisms, in particular, the method of closed vector loops. In order to conduct experimental investigations and simulation of the mechanism motion, the applied software SolidWorks and MapleSim has been used. Findings (results). The structure and geometrical parameters of the eight-bar walking mechanism have been synthesized with the aim to ensure the required trajectory and kinematic characteristics of the supporting foot motion. Originality (novelty). The analytical dependencies describing the trajectory of each hinge of the analysed walking mechanism have been derived and the kinematic optimization synthesis problem has been solved. This allowed to substantiate of the mechanism’s geometrical parameters and to analyse its kinematic characteristics. Practical value. The proposed structure of the walking mechanism can be effectively used in various mobile robotic systems and in transporting and technological machines in order to ensure the possibility of their use on rough terrain where there is no ability to use wheeled and caterpillar drives. Scopes of further investigations. While carrying out further research, it is necessary to analyse the influence of the weight coefficients on the solution of the optimization problem, as well as to take into account the necessity of changing the step length and the foot lifting height during the process of walking according to the surface obstacles sizes.

8

Authors: Andriy Pogrebnyak, Volodymyr Pogrebnyak

The article aims to determine the peculiarities of macromolecule deformation behavior under conditions of a jet-shaping head that would allow to solve the issue related to the mechanism of increasing water-jet cutting power with polymer additions. The roles of longitudinal and transverse velocity gradients in the manifestation of distinctive features of polymer solution flows are analysed. In converging polyethyleneoxide solution flow macromolecules are forced by a hydrodynamic field to rather strong stretching that causes the dynamic structure formation in solutions. There have been studied experimentally velocity fields and their gradients as well as the degree of macromolecule unrolling under pattern conditions of a jet-shaping head in polyethyleneoxide solutions flow. In converging polymer solution flow macromolecules are forced by a hydrodynamic field to rather strong (~ 60 % and more) stretching that causes the field restructuring. The determined regularities of macromolecules behavior in the flow under conditions of a jet-shaping head and manifested in this case effects of elastic deformations have paramount importance in understanding the mechanism of “anomalously” high cutting power of water-polymer jet. The work for the first time makes it possible to explain the nature of increased water-jet cutting power with polymer additions when cutting food products. Understanding the nature of increased cutting power of water-polymer jet will make it possible to develop recommendations on choosing regimes for water-polymer jet processing of food products by cutting.

8

Authors: Petro Koruniak, Iryna Nishchenko, Volodymyr Borovets

The urgent problem of automatization of the process of products transportation with a help of vertical chutes under the influence of gravitational forces using elastic elements is considered. The interaction between the object being transported and the elastic elements is defined. Their mutual influence on the transportation speed is determined depending on the contact parameters. The analysis of the object transportation speed changing depending on friction and on the zone of their mutual contact is carried out.

8

Authors: Roman Kachmar , Juriy Vasyuhnyk

To the greatest extent, the indicators of the motor vehicles being in the normative technical state are influenced by the operational conditions, which, in turn, are characterized by road, relief (terrain) and transport conditions. The transport conditions of large cities of Ukraine are characterized by the intensive increase of motor transport, especially individual (private) one, on the street-road network of the city caused a number of problems, such as increased waste of time needed for a trip, increased number of forced stops, increased number of emergencies and road-traffic accidents, the occurrence of traffic jams, chemical and noise pollution of the environment. As the special investigations indicated, the volume of traffic has increased by 1.5…1.8 times in comparison with the data of ten years ago [1]. All this caused the necessity to substantiate the rational use of the power of the motor vehicles engines and to control their ecological indexes in order to reduce the negative influence on the environment. While evaluating the toxicity of the motor vehicles engines, two fundamentally different methods of investigations are being used: testing on steady-state operating conditions with constant parameters of the engine and testing on transient operating conditions when the input parameters are being changed. For the transient conditions, the main conditions of the motor vehicles motion have been identified: motion in the conditions of the city and motion out of its borders. Each of the conditions is characterized by the differences in the percentage of toxic components in the exhaust (burnt) gases. While developing the technique of determination of ecological indexes and parameters of fuel economy (saving) for motor vehicles, a large number of factors, which varies depending on the operating conditions, are considered. This is expedient in the case when the operating conditions are very different considering the typical motion conditions in the region and the several aspects that affect the fuel consumption. One of the main reasons for this is the unsatisfactory state of planning, accounting and standardization of the efficiency of the motor vehicles use. In this approach, the operation indexes are estimated based on not always impartial reporting and statistical data, so the standards are not an impartial factor or a model for the motor vehicles operation. These circumstances substantiate the urgency of the subject of research. While carrying out these investigations, the preliminary analysis of the motion conditions of the motor vehicles in different operating conditions is conducted and the peculiarities of the existing driving cycles of different countries of the world are considered. In order to ensure the determination of the motion conditions of motor vehicles in the conditions of the city of Lviv, the technique of investigations carrying out was developed on the basis of available means. The results of changing the conditions of the motor vehicles motion in the conditions of the city of Lviv were obtained taking into account the motion speed of the motor vehicle, the rotation frequency of the engine crankshaft, the instantaneous fuel consumption and the amount of consumed air. According to the results of the experiments carried out, the main features of the operational conditions of motor vehicles motion in Lviv were determined, the driving cycle for testing the motor vehicle in the conditions of Lviv and the method of comparative analysis of existing and improved driving cycles were developed. The analysis of indexes of existing and developed driving cycles is carried out and the expediency of use of the developed driving cycle is substantiated.

10

Authors: Volodymyr Biloborodchenko

The problem of applied diagnostics, statistically rigorous by the proposed model analogue, running stressed-deformed state of the main (trunk) shell is studied by the method of magnetic coercimetria. The relationship between the parameters of the loop of magnetic hysteresis is stochastically related with structural and mechanical state of the material of the pipeline wall and with the rest of equal conditions allows to effectively detect the zone of concentration of local stresses on the stage of their forming and development (propagation) on the basis of quantitative comparative analysis of their value with calculated equivalent mechanical stresses in principal (main) planes for particular pipe material considering that the operational stresses shouldn’t be larger than 30–50 %of the yield limit. The hypothesis H0 about the possibility of description of the measurement data of the stressed mechanical state by the magnetic-static method of coercimetria is made taking into account the peculiarities of disturbances caused by the operation of electric chains of the measuring apparatus during its metrological calibration. This hypothesis confirms that the arcsine function is a law of distribution probability density of the measured values of the coefficient of magnetic anisotropy as a response of the mechanical state of the pipe shell, that the parameter Q equals 0.95 on the confidence level and substantiates the evaluation of frequency of the influencing equivalent stresses in the whole range of loads applied to the shell by the inside normalized variable pressure. On the basis of corresponding scaling and renormalization of investigative values of the coefficient of magnetic anisotropy, the technique of determination of the level of mechanical stresses in the object of diagnostics is developed and the statistically rigorous compatibility in the certain range of influence of internal pressure in the pipeline is demonstrated using the results of preliminary metrological calibration of coercimeters obtained for different pipe steels.

10

Authors: Ihor Kuzio, Oleksandr Zhytenko, Yurii Zalutskyi

In this article, some methodological statements of the formation of mathematical models in the problems of machine dynamics are elucidated. The presence of a cushioned freight in the form of the fastened vehicle complicates the system, so that the equations describing its oscillations are too complicated and unsuitable for practical usage. It is shown that with all the complexity of the research object, it is expedient to form the mathematical model at the level of the design diagram (model) with a relatively small number of degrees of freedom. The peculiarities of mathematical modelling of the motion processes of specialized articulated vehicles for transportation of cars, namely, formation of the design diagram (model), making the necessary assumptions, choosing the independent coordinates and writing down the second-order Lagrange equations describing the system oscillations, are presented. While modelling, the most typical case, namely, the motion over the unit prominence (road shock), the effect of which on the wheels of the articulated vehicle is of the impact type, is considered. The choosing of the initial perturbation in the form of a unit impact is caused by the possibility of obtaining an impact characteristic, which is defined as the reaction of the system on the δ-function. In addition, under the impact action, it is possible to carry out the direct visual analysis of non-interfered single-frequency oscillatory processes, which allows to quickly obtain the approximate express-evaluation of the amplitude values of the process, frequencies of oscillations, as well as the oscillations damping decrement of the two-section articulated vehicle, if it is necessary. The mathematical model of the articulated vehicle consisting of a tractor and a semi-trailer in the form of a linear system having 9 degrees of freedom is developed. It consists of three cushioned masses, namely, the frame of the truck tractor, the frame of the semi-trailer and three non-cushioned masses, which are axles with wheels as an assembly. Both sections of this system are connected by the saddle-coupling element that is not absolutely rigid. While moving, the frames of the truck tractor and of the semi-trailer performs oscillatory motion in the vertical plane and angular oscillations about an axis passing through the centre of masses. The axles with wheels in the assembly oscillate only in the vertical plane. The peculiarity of the model is that the elastic and damping properties of the suspension of vehicle fixed on the semi-trailer are taken into account. The solution of the mathematical model allows to obtain the impact characteristic, to calculate the amplitude-frequency characteristic and to obtain the required (unknown) values of the root-meansquare accelerations of the non-cushioned masses. The technology of systemic consideration of the problems of formation of mathematical models in the form of block diagrams (structure charts) which are equivalent in dynamic relation to the systems of automatic control is offered.

30

Authors: Bohdan Diveyev

The main aim of this study is to predict the elastic and damping properties of composite laminated plates. Some approximate methods for the stress state predictions for laminated plates are presented. For simple uniform bending and transverse loading conditions, this problem has an exact elasticity solution. This paper presents a new stress analysis method for the accurate determination of the detailed stress distributions in laminated plates subjected to cylindrical bending. The present method is adaptive and does not rely on strong assumptions about the model of the plate. The theoretical model described here incorporates deformations of each sheet of the lamina, which account for the effects of transverse shear deformation, transverse normal strain-stress and nonlinear variation of displacements with respect to the thickness coordinate. Dynamic and damping predictions of laminated plates for various geometrical, mechanical and fastening properties are defined. The comparison with the Timoshenko beam theory is systematically done for analytical and approximation variants. The values of damping are got at a bend in three- and five-layered plates. For the threelayered plates the equivalent beam of Timoshenko exactly approximates a “sandwich” (with a soft damping kernel) dynamic properties of sandwich in a wide frequency range. For a plate with soft external layers the equivalent beam needs to be found in every frequency range separately. A hard bounded layer multiplies damping in a plate with soft external layers, however only at higher frequency of vibrations. For the high-frequency vibrations of plates the anomalous areas of diminishing of damping (for sandwiches) and increase are got for plates with soft covers. At the moderate amount of approximations the exact divisions of tensions are got in the layers of plates, thus the stresses continuity and surface terms are approximated exactly enough. Unlike the widespread theories of plates with the terms set a priori on surfaces (as a rule levels to the zero tensions) the offered equations allow to satisfy and complicated boundary conditions, instead of only free fastened plates. It allowed to explore the row of important examples for plates fastened in a hard holder and to explore influence of not only plates but also construction of holder on damping.

8

Authors: Mykola Karpenko, Marijonas Bogdevicius, Olegas Prentkovskis

In the article the review of the problem of improvement of technology of high pressure hoses cutting on the hand cutting machines is analyzed. Different methods of cutting of high pressure hoses into the billets are overviewed and the quality of edge cuts of hoses is analyzed. The comparison of treatment on automatic cutting machines and on hand cutting machines is carried out. Different experimental techniques of improvement of the quality of edges cutting of high pressure hoses are presented. On the basis of experimental method, a new cutting technology which consists in maximally close fixation of high pressure hoses to the cutting disc is proposed. In the basic design of the hand cutting machine, the only supports are provided, so that the cutting of the edge section of high pressure hoses causes the metal braid loosening. The proposed technology excludes the scrolling and bending of high pressure hoses during cutting, so that the loosening of metal braid is also excluded. In the paper it is shown that the scheme of distribution of cutting forces during the cutting of high pressure hoses is presented and the mathematical model of determination of normal and tangential cutting forces is formed. With a help of tensiometric table the values of components of cutting forces during free and fixed cutting of high pressure hoses were defined and their comparison was performed. As a result of the use of this technology the edges of the cut off high pressure hoses meet the necessary requirements without using of complicated technological processes.

10

Authors: Sergii Maksimov, Oleg Oleinik, Anatoliy Gavrilyuk

Investigations on the development of a basic technology of the shielded-gas mechanized arc welding of strengthening structural elements which are used in repair of main gas pipelines were carried out. It is shown that the advanced welding wires Sv08G2S, Е71Т-1, DW-50, DW-A55 are in compliance with the requirements for providing the necessary level of mechanical characteristics, impact toughness of weld metal, content of diffusive hydrogen in the deposited metal and can be recommended for application in the further testing of technology for repair of the operating pipelines under the field conditions. The carried out works resulted in the working out of documentation on the technology of mechanized arc welding in shielding gases in repair of main gas pipelines of Ukraine.

10

Authors: Andrii Dzyubyk, Liudmyla Dzyubyk, Yaroslav Zinko, Stanislav Biruk

The design of banding shells of rotary units is analyzed. It is shown that combined welding and cast manufacturing of bandings is used in the case of large structural sizes. The basic materials (30, 35, 25 HSL and 30 HML), being used in this process, are characterized by the tendency of forming of hardening structures due to the thermal cycle of welding. As a result of this, the cracks in the heat-effected zone, which lead to the destruction of the connection under the influence of welding residual stresses. The analysis of literature sources has shown that the usage of electroslag welding is perspective during the manufacturing and welding of operational cracks. Thus it is important to define the correct parameters of the welding conditions. In the case of electroslag method they are different from the arc methods and are characterized by the larger amount. In the paper the technological process of welding of banding (tread) ring with the external diameter of 4600 mm, wall thickness of 300 mm and wideness of 500 mm, which is made of steel 35. The defining of regime parameters is made using the following recommended techniques: taking into account the chemical composition of the basic metal; according to the nomogram depending on the ratio of the thickness of the metal to the number of electrode wires; using the calculation (design) method according to the conditions of electroslag welding of the banding. Taking into account the tendency of the steel 35 to cracks forming (cracking), the evaluation of the structure and phase composition and mechanical properties of metal of heat-effected zone of the weld. In order to define the microstructure, the cooling rate of the metal in the range of structural transformations was determined and the diagram of anisothermal decomposition of austenite was used. The technique of determination of the metal cooling rate as a result of the influence of thermal cycle of electroslag welding is proposed in the paper. It is based on the usage of special nomograms which characterize the specific features of the process being studied. The cooling rate equals w= 0.1876 degrees per second when using the developed process parameters. Also the investigation of temperature distribution in the cross-section of the weld has been carried out. It is shown that there are no significant deviations of temperature when using the proposed regime parameters. This influences the reduction of the level of residual stresses along the thickness of the weld. The analysis of the diagram of austenite transformation has shown that the structure of the steel 35 in the initial state is ferrite one with the mixture of pearlite and bainite. As a result of welding carrying out the structure will have a similar composition with slightly larger content of perlite and bainite. It was defined that their content in the heat-effected zone is as follows: 39 % for ferrite, 61 % for the mixture of perlite and bainite. At the same time, the investigated technology of electroslag process ensures the slow heating and cooling of the areas around the weld and obtaining of satisfactory mechanical properties of the metal. Therefore, the combined usage of existent techniques of regime parameters determination is expedient. Also it is necessary to carry out the verification of physical and chemical properties of the metal of heat-effected zone in order to prevent the formation of hardening structures.

10

Authors: Petro Koruniak, Vladyslav Shenbor, Vitaliy Korendiy, Anatoliy Bezpalov, Volodymyr Brusentsov

The operation of hopper devices, which are used in industry, civil engineering, agriculture and transport, is analyzed on the article. The external factors, which influence the process of charging, storing and discharging of loose cargo (freights) from hopper tanks, are overviewed. The subject of research of presented paper is the improvement of mechanisms of fracturing of products hangs-up (bridges) in hoppers at the stage of designing and setting up of hopper devices. In order to solve the stated problem the schemes of bridges fracturing and the structures of devices for debarment of products bridging and their uniform outflow from the hopper tank are proposed. The proposed schemes are based on the principles used in development of vibratory machinery with mechanical, cam and electromagnetic vibratory principles of structures forming. For cam spring device of bridges fracturing the technique of calculation of stiffness of elastic system and of the necessary forces for performing of technological process of bridges fracturing is presented and the recommendations for choosing of the stiffness of the system of elastic elements are suggested. For the hoppers with spring and electromagnetic blocks of bridges fracturing and of metered (batched) feeding of products the structural diagrams of devices are presented and the recommendations for usage of various modifications of devices are suggested. The influence of parameters of flat spring elements on the efficiency of devices operation is overviewed. The structural diagrams of devices with one-cycle and two-cycle electromagnetic vibration exciters and the modifications of elastic systems are considered. the structural diagram of the production prototype of the hopper feeder is presented. The materials of the article, the proposed structural diagrams, the operation scheme of the hopper feeder and the derived analytical formulas may be used by designers, researchers and technologists while improving of existent and developing of new devices.

22

Authors: Bohdan Diveyev

This study aims to predict the sound transmission properties of composite layered plates structures in the lower frequency range. In present paper a novel procedure to derive the sound isolation parameters for layered plates is under discussion. This paper presents a new stress analysis method for the accurate determination of the detailed stress distributions in laminated plates subjected to cylindrical bending. Some approximate methods for the stress state predictions for laminated plates are presented here. The theoretical model described here incorporates deformations of each sheet of the lamina, which account for the effects of transverse shear deformation, transverse normal strain-stress and nonlinear variation of displacements with respect to the thickness coordinate. The main advantage of the present method is that it does not rely on strong assumptions about the model of the plate. Comparison with the Timoshenko beam theory is systematically made for analytical and approximation variants. The geometrical and mechanical parameters dependent frequency response functions and damping are presented for an arbitrary layered beam. The effective stiffness constants of equivalent to lamina Timoshenko beam (TB) and their damping properties have been determined by using a procedure based on multi-level numerical schemes and eigenfrequencies comparison. Numerical evaluations obtained for the vibration of the equivalent TB have been used to determine the sound transmission properties of laminated composite beams with the system of dynamic vibration absorbers (DVA’s). The optimization of beams – DVA’s system sound absorption properties is performed in the low frequency range. The results have shown that the presence of a DVA causes a decrease in the sound transmission in the low-frequency range. The extension of the present approach to various layered plates with various DVA’s systems will be performed in order to obtain optimal sound insulation.

10

Authors: Andriy Kozak

Automatic dosing system for loose materials is widely used in construction, food and pharmaceutical industries to prepare various mixtures. The main criterion for optimization of such systems is the accuracy of dosing of each component of the mixture, which depends on the speed component dosing and other process factors. Technological requirements for product quality in production and the high cost of individual components of the mixture strictly regulate the developers of the automated system loose materials size dosing errors. Ensuring compliance with the maximumpossible mix recipe requires dosing of each component with high accuracy, which is a daunting task for engineers. Precision dispensing in automated systems is a function of the large number of systematic and random factors: size, shape and relative position of individual particles of the material; coupling coefficient of each other and of the structural elements of the dispenser; relative humidity of material dosage and indoor air; the height of the fall of the material in the receiving container; the value of the dispenser tilt to a level of horizon; electromechanical vibration and noise, etc. Developed simulation model of frequency-controlled electric screw feeder that is different from the known one facts that modeling of screw feeder is considering mass “falling pillar” which is constantly changing as the accumulation of material in the hopper.

10

Authors: Alexander Оrgiyan, Anna Balanyuk, Vladimir Kobelev, Ivan Tvorischuk

On the basis of precision theory we propose the method of computation of static and dynamic errors of cross-sectional shapes of holes in fine boring of smooth and stepped holes. We consider particular cross-sectional shape errors caused by such factors: – Error of the tooled hole form caused by the axis hope displacement in the workpiece relative to the spindle axis; – Error of the tooled hole form caused by the hole out-of-roundness in the workpiece; – Error of the tooled hole form caused by unevenness of the cutter radial compliance at the angle of spindle rotation. According to time characteristics the errors can be divided into static with frequency substantially less than the lowest natural frequency of the process system, and dynamic, caused by vibrations. Static error rate is usually a multiple of the spindle speed. The computations of deviations from the roundness of the cross section caused by vibrations are determined by computing the amplitudes of forced vibrations. Computations of individual static errors based on the average values of compliance, the material being processed and the processing mode are reduced to construction of nomographs for various materials. Dynamic errors are determined by computation of forced vibrations amplitudes on the basis of systems of ordinary differential equations describing the vibrations of a machine closed dynamic system. These equations allow to compute the amplitude of the forced vibrations of smooth and stepped boring bars. A distinctive feature of the computations for multiple tooling is allowance for mutual influence of excitations arising at each step of a boring bar. It is assumed that at multiple tooling each of the working cutters creates its own errors, the values of which are found by the nomograms for single-cutter tooling. Full tooling error at each step caused by some source of error is determined as the sum of the errors: of both, own and additional, caused by all working cutters. Additional errors can be found through coefficients of influence through dividing by the respective cutter's own compliance and through multiplying by the appropriate factor of influence. We obtained results of computations and experiments of the dependence of the total error on the ratio of the boring bar steps lengths. Analysis of roundness charts of the bored holes shows that vibrations can be a factor largely determining the shape of the cross section of the hole. Experiments have shown that when the rotation speed changed the excitations of the spindle poles changed too. Under unfavorable excitation frequencies the tooling errors increase by 1,5–2 times. The study results allow us to compare the two most common ways to reduce the errors caused by elastic deformations: the use of the dynamic damper and the processing of holes in two runs. The experimental results confirm the non-monotonic dependence of the amplitudes of forced vibrations on the ratio of the boring bar steps lengths.

20

Authors: Yuri Chovnyuk, Yuri Gumeniuk, Mykhailo Dikterjuk

Most authors have ignored the effect of rotatory inertia and shear deformation. This practice is justified for slender flexible arms. According to the Timoshenko beam theory, the deflection due to shear force and rotatory inertia should be taken into account in modelling for high speed and high precision requirement when the ratio of the cross-sectional dimensions to length increases. Based on Hamilton’s principle and Timoshenko’s flexible beam theory, the dynamic model of a single non-slender flexible link is derived, and it is shown that the elastic motion is governed by a pair of coupled partial differential equations with coupled boundary conditions. Then the abstract form of the dynamic equations is studied, and the properties of the spectrum of the elastic operator appearing in the evolution equation are given. Furthermore, the eigenvalue problem of the elastic operator is solved in explicit form. The formulation and well-posedness of the state-space equation, as well as the transfer function of the dynamic control system of the non-slender flexible link, are studied by spectral analysis. Spectral analysis is used to study the well-posedness of the dynamic control system. The tracking control problem is studied and a feedback control scheme that controls the rigid-body motion and elastic behaviors simultaneously is derived based on a n-modal model. Closed-loop configuration of a control system, equivalent circuit of a dc-motor and the overall system block diagram are proposed. The stabilization of the closed-loop system is studied analytically. Finally, the tracking control problem is studied, a stabilizing feedback control law based on a n-modal model to suppress vibrations of the flexible link is derived, and the necessary and sufficient conditions that can guarantee the stability of the closed-loop system, are given. Simulation results are given as well.

8

Authors: Serhii Hromniuk, Ihor Hrytsai

The relevance of the problem which is solved in this article has been substantiated. In modern machines and equipment, rotary motions which cannot be implemented without gear wheels and gear trains are always present. Attainment of high performance of a machine – increase in loading with simultaneous increase in speed, increase in transmitted forces and moments, decrease in noise during operation, ensuring high indexes of failure-free performance and longevity of a machine – depends on precision in manufacturing the gear wheels and gear trains. These requirements to modern machines are put simultaneously with improvement of technology of their manufacturing and with creation of new effective methods of machine parts working. A new effective method of radial-circumferential (RC) gear cutting by disk-type cutting tool under the conditions of continuous generation (revolving) around is described; this way enables us to considerably reduce the expenditures for expensive and complicated cutting tools, to increase productivity of the process, and to increase precision of gear wheels. However, for application of this method in the course manufacturing, it is necessary to develop a technique of prediction of the precision of the gear cutting; such a technique being able to serve as a basis of substantiation of the choice of regimes of gear cutting. Principles of the mathematical model of cutting force of gear cutting, i.e. a model which is based on modelling of parameters of shearings made by a disk-type milling cutter, are presented in this article. This mathematical relation takes into account the intensity of deformation of the layer which is being removed and the strength of the material which is being machined; the model also enables us to determine the force on individual blades and its total value on all the active teeth in RC-method at any instant of time of milling as a function of the turn angle of the cutting tool. Analysis of cutting force has indicated that in one revolution of a milling cutter the cutting force varies according to aperiodic regularity, and its peak values are considerably less than the force of gear-tooth milling by a hobbing cutter under the same initial conditions. Since the disc-type gear milling cutter, as compared with the hobbing cutter, is considerably more sensitive to elastic deformations, the cutting force can essentially influence the error of gear cutting of ring gears. Proceedings from this, the influence of primary errors and that of elastic deformations which are caused by variable cutting force in the cycle of revolution of the milling cutter and formation of gears on the error of the working is investigated. Laws of the influence of radial, axial, and torque deformations of the elastic system of a machine on the deviations of parameters of the teeth from their rated ones and on the error of profiles in the process of gear milling according to radial-circumferential method are presented. The enhance of precision of tooth cutting and reduction of the total error becomes possible due to the choice of such regimes of cutting (first of all, axial feed) under which the necessary precision of the chosen parameter of precision, in particular, profile error, can be attained.

10

Authors: Volodymyr Malashchenko, Oleh Strilets, Volodymyr Strilets

The article deals with problem of speed change management in engineering, i.e., hoisting, building, road and land reclamation machines, cars and tractors, machine tools and other equipment. The review of the methods and devices for stepped, steppless and combined speed change process management have been performed. Their major disadvantages have been identified. Among others, main disadvantages of stepped speed management devices are the complexity of design, their large material consumption, the emergence of dynamic loads during the transition from one speed to another, even in case of synchromesh using. Continuously variable speed devices have intense components wear due to the use of friction connections like brakes or lock-up clutches. The authors lead to the conclusion about the need for new devices of speed change management to remove, or at least decrease, identified deficiencies. New devices suggested for speed changes management via epicyclic gear trains with a closed circuit hydrosystem. Those new constructions are supposed to remove abovementioned shortcomings and can be the basis and foundation for new devices creation and their further research.

14

Authors: Vitaliy Korendiy

Problems and prospects of using the walking mode for producing motion of robotic systems are considered. Advantages and spheres of the use of mobile robotic systems equipped with walking movers are substantiated. Preferences of cyclic (lever) walking mechanisms are analyzed. The kinematic parameters of four-bar crank-rocker walking mechanism, constructed on the basis of Chebyshov-Umnov mechanism, are accepted as the subject of research. The process of motion of the supporting foot of the walking mechanism is accepted as the object of research. The main aim of the investigation consists in carrying out structure and kinematics analysis of the mentioned mechanism with further derivation of analytical dependencies for calculating kinematic parameters of the supporting foot motion. The special features of the structure of four-bar walking mechanism and theoretical foot loci (paths) are considered. The form of the most reasonable path for further research is established. As a result of carried out structure analysis, it is ascertained that the mechanism consists of two structural groups: that of the first class and that of the second class second order first type. As a result of kinematics analysis, the analytical expressions for calculation of coordinates of the supporting foot hinge of the walking mechanism depending on geometric parameters of the mechanism and the angle of the crank rotation are deduced. The prospects of further investigation under the themes of the paper are analyzed. In particular, the goal function, which may be used for further optimization of structural parameters of the mechanism, is considered and the use of applied software for solving optimization problem is suggested. The optimization problem consists in evaluating such geometric parameters of the walking mechanism which allow the motion of the supporting foot in accordance with the prescribed (specified) path.

16

Authors: Bohdan Diveyev

Passive, broadband targeted energy transfer refers to the one-way directed transfer of energy from a primary subsystem to a nonlinear attachment; this phenomenon is realized in damped, coupled, essentially nonlinear impact or particle dynamic vibration absorber (DVA). An impact damper is a passive control device which takes the form of a freely moving mass, constrained by stops attached to the structure under control, i.e. the primary structure. The damping results from the exchange of momentum during impacts between the mass and the stops as the structure vibrates. A particle-based damping system can overcome some limitations of ordinary DVA by using particles as the damping medium and inter- particle interaction as the damping mechanism. Large damping at such family constructions of DVA’s does not bring to destruction an elastic DVA element over in critical cases, when working frequency approaches own frequency of DVA, or when the transitional process of acceleration of rotating machines is slow enough and DVA’s has time to collect large amplitudes of vibrations. The primary structure is modelled as a spring-mass system. In this paper, an efficient numerical approach based on the theoretical-experimental method is proposed to maximize the minimal damping of modes in a prescribed frequency range for general viscous tuned-mass systems. Methods of decomposition and numerical synthesis are considered on the basis of the adaptive schemes. The influence of dynamic vibration absorbers and basic design elastic and damping properties is under discussion. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in sinusoidal forced rotating system. It is found that the buffered impact damper not only significantly reduces the accelerations, contact force and the associated noise generated by a collision but also enhances the level of vibration control. The interaction of DVA’s and basic design elastic and damping properties is under discussion. One task of this work is to analyze parameters identification of the dynamic vibration absorber and the basic structure. The discrete-continue models of machines dynamics of such rotating machines as water pump with the attachment of particle DVA’s and elongated element with multi mass impact DVA’s are offered. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in harmonic stochastic and impact loaded systems.