TECHNOLOGY OF PRODUCING REINFORCED CONCRETE COLUMNS OF CIRCULAR CROSS-SECTIONAL AND INVESTIGATION OF THEIR STRAIN-STRESS STATE AT TRANSVERSE-LONGITUDINAL BENDING

The paper presents a method of producing Circular Cross-Section Columns (CCSC), which can provide sufficiently precise dimensions, with longitudinal reinforcement securely fixed in special plugs. An investigation procedure for determining the capacity of CCSC at all the stages of their loading with eccentric pre-stressing has been presented. Based on the conducted experimental work, load carrying and deformation parameters of the strain-stress state of reinforced concrete CCSC have been obtained. The investigation results make it possible to define calculation prerequisites and fracture criteria of the deformation method of calculating compressed-bent elements of CCSC at transverse bending and reinforcement deformation below the yield point

EXTERNAL ROLLING OF A POLYGON ON CLOSED CURVILINEAR PROFILE

The rolling of a flat figure in the form of an equilateral polygon on a curvilinear profile is considered. The profile is periodic. It is formed by a series connection of an arc of a symmetrical curve. The ends of the arc rely on a circle of a given radius. The equation of the curve, from which the curvilinear profile is constructed, is found. This is done provided that the centre of the polygon, when it rolls in profile, must also move in a circle. Rolling occurs in the absence of sliding. Therefore, the length of the arc of the curve is equal to the length of the side of the polygon. To find the equations of the curve of the profile, a first-order differential equation is constructed. Its analytical solution is obtained. The parametric equations of the curve are obtained in the polar coordinate system. The limits of the change of an angular parameter for the construction of a profile element are found. It is a part of the arc of the curve. According to the obtained equations, curvilinear profiles with different numbers of their elements are constructed

Research of a contact stresses in swivel elements of flexible shaft in screw conveyor for transportation of agricultural materials

Saabunud / Received 12.03.2022 ; Aktsepteeritud / Accepted 28.04.2022 ; Avaldatud veebis / Published online 28.04.2022 ; Vastutav autor / Corresponding author: Jüri Olt ; [email protected] paper presents the new design of the rotating part with ball-bearing swivel joints between its sections for flexible screw conveyors. The new design provides for the improvement of the operation efficiency and loading capacity, the enhancement of the technological capabilities and the reduction of the admissible curvature radius. The contact stresses in the swivel element as the most loaded area in the rotating part have been analysed. It has been established that the maximum contact stresses arise at the points of contact between the ball and the flat surface of the slot in the cylindrical bushing. The recommended design limitation range for the cavity cone angle is within about 30–50. The relation between the loads and the stresses depending on the operating conditions has been modelled with the use of computer modelling. The comparison of the computer modelling results and the obtained calculation data has proved that the difference between the respective values varies within the range of 11–26%

Determination of optimal parameters of hinged operating elements of screw conveyers

The relevance of the research lies in the need to improve, develop new designs and determine the optimal structural and kinematic parameters of the hinged sections of the screw working bodies of the conveyors, in order to obtain better functional and operational characteristics of the process of transporting loose and lumpy materials and granular fertilizers. It is necessary to improve and develop a new designs and determine optimal design and kinematic parameters of hinged sectional operating elements of screw conveyers, which can provide the improvement of functional and operating characteristics of the process of transporting loose materials. Therefore, the purpose of the research was to improve the operational performance of flexible screw conveyors by developing and determining the optimal parameters of hinged flexible screw sectional working bodies for overloading bulk materials along curved transportation branches. The research was carried out using the methods of the theory of mathematical and computer modeling. the method of mathematical planning of the experiment. The article presents new designs of hinged screw working bodies and substantiates their optimal parameters for ensuring the movement of loose materials along curvilinear routes. The relationship between the magnitude of the torque that occurs between the loaded screw sections and their spatial arrangement is determined. Analytical dependences were obtained for the stiffness conditions of a separate section with a hinged connection depending on the load and design parameters of the conveyor. It has been established that the angular displacement of the sections according to the dependence established in the state allows to significantly (up to 4-5 times) reduce the amplitude of the change of the torque of the drive, and also lowers its maximum value. It was proved that in the pushing mode, energy consumption is 1.06...1.4 times higher than in the pulling mode. The practical significance of the results lies in the ability to choose the optimal structural, kinematic and technological parameters of the developed sections of the screw working body for transporting loose or lumpy materials and mineral fertilizer

Design development and study of an elastic sectional screw operating tool

The results of an elastic sectional screw operating tool development and its production technique are presented in the article under consideration. The operating tool has been made to fix the elastic sections, providing the transportation of bulk materials of agricultural production, in order to ensure their minimal damage and the process minimal power capacity. The article presents constructed regression dependencies and response surfaces for the effects of the design, kinematic and technological parameters of a sectional screw operating tool on power consumption and the damage rate of grain material in the process of its transportation. As the result of the conducted experimental research, authors came to a conclusion that the arrangement of an elastic auger without a gap between its peripheral part and the inner surface of the guiding tube significantly reduces vibrations in the process of conveying bulk material

Rolling of a single-cavity hyperboloid of rotation on a helicoid on which it bends

The bending of a single-cavity hyperboloid with rotation while maintaining the rectilinear generator is considered. The resulting bending surfaces are a plural of open skew helicoids, including partial cases of oblique closed and open ordinary helicoid s. The parametric equations for the continuous bending of these surfaces are established by changing the angle between the straight line and its axis. The possibility of pure unrolling of a hyperboloid along a helicoid from the set of its bends with linear contact along a common rectilinear generator of both surfaces is shown. Using the obtained equations, the surfaces are constructed and the images of hyperboloid and helicoid with the common rectilinear generator of their contact are shown

Theory of Movement of the Sugar Beet Tops in Loading Mechanism, Taking into Account the Influence of the Air Flow

A new design of the haulm harvester with an improved loading mechanism has been developed, which is made in the form of a centrifugal thrower that receives the entire volume of the cut sugar beet tops, as well as an unloading pipe, the end of which is at the level of the vehicle, moving beside the haulm harvester. To substantiate the rational parameters of this loading device, a mathematical model of the movement of a particle along the thrower blade and its exit from the blade was developed in order to simulate further movement along the inner surface of the cylindrical part of the casing and its straight part before entering the vehicle. The resulting differential equation for the movement of a haulm particle along the thrower blade takes into account the influence of the airflow created by the rotation of the thrower, the blades of which capture and accelerate the air in the closed space of the cylindrical casing. The indicated differential equation includes the basic design, kinematic, and power parameters affecting the flow of the studied loading process of the tops. The solution of these differential equations on a PC made it possible to obtain graphic dependencies, with the help of which the rational parameters of the working bodies of the loading mechanism of the haulm harvester were substantiated. As calculations show, an increase in the angular velocity of rotation of the thrower and the length of its blade leads to an increase in the absolute velocity of the haulm particle M from the end of the blade. Thus, by increasing the length of the thrower blade from 0.1 m to 0.35 m and its angular velocity from 10 s−1 to 40 s−1, the absolute velocity increases from 1.2 m s−1 to 16 m s−1. At an angular speed of rotation of the thrower equal to 10 s−1, an increase in the airflow velocity from 5 to 35 m s−1 leads to a smooth linear increase in the relative velocity of particle M, as it moves along the blade of 0.67 to 0.78 m s−1. For a higher angular velocity of rotation of the thrower, equal to 20 s−1, the growth curve of the relative velocity of particle M is more intense at an airflow velocity in the range from 5 to 25 m s−1, approaching the linear law at an airflow velocity of more than 25 m s−1. In this case, the relative velocity varies from 0.9 to 1.4 m s−1

Theoretical Study of the Motion of a Cut Sugar Beet Tops Particle along the Inner Surface of the Conveying and Unloading System of a Topping Machine

One of the most delicate operations in the sugar beet harvesting process is removing the tops from the heads of the root crops without any mechanical damages. The aim of this study is to improve the design of the conveying and unloading system of the sugar beet topper machine. In this paper, a mathematical model of the motion of a cut beet tops particle M, along the conveying and unloading system, has been developed to support the evaluation of kinematic and design parameters, depending on the rotational speed of the thrower blade, the air flow speed, the required ejection speed of particle M, and the position of the trailer that moves alongside the harvester. It has been established that increasing the speed Va of the top particle M, which has left the end of the blade of the thrower, leads to an increase in the arc coordinate S(t) of its movement along the cylindrical section of the casing. Within the range of the speed change from 4 m·s–1 to 8 m·s–1, the value of the arc coordinate S(t) increases by 1.4 times during time t = 0.006 s. Moreover, a rapid decrease in speed V is observed with an increase in the length x of the discharge chute

Research of the Possibilities to Improve the Quality of Potatoes Harvesting by Including an Experimental Heap Leveler-Distributor in the Design of Harvesting Machines

Improving the quality indicators of the operation of potato harvesters under difficult soil and climatic conditions is an urgent scientific and practical task. The paper reflects a research of the impact upon the quality of operation of two kinds of potato diggers of an experimental design for additional levelling of a heap (mass of soil, potato tubers, plant residues, etc.) on the conveyor. This device evenly distributes the potato heap along the plane of the main rod elevator, improves the separation conditions, reduces the total loss of tubers from 2.5 to 0.8%, that is, 3.1 times. A rational mode of operation of the digger has been determined, which, under these conditions, provides acceptable values for the losses and damage to the tubers