• ## THEORY OF CALCULATION FOR STRENGTH TRAY PLANTS FOR THE PRODUCTION OF HYDROPONIC GREEN FODDER

Production of hydroponic green fodder is an important task of agriculture, which in developed countries is given enough attention. Currently, the world’s developed a considerable number of various designs installations for the production of hydroponic products, but the main working body of these installations are trays in which the cultivation of hydroponic green fodder, as one of the most simple, but fairly effective devices for seeding, cultivation and the ready products. Due to the fact that each of the trays used for these purposes is a resilient structure which is under the influence of considerable forces and bending moments, to design it requires fairly accurate preliminary and final strength calculations. The aim of this study is to develop guidelines on the calculation theory of plant trays strength for the production of hydroponic green fodder. The study used modeling techniques, higher mathematics, mechanics of materials and structures, in particular the theory of elasticity of plates and shells, as well as the methods of calculation and programming on a PC.

The study built a mechanical model and the design of the tray scheme, defined analytical expressions to change the maximum and calculated moments in his dangerous sections and constructed diagrams of bending and torque. Further graphs of changes in the safety margin of the tray frame, depending on the area of seed tube parameters and from which it is made. These charts should be used for the calculation and control of the results. A new theory can be used in calculating the strength of similar containers, which are used in the mechanization of agricultural production

• ## THEORETICAL PREMISES FOR ENHANCEMENT OF EFFICIENCY IN THE USE OF REVERSIBLE PLOUGHS

Theoretical analysis has been undertaken to determine the effect of the plough’s structural layout on the total length of the tractor- implement unit’s turning path. Basing on the results of the analysis, the utility of employing a reversible plough instead of a conventional one has been assessed. Eventually, it has been found that, when ploughing a 68.2 m wide land with an area of 8.2 hectares, the total length of the path of travel on the headlands is 1980 m for the reversible plough unit and 2035 m for the conventional plough unit, which is an increase by 2.7%. At an average manoeuvring speed of 1.75 m/s (6.3 km/h), the total amount of time spent for turning by a unit with conventional ploughing tools will be greater by mere 0.5 min. If the ploughed land is magnified by almost 1.5 times (12.0 hectares instead of 8.2), the width of the field will reach 100 m. In this case, the ploughing unit with a conventional plough will travel an 850 m longer path on the headlands. At the above-mentioned average headland manoeuvring speed of 1.75 m/s the increase of time spent by this type of tilling unit for turning will amount to just 8 min. The only advantage of the reversible plough over the conventional one is the opportunity to avoid the appearance of crown ridges and dead furrows when tilling the field. Meanwhile, it is to be noted that with a sufficient qualification of the machine operator the said advantage of the newer tilling implements can be levelled down. Considering the equal productivity of the compared tilling units, a negligible difference between their rates of non-productive expenditure of working time as well as taking into account the infrequent performance of ploughing, i.e. once in several years, in view of the considerably (several times) higher cost of a reversible plough, the acquisition of the latter presents an economically inadvisable option.

• ## THEORY OF ASYMMETRIC IMPACT INTERACTION BETWEEN VIBRATING DIGGING TOOL AND BODY OF SUGAR BEET ROOT

One of the most important characteristics of the high performance operation of a state-of-the-art sugar beet harvester is the provision of the conditions that make impossible the damaging of sugar beet roots immediately during their digging out of the ground as well as their loss in the form of broken off tails, which either remain in the ground or get left on the field surface. It is quite obvious that the highest probability of damaging sugar beet roots exists at the instant of their impact interaction with the digging tools, because then the bodies of the roots are tight in the ground. This is to the greatest extent applicable to vibrating digging tools, which can be found on the majority of up-to-date sugar beet harvesters manufactured worldwide, when they operate under the conditions of dryer and harder soil.

Therefore, we have carried out theoretical research into the process of impact interaction between the body of a sugar beet root fixed tight in the ground and the vibrating digging tool, the results of which provide sufficient grounds for determining the optimal kinematic and design parameters of the vibrating digging tool stipulated by the requirement to eliminate the damage of roots during their digging out of the ground. At first, we developed an equivalent schematic model of the force interaction between a sugar beet root fixed tight in the ground, which was approximated by a regular cone, and two shares of the vibrating digging tool simultaneously oscillating in the vertical longitudinal plane at the preset amplitude and frequency and moving onward. Under these conditions, the body of the sugar beet root made contact at one point with only one share of the digging tool, i.e. they came in asymmetric contact and their impact interaction took place. We introduced the axes of a three-dimensional Cartesian coordinate system and found the analytical expressions for all forces applied to the sugar beet root at the specified point and also for the force of its bond with the soil. Also, we took into account that an impact momentum was applied at the point of contact at the moment of impact, its value was found analytically, and further we found its projections on the coordinate axes. Then we applied the theorem of variation of the momentum during impact and, following the substitution into it of all found values and transformations, we obtained a new system of equations that characterised the impact interaction process under consideration.
The obtained system of equations was solved using Cramer’s rule on a PC with the software programme developed for this purpose. As a result, we found the digging share vibration frequency and soil running depth ranges, within which the requirement to eliminate the damage of tail parts of root bodies fixed rather tight in the ground was met. Applying the devised theory it becomes possible to determine the kinematic and design parameters of the vibrating digging tool that ensure observance of the requirement to eliminate the breakage of root bodies during their lifting from the ground, within a wide range of the soil’s mechanical and physical characteristics.