The problem of the rational hole location on the surface of a thin-walled cylindrical gravity tank was studied in order to minimize the stresses around the concentrator. The studies were carried out for three cylindrical tanks with internal diameters of 250, 400 and 500 mm, respectively, with a height of 500 mm and a wall thickness of 20 mm. The diameter of the hole in the tank wall was varied as follows: 6, 10, 14, 18, 20, 23, 25, 30, 32, 36, 40, 45, and 50 mm. The holes were located on the lateral cylindrical surface of the tank, with the following variation of the location heights in relation to the total length of the cylinder element: 4/8, 3/8, 2/8, 1/8, 1/16, 1/32. As a result, it was determined that the increase of the internal diameter of a cylindrical tank increases the equivalent stress around the concentrator. Within some ranges, a change in the diameters of the hole does not actually affect the stress pattern. Using the holes of certain diameters can reduce the stresses around the concentrator.

Composite materials were made by integration of two or more substances, one of them is a supported material like fabric, the other is a matrix material like resin. The outcome of the integration of the two substances produce new material has the attributes differ from the specifications of its constituent materials. This paper presents a comparative study of buckling resistance for cylinders made of a composite material once using a woven cloth as supporting material and the other using knitted cloth. Cylinders have been manufactured, one by woven fabric as supporting material and other by knitting fabric as supporting material, by test the cylinders under the buckling test, we found that the buckle for cylinder producing by knitting fabric is 20% higher than that produced of woven fabric. Comparing the scheme (force-displacement) of the test of two cylinder, it was found that the cylinder producing by knitting fabric has a rapid failure, while the other one has a more displacement.

Introduction. Generation of composite materials with addition of sawdust is considered. The wood component of the composites is treated with water to enhance the surface roughness. This increases the contact area resulting in intensifying the sawdust – polymer fibers interaction. The work objective is to study the possibility of strengthening composites obtained from sawdust.Materials and Methods. Samples are made of composite materials based on the unsaturated polyester resins, reinforced with wood chips. Water treatment was carried out at room temperature for 2, 4, 6 and 8 days. Then the samples were tested for bending and compression.Research Results. As a result of testing the samples, changes in their  mechanical  properties  were  recorded.  It  is  determined how the bending and compression resistance depends on the water treatment time. Graphs that reflect these dependences are constructed.Discussion and Conclusions. After water treatment, the composites reinforced with sawdust show a higher resistance to bending. This is due to the increased roughness of the sawdust surface and, as a consequence, to the extension of the surface area adhesion with the composite base. Besides, the water treatment enhances the specimen resistance under compression. The samples created on the basis of large sawdust come into particular prominence. This is due to the formation of holes on the sawdust surface which also enhances the adhesion between them and the composite polymer base.

The paper is devoted to the research in the field of the effective application of the main working elements of sprinkler machines showing the influence of their basic capabilities on each other. The aim of the study was to develop and improve the performance of irrigation systems for the possibility of irrigation process optimization. As a result, it was found that the ratio between the spray angle and its maximum height at different pressures is equivalent to the second-order parabola equation. The inferred expected dependencies between the radius and the spray angle can be used to determine the degree of spray due to the inclination of the spray tube, which leads to a change in the spray angle when it rotates around its axis and, thus, the degree of spray and the shape of the irrigated area.