International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This work examines the relationship between two of the most important mechanical parameters: shear and tensile strength in 3D printed polymer test specimens using Fused Deposition Modeling. Different types of materials were used, including those that are mechanically strong, easy to print, flexible, and heat-resistant, to determine their behavior. The study was conducted by testing test specimens printed with the same characteristics of percentage filling and pattern, layer height, and printing direction. The ratio between the shear strength and tensile strength of seven polymer materials with 30 % infill in percent was calculated. The values were compared with those of metals and polymers with 100 % density, and an estimate of the coefficient between the two parameters was made.

In the development of new composite structural elements based on sedimentary rocks (clays) as inorganic binders and foam composite materials, their physical characteristics are presented for the construction of recipe compositions and the determination of their complex new properties. The role of the components of the compositions, together with organic reinforcing fiber materials such as straw, rice husks and others, basic parameters of the technological regime and other factors for ensuring adequate workability of the prepared composite compositions for obtaining building coatings and elements – bricks and panels for building ecological houses – is considered. The determination of the necessary technological characteristics of the composite mixtures ensures their effectiveness.

The fluids that are present in the underground reservoirs of oil and gas, both in the initial conditions and in the exploitation conditions of the reservoir, experience different phase behavior. All these are accompanied by different physico-chemical parameters, the determination of which plays an important role in the hydrodynamic study of the well or the reservoir as a whole. The fluids released from the formation change over time due to the change in the phase state of the fluids, their material and energy balance. In this study, based on the field data obtained during the exploitation of the oil and gas bearing bed, the physico-chemical parameters of the gas were determined based on the correlations derived from the various experimental studies carried out in the world.

The technological characteristics of suspensions used in the development of new thermal insulation composite structural elements based on foam materials and inorganic binders (Portland cement) are investigated. The role of the components of the compositions, the parameters of the technological regime and other factors in ensuring adequate workability of the prepared cementitious solutions is considered. Determination of the necessary technological characteristics of composite mixtures ensures their effective distribution in the formwork moulds when forming the specimens, cost-effective performance at production stage and obtaining products with the planned
functional properties. The existing opportunities for potential application in modern construction of the developed composite elements are analyzed.

The combined application in a foundry practice of 3D-printing, computer optimization through a virtual casting and modern visualization, by color scales and comparisons allows to be obtained details free of defects from the very first casting. One specific example for a fast optimized casting of a crankcase of aluminum alloy for a turbocharger is shown. The geometry of the detail is of high complexity, developed internal cavities and various wall thicknesses. With the use of three advanced software products, the time to reach the above goal is shortened by about two months and the minimum density in a critical point is increased almost 3 times

Soil water retention and soil compaction are very important factors in the plant production and environment protection. The field investigations of the variation of soil moisture and soil density of Luvisol loamy sand in arable layer and in hard pen during sugar beet growing season in conventional tillage with implementation of mineral and organic fertilization were realised. In the growing season the soil moisture extremely fluctuates in the range from 4 to 18%. At the same time, it causes fluctuations of soil density, which totally decreases in time. Starting from June one can observe that the natural changes of the soil moisture cause contrary changes of soil density. Mostly, the soil moisture and soil density variation during growing season are similar in ruts and at the field besides the ruts. Generally, the organic fertilization increases the soil retention to about 4 % in arable layer and profitable enhance the loosened action of water.

New multicomponent glasses in the system WO3-La2O3-B2O3-Nb2O5 doped with Eu3+, as a transparent active media for optical application were obtained. Physical parameters as density, molar volume, oxygen molar volume and oxygen packing density were determined. The thermal behavior of the obtained glasses was examined by differential thermal analysis (DTA). It was established that glass crystallization temperature is about 750oC. Microstructural characterization was made by Raman and UV-VIS spectroscopies. Based on the obtained spectral data short-range order and connectivity in glass network were determined. High photoluminescence emissions due to the 4f transitions 5D0→7Fj (j=0-4) of Eu3+ ions were observed. Colorless bulk tungstate glass, containing Nb2O5 with high transparency and high refractive index were prepared.

Surface saturation with boron of Fe-C-Cu construction powder materials aims to improve the surface hardness of the articles and hence improve wear, contact strength and other mechanical properties. This study investigates the influence of single-component diffusion enrichment modes with boron of semi-permeable powder metallurgical samples from the Fe-C-Cu system. The powder samples on the basis of iron powders NC 100.24 to which 0,3 ÷ 2,5% Cu and 0,4% carbon were added were subjected to the study. Diffusion saturation with boron was carried out in semi-permeable saturation media with a composition of 84% Na2B4O7 + 12% SiC + 4% K2Cr2O7 at temperatures 850 ÷ 950 ° C for 2 ÷ 4 hours. Graphical dependencies are presented for the variation of the diffusion slit thickness in the longitudinal section of the test samples depending on their density, duration and saturation temperature. The experimental results obtained are compared with those obtained by combining pure iron samples with the same technological parameters.

The results of experimental studies of the compression process during the sintering under high pressure conditions of wurtzite boron nitride and diamond powders mixture of submicron sizes obtained by different technologies are given. It is determined that the compaction level at obtaining compositions depends on the dispersion and nature of the diamond component. Interaction of wurtzite boron nitride with diamond proceeds more intensively with diamonds of dynamic synthesis, but it is accompanied by their partial graphitization.

The potential of using the ultrafine dispersion powder material obtained by the ECA pressing from a copper powder have considered for the production of fast-acting fuse links. The dependences of the density and microhardness along the length of the sample under different deformation conditions obtained. A deformation zone of constant density is determined and recommended for using in the production of fuse links. The dependence of the electrical resistance along the sample cross-section and across the deformation axis has determined. The fuse links calculation procedure has proposed.

The theoretical and experimental study of stress-strain state and density distribution into the billet at equal-channel angular pressing has been conducted. It has shown clearly that deformation zone takes a substantial volume with dramatic non-uniformity of stress- strain state after the first pass of equal-channel angular pressing at the backpressure of 90 MPa. The presence of turbulence zone that ensures structure fragmentation of material has established by microhardness indentation. A possibility of production of high-density billets after the second pass at the backpressure of 150 MPa with high mechanical properties and more uniform stress-strain state, free of loosening and cracks has presented.

In the present study the influence of the monitored type iron powder, and the process of sintering in the presence of a liquid phase on the tensile strength of the powder metallurgical samples of the system Fe-C-Cu . Research samples are subjected made of three types of iron powders – ASC 100.29, SC 100.26 and NC 100.24. Thereto is added of 0,2 to 0,8% carbon and 2,5% copper. After sintering the measured density of the samples in the range of 6,20÷7,00g/cm³. Are presented graphics, amending the tensile strength of the samples depending on their density and the concentration of copper and carbon in the iron matrix.