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

Diamond is currently one of the main reserves for the development of microelectronics. It is with it that tangible progress of this industry is possible, allowing it to reach new technical frontiers, associated primarily with an increase in the speed and power of electronic components. Of the many laser technologies for processing materials in the production of electronic components, the following processes are distinguished: cutting, ablation and welding. For short and ultra-short laser pulse durations, the above processes are applicable under certain conditions, e.g., the thickness and linear size of the element are mainly in the micrometer range. High accuracy of part processing is achieved by using the size of the laser spot on the surface > 0.5 μm and a power density of about 109 W/cm2. This can be realized by increasing the uniformity of the laser beam, controlling the pulse shape, and selecting the wavelength of the laser radiation. Laser ablation, especially on metal structures, is implemented using nano-, pico- and femptosecond pulses. If the laser power density values are much higher than the threshold for ablation, treatment occurs at 120 fs < tp <150 fs using wavelengths of 800 and 1064 nm. The features of laser ablation in metals, semiconductors, and dielectrics are to reduce the threshold power flux density if the pulse duration is reduced from nano- to femtoseconds. The main promising areas of predominant application of diamond and diamond-containing materials in the production of components of electronic equipment are presented.

Plasma-based ion implantation (PBII) is a surface modification technique that applies a negative high-voltage pulse to a sample immersed in plasma. PBII is suitable for samples with complex geometries, as its ion sheath conforms to the sample’s shape, ensuring uniform ion implantation. Due to its precise controllability, PBII is widely used industrially for surface modification and has promising applications for sterilization. We previously used PBII with oxygen gas to successfully sterilize heat-resistant spore. Here, we evaluated the use of PBII with HHO as the process gas for sterilization. Sterilization exceeding 7D was achieved at 10 min and 3 Pa. The enhancement of the sterilization efficacy was attributed to the synergistic effect of plasma and thermal energy, which emerged as a consequence of a temperature increase exceeding 100°C due to adjustments in pulse width and delay time. These results indicate the possibility for temperature control in PBII technology, which has potential application in sterilization processes.

An coupled analytic-numerical model for calculation of distortions arising by welding fabrication is introduced. Target of the analytical model is the calculation of the inherent strains after the local thermal-mechanical influence of the welding or thermal straightening process. Following the fabrication processing chart the strains are loaded on an elastic FE-model of the structure and the residual stresses and distortions of the whole structure are calculated. The consideration of welding and thermal straightening scenarios, inclusively the assembling stages, is done by taking into consideration the intermediate variation of the strain state in the FE-model of the structure at every processing step. The important physical relations are demonstrated. The model is intended to be used for solving industrial tasks, i.e. intending acceptable precision and calculation time as well as low simulation costs.

Austenitic stainless steels are widely used in various industries, including petrochemicals, food processing, and textiles, due to their excellent corrosion resistance, acceptable mechanical properties, and cost-effectiveness. Additionally, their good weldability makes laser welding a popular choice for manufacturing various designs. However, achieving optimal weld quality in laser welding requires precise and controlled adjustment of several key parameters. In this study, the effects of two fundamental process parameters—laser power and welding speed—on the mechanical properties of laser-welded AISI 316 stainless steel structures were investigated. For this purpose, a 2-factor, 3-level full factorial experimental design was implemented. The welded structures were subjected to tensile testing, and their microstructures were analysed.

The metal materials are subject to severe temperature variation during the application of the welding process. The heat input and thermal shock during arc welding cause change of the base material properties in the heat affected zone. Temperature measurements and destructive tests of sample pieces, subjected to different process parameters and conditions, enable identification of minimum and maximum cooling rates, at which the material properties remain in pre-defined limits. Temperature measurements on the surface of the material in proximity to the weld seam enables cooling rate monitoring and material properties evaluation at manufacturing or site installation conditions, when the products could not be subjected to destructive tests. The requirements to the surface temperature measurement during welding and the characteristics of the different measuring devices were investigated for fitness to the purpose of cooling rate calculations, material properties evaluation, as well as for calibration of welding process simulations in volumes in close proximity to the arc welding seams.

In this article,tensile creep elongation of PE plastic films with two configurations of open holes stressed at the incremental temperatures of 23,30,37,43,51,58 degrees and a constant dead weight of 50 kg will be analyzed. The aim of the article is to analyze influence of the two configurations of open holes on the relative elongation. The test was conducted with the same blend, under the same test conditions. The test was conducted entirely according to the conditions established in the ASTM D6992 standard.

An coupled analytic-numerical model for calculation of distortions arising by welding fabrication is introduced. Target of the analytical model is the calculation of the inherent strains after the local thermal-mechanical influence of the welding or thermal straightening process. Following the fabrication processing chart the strains are loaded on an elastic FE-model of the structure and the residual stresses and distortions of the whole structure are calculated. The consideration of welding and thermal straightening scenarios, inclusively the assembling stages, is done by taking into consideration the intermediate variation of the strain state in the FE-model of the structure at every processing step. The important physical relations are demonstrated. The model is intended to be used for solving industrial tasks, i.e. intending acceptable precision and calculation time as well as low simulation costs.

In many cases, the importance of electromagnetic fields or the so-called “electromagnetic smog” on human health, living organisms, and the environment is ignored or at least minimized. The electromagnetic field (EMF) is a combination of invisible electric and magnetic fields with charge that occur in nature. Today, the impact of electromagnetic fields on the environment is increasing from human activities with the development and application of telecommunication technologies. Measurement, continuous monitoring, database creation, and evaluation of electromagnetic field parameters in urban environments are important aspects of optimizing EMF levels to achieve a healthy living environment. The paper presents an analysis and evaluation of electromagnetic radiation measurements from base stations of mobile operators, at one site, in a lightly urbanized urban environment over a certain time interval. Initial measurements showed exceeding the levels of electromagnetic emissions according to national legislation. During the repeated measurements, it was found that mobile operators, after correcting the radiation from base station antennas, have brought the radiation levels within the permissible limits. This underscores the necessity of ongoing monitoring.

The aim of this paper is the calculation of the PLEM (Pipeline End Manifold) System of the 18″ dia. subsea pipeline, according to the International Codes and Standards. A Geotechnical survey was carried out to define soil – structure interaction, effect of scour, soil stratigraphy and susceptibility to liquefaction. Then were defined the acting forces on PLEM, pipeline and submarine hoses taking in consideration the total buoyancy as well. The calculation was carried out for filled pipeline (in service), as well as for empty pipeline. The ground conditions along the sealines and at the location of the PLEM have been investigated by a dedicated additional site investigation, consisting of 12 no. vibrocore samplings and the related laboratory testing. The stability of PLEM was checked for several load combination. This calculation it was very important for environmental reason and shows that the structure meet the requirements of the project.

This paper discusses contact interaction under mechanical stress and how vibrations change the physical properties of conductor materials, which affects their ability to provide reliable contact. It also analyzes the causes of contact failures, which allows us to better understand the mechanisms that lead to problems in the operation of electrical connectors. These factors can lead to serious consequences, including breakage and reduced reliability of connectors, and also considers the possibilities of improving the characteristics of electrical contacts at the stage of their creation, using various technologies for applying and creating an approximately ideal molecular structure of the contact surface of detachable electrical connectors, with an increase in the surface layer of the contact and a decrease in the coefficient of friction.

In the article, experimental results according to ASTM D6992 standard test method for accelerated tensile creep of plastic films were investigated and analyzed. A regression model was created based on the obtained results. Real and theoretical data were compared. In order to determine deviations of the model and what is the reliability of the theoretical data.

Paper deals with determining the possible savings of electrical energy in a passenger elevator. After carrying out calculations with a set number of floors of an administrative building and number of passengers according to a proven and widely used methodology in Bulgaria, an appropriate three-phase squirrel-cage induction motor has been selected to drive the considered elevator system. Calculations have been also carried out on the possible recovery, i.e. returning electrical energy back to the supply power grid when the driving rotating electrical machine is switched to generator mode. Variants with different number of passengers and movement of the cabin in upward and downward directions were theoretically studied. The active power, time to work in recovery mode and the active energy returned to the power grid are defined for each specific case. Calculations of possible electrical energy return in generator mode would be of interest to specialists dealing with these technical facilities.