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The aim of this study was to develop a new manufacturing process for bimetallic materials by combining laser treatment with traditional casting methods. This process involves laser-treating nickel alloy-grade UNS 6230 plates to create a regular macro-relief on their surface. These treated plates are then placed in a sand mold, and molten non-alloy steel (S235JRG2) is poured into the mold to create bimetallic layered castings. The experimental procedure focuses on optimizing the melt-to-solid phase ratios and pouring temperatures to achieve a uniform microstructure and strong mechanical properties in the bimetals. The produced bimetallic castings are suitable for applications in the oil refining and chemical industries and heavy machinery sector. The quantitative results indicate that the optimized process parameters lead to a high-quality transition zone with minimal defects, characterized by the diffusion of alloying elements from the nickel alloy to the steel. The microstructure, chemical, and phase compositions were evaluated using XRD and SEM with EDS, confirming the formation of a robust metallurgical bond. Key findings include a significant improvement in the hardness and strength of the transition layer, with the optimal pouring temperature being 1600 °C. The resulting bimetallic materials demonstrate an improved performance in demanding industrial environments.

Systems generating strong magnetic fields are widely used in modern fundamental and applied research as well as in the most innovative industrial processes. These devices generate magnetic fields that reach 5–100 T and the conductors are subjected to a huge Lorentz force, so the conductor material must be extremely strong (UTS ≥ 700 MPa) and have a good specific electrical conductivity (IACS ≥ 60%). Since traditional conductors such as copper, aluminum, gold, and silver cannot withstand such loads, microcomposite materials have been developed that are characterized by such high strength and good specific electrical conductivity. This paper reviews the specific electrical conductivity and specific electrical resistance characteristics of conductor and factors affecting them, methods of measuring these electrical characteristics as well as properties of Cu-Nb18% microcomposite conductor. This paper also describes the methodology for measuring the specific electrical conductivity and specific electrical resistance of the Cu-Nb18% microcomposite conductor solid and with welded joint (welded by using butt welding). The comparison of application possibilities of used methodologies and obtained characteristics was carried out. Article in Lithuanian. Cu-Nb 18 % mikrokompozitinio laidininko ir jo virintinių jungčių elektrinio laidumo ir savitosios elektrinės varžos matavimo ypatumai Santrauka Šiuolaikiniuose fundamentiniuose, taikomuosiuose tyrimuose bei inovatyviausiuose industriniuose procesuose yra plačiai taikomi stiprių magnetinių laukų sistemos. Šie įrenginiai generuoja magnetinius laukus, kurie siekia 5–100 T, o laidininkai yra veikiami didžiulės Lorentzo jėgos, todėl laidininkų medžiaga turi būti itin tvirta (UTS ≥ 700 MPa) ir turėti gerą savitąjį elektrinį laidumą (IACS ≥ 60 %). Kadangi tradiciniai laidininkai tokie kaip varis, aliuminis, auksas, sidabras negali atlaikyti tokių apkrovų, buvo sukurtos mikrokompozitinės medžiagos, kurios pasižymi dideliu stipriu ir turi gerą savitąjį elektrinį laidumą. Šiame darbe apžvelgiamos laidininkų savitojo elektrinio laidumo bei savitosios elektrinės varžos charakteristikos, jiems įtaką darantys veiksniai, šių elektrinių charakteristikų matavimo metodikos, Cu-Nb 18 % mikrokompozitinio laidininko savybės. Taip pat šiame darbe yra aprašomos Cu-Nb 18 % mikrokompozitinio laidininko su virintine jungtimi (pagaminta taikant sandūrinį kontaktinį suvirinimą) ir vientiso Cu-Nb 18 % laidininko savitojo elektrinio laidumo ir savitosios elektrinės varžos matavimo metodikos, atliktas metodikų taikymo galimybių ir gautų charakteristikų palyginimas. Reikšminiai žodžiai: elektrinis laidumas, savitoji elektrinė varža, Cu-Nb mikrokompozitiniai laidininkai, virintinės jungtys, matavimai.

Background: The mechanical characteristics of bone are crucial for comprehending its functionality and response to different load conditions, which are essential for advancing medical treatments, implants, and prosthetics. By employing mathematical modeling to analyze the mechanical properties of bone, we can assess stress and deformation under both normal and abnormal conditions. This analysis offers valuable perspectives on potential fracture risks, the effects of diseases, and the effectiveness of various treatments. Therefore, researchers are attempting to find an adequate mathematical description of the mechanical properties of bone. Methods: Experimental stress–stretch external loading curves were obtained through investigations of canine vertebrae. The obtained experimental curves were fitted using the SciPy Python library with a slightly modified logistic function (logistic function plus additional const). Results: The resulting coefficient of determination R2 (R squared) for most curves was near 0.999, indicating that an appropriate fitting function was selected for the description of the experimental stress–stretch curves. Conclusions: The stress–stretch behavior of canine vertebrae can be described using a logistic function modified by adding additional parameters for the most accurate fitting results.

As dogs are considered valuable members of many families, ensuring their health and well-being is essential. This study introduces a numerical nonlinear model that explores the complexities of canine vertebrae, with a specific focus on their experimentally observed mechanical properties. The model underwent rigorous testing, and its results were compared with actual data on the compression of canine lumbar vertebrae. The numerical results and experimental data comparison had a 12% RRMSE. This research enhances our understanding of canine bone health and lays the groundwork for future initiatives aimed at treating and mitigating bone-related diseases in dogs.

This paper describes the development of new metal-processing technologies that enable the control and improvement of the microstructure and properties of metals. This study investigates the impact of one such technology, laser treatment, on the surface of a thin sheet of non-alloy structural steel. This research aims to address a crucial challenge in expanding the industrial applications of thin-sheet steel products by developing a laser processing technology to create structural strengthening ribs, which can significantly influence the overall strength and stiffness of metal components.

In the present experimental study, the transverse oscillating laser beam technique was applied for the post-melting of metal matrix composite coatings, thermally sprayed with nickel-based self-fluxing NiCrCoFeCBSi alloy and 40 wt.% WC, to improve their hardness and wear resistance. The study was conducted using the single module optical fiber laser at 300 W power, >9554 W/cm2 power density, 250–1000 mm/min laser speed, 1 mm and 2 mm transverse oscillation amplitude. Scanning electron microscopy, energy dispersive spectroscopy, Knop hardness measurements, and “Ball-on-disc” dry sliding tests were conducted to study the effect of the processing parameters on the molten pool geometry and microstructure, hardness, and tribology of the processed layers. Oscillating laser processing with an amplitude of 1 mm, 250–750 mm/min laser operating speed, and sample preheating to 400 °C gave a satisfactory result: wide and shallow molten pools of ~200–350 μm in depth, hardness between ~1100 and 1200 HV0.2 and minimum cracks obtained. The coatings obtained with laser beam oscillation and preheating, and ~1150 HV0.2 hardness showed an improvement in the wear resistance and friction coefficient (~0.33) of ~2.9 times and ~20%, respectively, compared with the respective values of the coatings remelted in furnace.

In this paper, the energy characteristics of the charge circuits of a supercapacitor (nonlinear capacitor) and an equivalent linear capacitor from a DC voltage source, which is a lithium-ion battery for such energy storage devices, are analyzed. It is established under what conditions the losses of electricity in the charge circuits of linear and equivalent nonlinear capacitors from the DC voltage source are reduced. The influence of final and initial voltages on similar terminals and capacitance terminals on similar energy losses is analyzed. The regularities of increasing the energy transfer coefficient in the circuits of the aperiodic charge of supercapacitors and equivalent linear capacitors from a DC voltage source (battery) with increasing initial voltages at the capacitor terminals are determined.

This paper presents the results of computer simulations and experimental studies, aiming to increase the mechanical strength of sheet metal parts manufactured from high-quality structural carbon steel by means of local laser processing. The effects of laser processing on the strength of steel sheet plates and their ability to resist bend load after laser treatment were studied. The results of bending experiments and computer simulations of elastoplastic deformation establish that local laser processing with surface melting can be used to increase the mechanical strength of structural elements made from thin sheet steel C22E and to decrease its deflection under similar workload, as an alternative to the application of complex geometric shapes, additional strengthening elements, or heat treatment.

In this work we have evaluated the feasibility of the magnetic field pressing technology for formation of Cu-Nb joints for further pulsed power applications. The electrical and mechanical properties of joints have been investigated. The structure of Cu-Nb conductors joints was investigated using optical and scanning electron microscopy. The mechanical characteristics have been evaluated using tensile tests. It has been determined that the maximum tensile strength of 350 MPa could be achieved, which is 30,4 % of a Cu-Nb wire strength. The applied pressing technology allowed minimizing the defects in the microcomposite structure due to solid-state joining process, however the resultant decrease of conductivity by 10 % influenced an increase of the Joule heating. After a 2 min 200 A current flow the difference of 54,4 °C between the conductor and the joint area was observed. It was concluded that the Cu-Nb joints formed by magnetic field pressing are applicable for pulsed magnet setups where non-destructive joints are required.

A model of the heat exchange process in the heat exchanger of the cardiopulmonary bypass device is proposed which allows for automation of the process of temperature regulation in the cardiopulmonary bypass with an accuracy of ±1 °C during cardiac surgery under controlled cooling and warming of the patient’s heart and brain. The purpose of this research is to create a concept and model of the temperature control circuit using the MSC Easy5 system, the creation of mathematical models of blocks of the temperature control circuit, and the description of the principle of temperature control in the cardiopulmonary bypass circuit. The model of the temperature control loop in the heat exchanger of the heart-lung machine was created using the MSC Easy5 system with a programmable microcontroller. The microcontroller implements a specialized temperature control algorithm in the C language. The model allows the creation of a full-fledged virtual prototype of a temperature control device in a heat exchanger, and helps to conduct virtual tests of the developed device at the design stage. The model identifies control system flaws and influences decisions made before producing an official prototype of the product.

In the present study, pulsed laser post-processing was applied to improve the properties of the thermally sprayed NiCrCoFeCBSi/40 wt.% WC coatings. The powder mix was deposited onto a mild steel substrate by flame spray method and then the as-sprayed coatings were processed by Nd:YAG laser. The peak power density applied was between 4.00 × 106 and 5.71 × 106 W/cm2, and the laser operating speed ranged between 100 and 400 mm/min, providing processing in a melting mode. Scanning electron microscopy, energy dispersive spectroscopy, Knop hardness measurements, and “ball-on-disc” dry friction tests were applied to study the effect of the processing parameters on the geometry of laser pass and microstructure, hardness, and tribology of the processed layers. The results obtained revealed that pulsed laser processing provides a monolithic remelted coating layer with the microstructure of ultrafine, W-rich dendrites in Ni-based matrix, where size and distribution of W-rich dendrites periodically vary across remelted layer depth. The composition of W-rich dendrites can be attributed to a carbide of type (W, Cr, Ni, Fe)C. The cracks sensitivity of coatings was visibly reduced with the reduction of power density applied. The hardness of coatings was between ~1070 and ~1140 HK0.2 and correlated with microstructure size, being dependent on the processing parameters. The friction coefficient and wear rate of coatings during dry sliding were reduced by up to ~30% and up to ~2.4 times, respectively, after laser processing.

Foodborne pathogens are frequently associated with risks and outbreaks of many diseases; therefore, food safety and processing remain a priority to control and minimize these risks. In this work, nisin-loaded magnetic nanoparticles were used and activated by alternating 10 and 125 mT (peak to peak) magnetic fields (AMFs) for biocontrol of bacteria Listeria innocua, a suitable model to study the inactivation of common foodborne pathogen L. monocytogenes. It was shown that L. innocua features high resistance to nisin-based bioactive nanoparticles, however, application of AMFs (15 and 30 min exposure) significantly potentiates the treatment resulting in considerable log reduction of viable cells. The morphological changes and the resulting cellular damage, which was induced by the synergistic treatment, was confirmed using scanning electron microscopy. The thermal effects were also estimated in the study. The results are useful for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections. The proposed methodology is a contactless alternative to the currently established pulsed-electric field-based treatment in food processing.

Modern industrial enterprises require high accuracy and precision feedback systems to fulfil cutting edge requirements of technological processes. As demand for a highly accurate system grows, a thin gap between throughput and quality exists. The conjunction of ultrafast lasers and modern control strategies of mechatronic systems can be taken into account as an effective solution to reach both throughput and tolerances. In the present paper, the dynamic errors of the moving platform of the one degree of freedom stage, based on linear motor and air bearings, have been analyzed. A precision positioning system is investigated as a symmetric system which is based on symmetric linear motor. The goal of the present article is to investigate the controllers of the different architecture and to find the best controller that can ensure a stable and small dynamic error of the displacement of the stage platform at four different constant velocities of the moving platform. The relations between the controller order, velocity and the displacement dynamic error have been investigated. It is determined that higher-order controllers can reduce the dynamic error significantly at low velocities of the moving platforms: 1 and 5 mm/s. On the contrary, the low order controllers of 4th-degree polynomials of the transfer function can also provide small dynamic errors of the displacement of the platform.

This paper presents the experimental results of Cu-Nb wire joining upon applying flash welding technology. The present research is aimed at investigating the structure, electrical and mechanical properties of butt welding joints of Cu-Nb conductors, usable for coils of pulsed magnetic systems. The butt joint structure was found to be free of welding defects. The structure of the butt welded joint provides an insignificant increase in electrical resistance and sufficient ultimate strength and plasticity of the joint. The tensile strength of the welded sample reaches 630 MPa.

A method for the preliminary processing of MRI images of the heart that allows for the elimination of fluctuation and impulse noise from useful signals is proposed. These types of noise are due to the regular geometric structure of the photoelectric elements of the MRI scanner matrix and the structure of the signal transmission channel. The aim of this work is to develop a comprehensive mathematical model for eliminating noise in the signal of an MRI scanner. In this work, mathematical models of linear and median filtering of impulse noise, fluctuation, and geometric noise are implemented. The mathematical models consist of the combined use of linear and median filters for recording MRI images of the heart. In the experiments, real MRI images of the heart from six patients with different diseases were used after noise was added to them. We were able to eliminate the impulse noise, geometric noise, and fluctuation noise in the MRI images by applying our filtering techniques. The filtering technique not only removed the noise, but also increased the contrast of the cancerous volumetric heterogeneous formations in the heart region.

This paper is devoted to investigating numerically, by finite element analysis (FEA), and analytically the influences and effects of laser processing of the surface of thin-plate, low-carbon structural steel. The plate mechanical properties—axial and flexural stiffnesses, force-deflection behavior and cross-section force-strain behavior—are investigated after different laser treatments. An analytical methodology of the estimation of the cross-section area of the laser-processed metal is also proposed in the present article, that can be applied to choosing the reasonable distance between the centers of the laser-processed tracks. The methodology takes into account the width of the laser-processed tracks and the distances between these tracks. The experimental, finite element numerical and analytical analyses showed that the laser treatments of the surface of the steel plate increase the yield point of the laser-processed metal and the axial and flexural stiffnesses of the plate.

The paper presents studies of vibratory treatment effect on the microstructure and hardness of thermally sprayed and re-fused Ni-based coatings. Ni-Cr-B-Si-Fe-C system powder has been deposited on the S235 steel substrate and re-melted with the simultaneous introduction of the horizontal mechanical vibrations of frequency from 50 to 400 Hz and of amplitude from 25 to 185 µm. The microstructure of obtained coatings has been studied along with the microhardness. The grain refinement effect accompanied by the hardness increase has been obtained in vibrated coatings, and frequency from 100 to 200 Hz has been established as the range of the most intensive effect. No visible influence of vibratory treatment on the phase composition has been established.DOI: http://dx.doi.org/10.5755/j01.ms.21.2.6833

In the paper, an opportunity for the development of multichannel transcutaneous raster matrixes for sensors of oxygen on the basis of an electrochemical cell sensor is described. An analysis of the influence of heat sources on the distribution of the temperature pattern of a raster matrix for sensors of oxygen had been carried out, and their optimum configuration had been found. The application of such matrixes will enable one to obtain information about the distribution of the partial pressure of oxygen from the skin cover of the object of research in dynamics, to assess its functional health pattern in a more comprehensive way and to control the effect of possible remedial actions.

High magnetic fields systems is widely used in fundamental and applied research in variuos branches of science and industry. The most famous examples of such magnetic systems are tokomaks, stellators, superconducting magnets, CERN collider, ITER reactor, levitation systems. The key component of magnetic systems is inductor (solenoid). At this moment, the record magnetic fields reaches 100 T. The creation of a strong magnetic field is no longer enough just to improve designs for inductor (solenoid). Traditional electrotechnical materials and conductors can no longer withstand the huge mechanical and thermal loads, therefore, them changes to an entirely new advanced materials, for example Cu-Nb microcomposite conductors. These materials are characterized by a unique structure, excellent mechanical properties and good electrical conductivity. One of the most important and unresolved problems of high magnetic fields systems are reliable non-destructive joints and joining technologies creation. This paper reviews the strong magnetic fields systems design features, Cu-Nb conductors characteristics and structure, microcomposite conductor production specifics, application fields, joining problems and the available joining technologies. Santrauka Stiprių magnetinių laukų sistemos plačiai taikomos fundamentiniams ir taikomiesiems tyrimams įvairiose mokslo šakose ir industrijoje. Tokomakai, stelaratoriai, superlaidūs magnetai, CERN kolaideris, ITER reaktorius, levitacinės sistemos – tai vieni žinomiausių tokių magnetinių sistemų pavyzdžių. Visų magnetinių sistemų svarbiausias komponentas yra induktorius (solenoidas). Rekordinis magnetinis laukas jau siekia 100 T. Stipriam magnetiniam laukui sukurti jau nepakanka vien tik tobulinti solenoidų konstrukciją. Tradicinės elektrotechninės medžiagos ir laidininkai jau negali atlaikyti didžiulių mechaninių ir temperatūrinių apkrovų. Todėl jas keičia visiškai naujos perspektyvios medžiagos, tarp jų svarbią vietą užima Cu-Nb mikrokompozitiniai laidininkai. Šios medžiagos pasižymi unikalia struktūra, puikiomis mechaninėmis savybėmis ir geru elektriniu laidumu. Viena iš svarbių neišspręstų problemų stiprių magnetinių laukų sistemose lieka patikimų neardomųjų jungčių sukūrimas ir jų patikimų sujungimo technologijų paieška, nes dauguma tokių magnetų konstrukcijų turi būti neardomos pradėjus jas eksploatuoti. Tačiau daugiausia jų konstrukcijoje laidininkams sujungti taikomos tik ardomos, deja, praktikoje dideliu patikimumu nepasižyminčios varžtinės arba lituotinės jungtys. Šiame darbe apžvelgti stiprių magnetinių laukų sistemų konstrukciniai ypatumai, perspektyvių Cu-Nb laidininkų struktūros ypatumai ir savybės, kompozitinių laidininkų gamybos specifika, taikymo sritys, sujungimo problemos ir taikytinos sujungimo technologijos. Reikšminiai žodžiai: Cu-Nb laidininkai, mikrokompozitai, virintinės jungtys.

The article examines the plasma sprayed 80Ni-20Al coatings on aluminum-magnesium (Mg ≈ 2.6‒3.6 %) alloy substrate, which before plasma spraying was cleaned using blasting with Al2O3 particles. The wear resistance and corrosion tests of sprayed coating and aluminum-magnesium alloy were performed. The volume loss, average central part of the cross-sectional area of wear track, wear rapidity, wear rate, wear resistance and corrosion current of coating and Al-Mg substrate were evaluated. The wear resistance and corrosion of nickel-aluminum coating and aluminum-magnesium substrate were compared at the work. Furthermore the wear tracks analysis of sprayed coating and substrate surface was carried out. Santrauka Straipsnyje nagrinėjamos plazminiu būdu purkštos 80Ni-20Al dangos ant aliuminio-magnio (Mg ≈ 2,6‒3,6 %) lydinio substrato, kuris prieš padengiant buvo nuvalytas srautinant Al2O3 dalelėmis. Buvo atlikti purkštos dangos, aliuminio-magnio lydinio dilimo ir korozijos tyrimai. Nustatyti dangos ir Al-Mg substrato tūrio nuostoliai, vidutinis išdilusio takelio centrinės dalies skerspjūvio plotas, dilimo sparta, dilimo greitis, atsparumas dilimui ir korozijos srovė. Darbe buvo palygintas nikelio-aliuminio dangos ir aliuminio-magnio substrato atsparumas dilimui ir korozijai. Taip pat buvo atlikta užpurkštos dangos ir substrato dilimo takelių paviršiaus analizė. Reikšminiai žodžiai: plazminis purškimas, nikelio-aliuminio dangos, aliuminio-magnio lydinys, dilimas, elektrocheminė korozija.

Quality analysis of welded and soldered joints of Cu-Nb microcomposite wires has been performed. Quality and mechanical characteristics of joints as ultimate tensile stress limit and elongation at break were measured with an universal testing machine and controlled visually using an optical microscope. Two wires joints were soldered with silver and copper solders and put into steel and copper sleeve respectively. Another two wires joints were soldered with silver solder and welded without any reinforcement. Joints soldered with the silver solder and steel sleeve have demonstrated the best mechanical characteristics: ultimate tensile stress limit of 650 MPa and elongation at break of 0.85 %. Joints soldered with the copper sleeve have no advantages comparing with the soldered butt joint. Ultimate tensile stress limit and elongation at break were in 300 MPa - 350 MPa and in 0.35 % - 0.45 % ranges respectively. Two welded joints had ultimate tensile stress limit of 470 MPa and elongation at break of 0.71 %. In all joints the microstructure of Nb filaments was destroyed and mechanical properties have been specified by mechanical strength of copper and sleeve materials only.http://dx.doi.org/10.5755/j01.ms.17.1.242

The paper presents the study of the influence of mechanical damage on the safe operation of gas transmission pipelines. The main types of pipeline damage with the actual parameters and their influence on the operational parameters are analysed. The damaged fractures of the section of the pipeline Kaunas (Lithuania)–Kaliningrad (Russia) were investigated in the laboratory. The main operational characteristics and the structure of the pipeline’s metal after the period of long-term operation were determined using various research and experimental methods. The influence of the pipeline’s damage was modelled by using the Finite Element Method and the ANSYS code. The predictions of the failure pressure were made, taking into consideration the actual properties of the pipeline’s metal. Techniques including the hardness and microhardness measurement, chemical analysis, the impact strength test, and metallography analysis with an optical microscope, were used in the experimental study.

Nowadays, complex and potentially dangerous structures are usually welded. Manufacturers need to measure welding deformations and residual stresses. Tensometric stations are widely used for control and monitoring of such deformations and stresses. The article discusses a low-cost computer-aided measurement system. Santrauka Sudėtingų ir potencialiai pavojingų pramoninių konstrukcijų gamyboje vienas iš svarbių technologinių procesų tapo suvirinimas. Todėl gamyboje atsirado poreikis matuoti šių konstrukcijų suvirinimo ir liekamąsias deformacijas. Deformacijų kontrolei ir monitoringui plačiai taikomi kontaktiniai ir bekontakčiai būdai. Vienas iš seniai žinomų patikimų matavimų metodų yra tenzomentrinis matavimas naudojant tenzojutiklius ir tenzomatavimo stoteles. Šio darbo tikslas – sukonstruoti nebrangią, kompiuterizuotą tenzometrinių matavimų sistemą ir pritaikyti ją metalinių konstrukcijų suvirinimo deformacijoms matuoti. Reikšminiai žodžiai: tenzojutiklis; tenzometrinis kompiuterinis kompleksas; suvirinimo deformacijos.

A complete study is presented on the response of thermoplastic and thermoplastic composite materials for bearing cages of bogie trains for rail applications to aging conditions in presence of lubricants. Glass Fiber reinforced Polyamaide 66 (GF PA66) is proposed as commercial material already used in the field while Polyether Ether Ketone (PEEK) is proposed as novel polymeric candidate material due to its chemical stability and high mechanical performance. Accelerated aging tests were performed to analyze the response of these materials to external chemical agents under different conditions. Afterwards, a complete set of mechanical and physical tests and characterization procedures were carried out, before and after ageing on suitable samples of the polymers in combination with lubricants, to evaluate the effects of the chemical environment on the mechanical and physical properties of the presented polymers. Results are highly relevant since cages are permanently soaked in lubricant during their operation life. GR PA66 presents better global mechanical properties due to the important glass fiber load (30 %). Nevertheless, the values obtained also show that PEEK remains unalterable under different aging conditions. According to the results it can be suggested that PEEK might be considered as a suitable potential alternative, when necessary, in applications with a high resistance to chemical environment requirements. The lack of published papers reporting behavior of PEEK in the analyzed circumstances highlights the novelty and importance of results obtained in this work.