Magnetoplasma compressor (MPC), a type of plasma accelerators, is used for treatment and alloying of steel samples: steel 100Cr6, steel 16MnCr5 and steel 42CrMo4. The high-speed plasma flow formed ...within the MPC, from helium with 5% of hydrogen as working gas, is directed to the surface of the samples. The energy flux density of the plasma flow in the plasma-sample interaction area is 9 Jcm2. Plasma melts the near-surface layer and during the rapid cooling process, a thin layer with structure different from initial is created. Changes in the physical composition of the substrate are monitored depending on the number of plasma treatments. After treatment with a plasma produced within MPC, a significant improvement of hardness has been achieved.
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•Steel surfaces are treated with plasma formed within a special type of plasma accelerator: magnetoplasma compressor (MPC).•Every plasma shot deposit 9 J/cm2 of energy to the surface of the treated material.•Hardness of steel 100Cr6, steel 16MnCr5 and steel 42CrMo4 is improved after treatment with plasma produced in MPC.•Smoothing of the peripheral region of the surface microrelief occurs after a sufficient number of the plasma treatments.•There is a phase change from a singly α-Fe to combination of α and γ-Fe after steel 100Cr6 has been treated with plasma pulses.
Additive manufacturing technologies have developed rapidly in recent decades, pushing the limits of known manufacturing processes. The need to study the properties of the different materials used for ...these processes comprehensively and in detail has become a primary goal in order to get the best out of the manufacturing itself. The widely used thermoplastic polymer material acrylonitrile butadiene styrene (ABS) was selected in the form of both filaments and ABS-like resins to investigate and compare the mechanical properties through a series of different tests. ABS-like resin material is commercially available, but it is not a sufficiently mechanically studied form of the material, which leads to the rather limited literature. Considering that ABS resin is a declared material that behaves like the ABS filament but in a different form, the objective of this study was to compare these two commercially available materials printed with three different 3D printers, namely Fused Deposition Modelling (FDM), Stereolithography (SLA) and Digital Light Processing (DLP). A total of 45 test specimens with geometries and test protocols conforming to the relevant standards were subjected to a series of tensile, three-point bending and compression tests to determine their mechanical properties. Characterization also included evaluation of morphology with 2D and 3D microscopy, dimensional accuracy of 3D scans, and Shore A hardness of each material and 3D printing process. Tensile testing results have shown that FDM toughness is 40% of the value for DLP. FDM elongation at break is 37% of DLP, while ultimate tensile stress for SLA is 27% higher than FDM value. Elastic modulus for FDM and SLA coincide. Flexure testing results indicate that value of DLP flexural modulus is 54% of the FDM value. SLA strain value is 59% of FDM, and DLP ultimate flexure stress is 77% of the value for FDM. Compression test results imply that FDM specimens absorb at least twice as much energy as vat polymerized specimens. Strain at break for SLA is 72% and strain at ultimate stress is 60% of FDM values. FDM yield stress is 32% higher than DLP value. SLA ultimate compressive stress is half of FDM, while value for DLP compressive modulus is 69% of the FDM value. The results obtained are beneficial and give a more comprehensive picture of the behavior of the ABS polymers used in different forms and different AM processes.
Industry 4.0 in Serbia: State of development Majstorović, Vidosav; Mitrović, Radivoje; Mišković, Žarko
Serbian journal of management,
01/2022, Letnik:
17, Številka:
1
Journal Article
Odprti dostop
A new model of automation of technological systems, based on the Internet, was defined as the concept of Industry 4.0, Germany in 2011. It represents an advanced model of connecting machines and ...computers (cyber-physical systems - CPS), their networking (cloud computing and Internet of Things (IoT)) with the widespread use of advanced artificial intelligence (AI) in this concept. This concept is a model of smart manufacturing (SM), and today we are talking about: smart vehicles, smart highways, smart grids, smart cities, smart services, etc ... - in short, intelligent "everything and anything" (smart everything). The most important directions for Serbia in the application of Industry 4.0 include: industrial policy for Industry 4.0, education for Industry 4.0 (higher / secondary education), research for Industry 4.0, and especially applied research and readiness of SMEs for Industry 4.0, as well as the application of this model in practice. This paper presents the development and application of the Industry 4.0 model in Serbia, through the activities of the Faculty of Mechanical Engineering in Belgrade, from 2015 until today, with special reference to the application of Industry 4.0 in mining.
One of the most important factors influencing ball bearings service life is
its internal radial clearance. However, this parameter is also very complex
because it depends on applied radial load and ...ball bearings dimensions,
surface finish and manufacturing materials. Thermal condition of ball
bearings also significantly affects internal radial clearance. Despite many
researches performed in order to find out relevant facts about different
aspects of ball bearings thermal behaviour, only few of them are dealing with
the real working conditions, where high concentration of solid contaminant
particles is present. That?s why the main goal of research presented in this
paper was to establish statistically significant correlation between ball
bearings temperatures, their working time and concentration of contaminant
particles in their grease. Because of especially difficult working
conditions, the typical conveyor idlers bearings were selected as
representative test samples and appropriate solid particles from open pit
coal mines were used as artificial contaminants. Applied experimental
methodology included thermographic inspection, as well as usage of custom
designed test rig for ball bearings service life testing. Finally, by
obtained experimental data processing in advanced software, statistically
significant mathematical correlation between mentioned bearings
characteristics was determined and applied in commonly used internal radial
clearance equation. That is the most important contribution of performed
research - the new equation and methodology for ball bearings internal
clearance determination which could be used for eventual improvement of
existing bearings service life equations.
Reliable and resilient constructions are basic for ensuring the safety of various structures. The superalloys are used as constructive materials due to their superb mechanical properties and ...endurance. However, even these materials can have certain areas where the stress concentration is higher than expected, such as drilling holes, which are common in various structures that need additional enhancement. Surface laser modifications of the areas surrounding the holes drilled in Nimonic 263 sheets are done by pulsed picosecond and nanosecond Nd:YAG laser irradiations with pulse durations of 170 ps and ≤8 ns, respectively. Following the laser surface treatment, the effectiveness of the enhancement was analyzed by the microhardness test and the deformation test. The results show that the deformation and stress values are decreased by 25−40 percent, showing the improvement in the resilience to deformation. The Vickers microhardness test results indicate an improvement in the Nimonic 263 microhardness. The dimensions of the microcracks are higher for the untreated material in comparison to the laser-treated material.
Purpose
This paper aims to present the methodology to determine Archard’s wear coefficient. By applying this coefficient into the numerical simulation of wear, it is possible to predict wear without ...long lasting and usually expensive experiments.
Design/methodology/approach
To determine necessary particles of Archard’s equation and calculate wear coefficient K, an experimental investigation is proposed. Afterwards, the wear simulation is executed in FEM software ANSYS 18.1. Analytical method is offered to determine worn volume for cylinder-in-cylinder contact, based on “inclination” of inner cylinder.
Findings
Comparing the value of Archard’s coefficient obtained by this experimental investigation with the values from the literature for the similar materials, high correlation is noted. Furthermore, numerically calculated contact pressure is confirmed with analytical method. Trend of pressure decrease due to wearing process, as well as due to increase of contact surface is observed.
Practical implications
Since the prediction of the wear is closely related to the life cycle assessment of bearings, and the machines in general, it has significant practical importance for designers.
Originality/value
Determination of Archard’s coefficient is usually performed by conventional pin-on-disk tribometers. This methodology offers a different approach for the determination of Archard’s wear coefficient for cylinder-in-cylinder contact, which is convenient for shaft-sliding bearing contact.
Locking Compression Plates (LCP) have found application in the orthopaedic healing process in modern medicine. Their design is specifically modified depending on the bone and the loading the specific ...bone is subjected to. Dimensions of LCP, as well as mechanical characteristics, provide greater structural resistance than the bone itself; in practice, however, continuous application and cyclic loading can lead to fails and fractures. Defining of the testing approaches and procedures used for the evaluation of the stress and location of geometrical areas with potential risk of the stress concentration represent the aim of this investigation. Results obtained in this paper show that combined use of modern experimental methods (DIC) and numerical simulations on the modified and simplified LCP geometry, can be used to locate stress and strain fields, as well as areas with stress concentration that can result in the appearance of cracks during cyclic loading.
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