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New protective coatings based on pyrophyllite and zirconium silicate
No full textThe paper presents the results of the synthesis and characterization of refractory coatings based
on pyrophyllite (80%) and zirconium silicate (20%) with a binder based on epoxy resin intended
for the protection of metal and non-metal constructions and parts of equipment in industry.
Samples of refractory fillers were subjected to micronizing grinding to the filler grain size:
pyrophyllite 20μm and zirconium silicate 15μm. This achieved a good alignment of the filler
particles with each other. XRD, SEM, and optical microscopy methods were used to characterize
the obtained fillers. The optimal composition of protective coatings and the procedures for their
production were determined by testing. The ultrasonic vibration method with a stationary sample
according to the ASTM G32 standard was used to characterize the obtained coatings. The aim of
the test was to determine the quality of the coating and the possibility of application for the
protection of metal surfaces in conditions of wear, corrosion, cavitation, and elevated
temperatures. The quality of the coating was evaluated based on the value of the cavitation speed
and the analysis of the formation and development of damage to the surface of the samples under
the effect of cavitation. Based on the measurement of mass loss during the test under the effect of
cavitation, the cavitation speed was determined (V = 0.31 mg/min), and the morphology of the
damaged surfaces was analyzed by recording the surface of the coating on a scanning electron
microscope. It was established that mass losses and the formation of pits on the surface of the
coating were small and that the surface damage was 16.5%, which shows that the tested coating
samples have satisfactory cavitation resistance. The tested coatings based on pyrophyllite and
zirconium silicate can be applied to protect metallic surfaces in conditions where moderate
cavitation effects are expected
Implementation of a cutting forces model through virtual simulation of machining process
No full textThis paper presents the development of a methodology for monitoring the part machining process on CNC machine tools
using a virtual machine model in the MATLAB/Simulink environment. The focus is on monitoring the components of cutting
forces that occur during the milling process. A vertical milling machine was used for model validation. By integrating
the existing cutting force model and the virtual machine model in MATLAB/Simulink, the visualization of real-time cutting
force values, which depend on the change of the current engagement map along the programmed toolpath, is enabled. The
development of the presented simulation environment forms the basis for the implementation of new functions in G-code,
contributing to the stability and optimization of the machining process
Nova Uredba o mašinama (EU) 2023/1230
No full textRad analizira evoluciju regulative EU koja se odnosi na bezbednost mašina, od prvih direktiva do najnovije Uredbe (EU) 2023/1230, koja zamenjuje trenutno aktuelnu Direktivu 2006/42/EC. Opisani su ključni zahtevi za proizvođače mašina, promene u zakonodavstvu, te izazovi koje donosi primena nove Uredbe. Cilj rada je da ukratko prikaže uticaj novih regulativa na proces konstruisanja mašina namenjenih EU tržištu, kao i na pripremne aktivnosti koje proizvođači moraju preduzeti pre početka zvanične primene Uredbe 2027. godine
Green Ship Solutions for Sheltered Maritime Waters and Inland Waterways in the Western Balkans
No full textSince its introduction, the Green Deal and its incentives have encouraged a shift from road to waterborne transport to reduce greenhouse gas emissions and traffic congestion. In response, numerous initiatives have been undertaken to design ships and boats whilst incorporating green technologies. This study assesses existing and proposes new waterborne ship concepts that employ green and innovative technical solutions for the navigation in sheltered maritime waters and inland waterways of the Western Balkans. Despite their apparent differences, inland waterways, such as the Danube and Sava rivers in Serbia, and sheltered maritime waters and lakes, such as the Bay of Kotor and the Lake Skadar in Montenegro, share several characteristics: a limited range of navigation, reduced speeds to minimize ship-induced large disruptive waves, and the absence of significant weather-induced waves. These conditions make ideal testing ground for electric and hybrid vessel solutions. Despite challenges such as regulatory barriers, safety concerns, and the limitations of still-maturing technologies, this work demonstrates that some solutions are viable for such environments. Achieving this requires defining precise navigation conditions and ship requirements, while adhering to established principles of naval architecture
Impact properties of FDM-grade PLA material relative to infill density
No full textOne interesting feature of Additive Manufacturing (AM) is the ability to manipulate the internal structure of fabricated objects. In FDM (Fused Deposition Modeling) technology, the heated nozzle deposits the melted thermoplastic material onto a build platform. Namely, both the filling pattern and density can be controlled here. Depending on the slicer software, the filling pattern can be arranged in triangles, hexagons, cross lines, etc. The density can vary between 10-100%, with an increment of 10%. This research paper will focus on the influence of infill density on the impact properties of FDM-grade PLA material, i.e., how properties degrade with lower infill percentages. The full infill density spectrum (abovementioned) will be presented here. The authors’ previous research findings show the benefits of low layer thicknesses, in terms of result repeatability and impact strength values. Thus, the employed layer thickness here is 0.1 mm, the lowest resolution for most FDM machines. The impact tests are performed on an Instron CEAST 9050 instrumented Charpy test rig, mounted with a 5J hammer (see Fig. 1). The specimens are prepared according to the ISO 179-1:2010 standard, with seven specimens per condition
Classification of offshore oil and gas plants
No full textOil and gas plants can be classified into onshore and offshore plants, colloquially called oil and gas platforms, or simply oil platforms. Oil rigs represent an enormous feat of engineering developed from over 150 years of industrial expertise. This paper shows the classification of oil and gas
platforms according to their structures and purposes, and describes the types of oil platforms, their structure, advantages and disadvantages
DETERMINATION OF FRACTURE MECHANICS PARAMETERS ON PIPE RING NOTCH TENSILE (PRNT) SPECIMENS
No full textDetermining the parameters of fracture mechanics is a key segment in assessment and enhancement of the safety and longevity of materials and structures, especially when they are exposed to extreme load conditions in the presence of damage. In this work, one group of such structures is considered - thin-walled pipelines, which are used in practically all process
industry branches. Since the standard procedures prescribed by ASTM and ISO standards are not the most relevant if one of the criteria is not met, which is the testing of materials in plane strain state, it is necessary to develop a complete procedure for testing fracture mechanics parameters for thin-walled pipelines. This paper will present the results of experimental and numerical analysis of fracture mechanics parameters determined by a non-standard procedure for PRNT (Pipe Ring Notched Tensile) ring-shaped specimens, introduced in [1] through analysis of 3D printed polymer rings. The specimens are examined using a specially designed tool on a universal machine for testing the mechanical characteristics of materials with a working capacity of 100 kN and a sensitivity of 1 N. The parameters related to the displacement of points on the samples were measured and calculated based on the results obtained by the digital image correlation method (DIC). In this work, the main topic is determination of the values of previously mentioned fracture mechanics parameters; since the specimens are not standard, finite element software package Simulia Abaqus is applied for determination of these values. On the tested geometries, the ratio of the width of the sample to the initial length of the sharp stress concentrator (a sharp notch or a pre-crack) was varied (a0/W = 0.4 – 0.6). Also, a wider range of this ratio is used for one of the geometries, in order to extend the application range. Since J-integral
values are typically calculated as sum of the elastic and plastic part, the main parameters which are needed are: stress intensity factor KI, plastic geometry factor η and crack propagation correction factor γ. Generally, it can be said that the obtained parameter values showed almost linear dependence on the ratio a0/W and a slight difference in the values due to varying dimensions such as width, wall thickness and cross-section of the model. This consistency indicates a good potential of the procedure and the possibility of practical implementation on the thin-walled pipelines
Artificial Intelligence Methods On Sustainable Path In The Function of Energy Efficiency Increase
No full textArtificial intelligence (AI) methods have emerged as pivotal tools in the quest to
enhance energy efficiency across diverse sectors. This research presents the
multifaceted applications of AI methods and models and their transformative
impact on optimizing energy consumption, reducing energy consumption and
fostering sustainability. One of the primary applications of AI in energy efficiency
lies in predictive analytics. Machine learning algorithms analyse vast datasets,
including historical energy consumption patterns, weather data, and operational
parameters, to forecast future energy demand accurately. These predictive
models enable proactive decision-making, allowing stakeholders to anticipate
fluctuations in energy usage and adjust operations accordingly, thereby
minimizing waste and optimizing resource allocation. Furthermore, AI-driven
optimization models play a crucial role in maximizing energy efficiency. By
formulating complex optimization problems and considering various constraints
and objectives, such as cost minimization, demand satisfaction, and emission
reduction, these models identify optimal solutions for energy-intensive processes.
Whether it's scheduling energy-intensive tasks, optimizing energy distribution in
smart grids, or designing energy-efficient building systems, AI optimization
methods and models offer unprecedented opportunities to enhance efficiency and
sustainability
Object position and orientation detection in assembly tasks – an approach based on YOLOv8 algorithm
No full textAutomated assembly plays a crucial role in today's manufacturing, facilitating high precision, increased efficiency, and reduced production costs. Tasks such as manipulation and mating often require the information about position and orientation of parts. In computer vision-based systems, this information is obtained through image
processing and analysis which can be based on different techniques. Deep learning offers significant advantages over traditional image processing methods, particularly in systems where images are the main source of information. These advantages include enhanced feature extraction capabilities, higher accuracy in recognizing complex patterns, and the ability to learn and improve through the analysis of large datasets. In this work, YOLOv8 model, primarily based on convolutional layers, is employed to identify the position and orientation of objects in the scene. Real-world images were used to fine-tune YOLOv8 model. The performance evaluation was carried out by comparing the ground truth and estimated position and orientation. The application of YOLOv8 model proved to be effective, achieving high position and orientation accuracy
Parametric programming of CNC lathes
No full textParametarsko programiranje CNC mašina spada u napredne tehnike programiranja koje pruža niz
prednosti u odnosu na do sada opšte prihvaćene načine izrade G-kod programa. Proizvođači CNC
mašina i njihovih upravljačkih jedinica su u najvećoj meri koristili ovaj način programiranja za izradu fiksnih ciklusa obrade. I pored niza mogućnosti koje pruža, parametarsko programiranje nije dovoljno zastupljno kod krajnjih korisnika CNC mašina. Programeri CNC mašina ne koriste ovaj način programiranja zbog nedovoljne obučenosti kao i zbog nedostatka literature za edukaciju. U okviru ovoga rada prikazane su osnove parametarskog programiranja CNC mašina. Prema datim
objašnjenjima, može se napisati parametarski program za bilo koju CNC mašinu. U radu su prikazani primeri parametarskih programa napisani za tipske zahvate koji se realizuju na CNC strugu.Parametric programming of CNC machines belongs to advanced programming techniques that provide several advantages compared to the generally accepted ways of creating G-code programs. Until now, manufacturers of CNC machines and their control units have mostly used this way of programming to create fixed processing cycles. Despite the range of possibilities it provides, parametric programming is not sufficiently representative of the end users of CNC machines. CNC machine programmers do not use this way of programming due to insufficient training and a lack of literature for education. This paper presents the basics and principles of parametric programming of CNC machines. According to the explanations, a parametric program can be written for any CNC machine. The paper presents examples of parametric programs written for typical operations realized on a CNC lathe.UDC: 004.42:621.