24 results on '"Dragan Džunić"'
Search Results
2. Tribological Assessment of Aluminum Cylinder Material for Piston Compressors in Trucks and Buses Brake Systems
- Author
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Saša Milojević, Dragan Džunić, Dejan Marić, Tomáš Skrúcaný, Slobodan Mitrović, and Radivoje Pešić
- Subjects
aluminum cylinder ,friction and wear ,piston compressor ,tribological reinforcements ,tribometer ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Applying new technologies to reduce friction and wear in vehicles and equipment can minimize mechanical losses. This reduces power loss in internal combustion engines and reduces fuel consumption and emissions. Consumption of fuel energy can be reduced by the use of light metals, for example aluminum alloy, to produce vehicles and their aggregates and parts. In this case, the problem is poor tribological properties of those light weight metals, as well as the lower strength compared to the cast iron construction. For tribology research purposes, the contact surface of the aluminum cylinder of an experimental piston air compressor is reinforced with inserts of cast iron. The results of tribology research of the composite material are presented in the paper, explaining how parameters such as the sliding speed, contact time and contact area influence friction and wear of the material in relative tribological contacts, under constant normal force. The test procedures were performed on the ball-on-plate CSM® nanotribometer, in linear reciprocating sliding conditions with no lubricant. Material composition of the samples was determined using the Energy-Dispersive Spectroscopy. All measurements were realized at the Faculty of Engineering, University of Kragujevac.
- Published
- 2021
- Full Text
- View/download PDF
3. NANOINDENTATION OF ZIRCONIUM DENTAL CERAMIC PREPARED WITH DIFFERENT FINISHING TECHNIQUES
- Author
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Marko PANTIĆ, Dragan DŽUNIĆ, Miroslav BABIĆ, Slobodan MITROVIĆ, Suzana PETROVIĆ SAVIĆ, Aleksandar ĐORĐEVIĆ, and Aleksandra KOKIĆ ARSIĆ
- Subjects
zirconium ,nanoindentation ,different finishing techniques: polishing ,glazing ,grinding ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
This paper describes the nanomechanical characteristics of Zirconium (IPS e.max ZirCAD, Ivoclar Vivadent) treated with three different surface finishing techniques: polishing, glazing and grinding, using the Anton Paar nanoindentation. The hardness (HV) and Elastic modulus (E) of the surface structure were presented as results of nanoindentation measurements. Nanoindentation tests were done using Berkovich diamond pyramid and the experiment was organized in a 3x4 array. Indentation imprints were investigated using the optical and Atomic Force Microscopy. Also, AFM analysis was used in order to present the 3D surface topography and roughness parameter Ra. The obtained results show that the nanomechanical properties mostly depend of finishing technique.
- Published
- 2019
- Full Text
- View/download PDF
4. PREDICTING CUTTING PARAMETERS BY APPLYING DEVELOPED NEURAL NETWORK AND LINEAR REGRESSION MODELS
- Author
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Aleksandar ĐORĐEVIĆ, Milan ERIĆ, Miladin STEFANOVIĆ, Slobodan MITROVIĆ, Marko PANTIĆ, Aleksandra KOKIĆ ARSIĆ, and Dragan DŽUNIĆ
- Subjects
cutting parameters ,prediction model ,neural networks ,linear regression. ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The paper presents the methods for prediction of the cutting parameters. In order to test the workability of the material by process of scraping, from the aspect of the cutting temperature, an natural thermopar was placed just below the cutting edge of the plate. In this way, a simple, reliable, accurate and economical method for determining the workability of material by cutting is obtained. The feasibility study of several semi-finished products by applying the realized experiments was carried out. Different materials in processing with cutting discs with different coatings give different results, which are used to form neural network and linear regression models.
- Published
- 2019
- Full Text
- View/download PDF
5. ASSESSMENT OF TRIBOLOGICAL BEHAVIOUR OF ZA-27 ZINCALUMINIUM ALLOY BASED NANOCOMPOSITE
- Author
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Dragan DžUNIĆ, Marko PANTIĆ, Slobodan MITROVIĆ, Miroslav BABIĆ, Suzana PETROVIĆ SAVIĆ, Aleksandar ĐORĐEVIĆ, and Aleksandra KOKIĆ ARSIĆ
- Subjects
za-27 alloy ,nanocomposite ,al2o3 nanoparticles ,dry sliding ,friction ,wear ,mml ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Mechanical and tribological investigation of obtained nanocomposites is presented in this paper. As matrix material, well known tribological zinc-aluminium alloy, ZA-27 was used. Nanocomposites were obtained by compocasting procedure, while as reinforcement Al2O3 nanoparticles with average size of 20-30 nm was used. Nanocomposites with three different volume fractions were obtained. In order to get insight in structure and mechanical properties of obtained nanocomposites density and hardness measurements were performed. Tribological properties of tested materials were investigated using block-on-disc tribometer in dry sliding conditions with variation three different values of sliding speed and normal load. Wear tracks that were generated as a result of dry sliding process were analysed using optical and scanning electron with EDS microscope.
- Published
- 2019
- Full Text
- View/download PDF
6. OPTIMIZATION OF MECHANICAL LOSSES IN RECIPROCATING AIR COMPRESSOR WITH CYLINDER CONSISTING OF ALUMINUM ALLOY
- Author
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Saša MILOJEVIĆ, Dragan DŽUNIĆ, Dragan TARANOVIĆ, Radivoje PEŠIĆ, and Slobodan MITROVIĆ
- Subjects
aluminum ,cylinder liner ,friction ,mechanical losses ,reciprocating compressors ,transport ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Transport is largely dependent on oil because the majority of transport vehicles are propelled by engines combusting petroleum products-hydrocarbon fuels. This particularly relates to road, air and water transport. Power losses in the internal combustion engines and other reciprocating machines are mainly engaged to overcome friction. If using aluminum alloys for producing of piston and cylinders in engines and compressors, the results are lower fuel consumption and exhaust emission, firstly because of lower weight and mechanical losses, too. The problems are poor tribological characteristics and lower strength of unprotected aluminum comparing with gray cast iron. For research purposes, the inner surface of cylinder which was produced of aluminum was reinforced by integrating tribological inserts. In this paper, the tribological properties of ferrous based reinforcements were analyzed and compared with aluminum alloy as a base material for cylinder liner and piston skirt in air brake compressor. The ball-on-plate CSM tribometer was used to carry out these tests under dry sliding conditions. In addition to tribological, have carried out and testing of experimental reciprocating compressor on the bench, in the laboratory for engines and compressors in Faculty of Engineering in Kragujevac.
- Published
- 2019
- Full Text
- View/download PDF
7. TRIBOLOGICAL BEHAVIOUR OF A356/SIC NANOCOMPOSITE
- Author
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Sandra VELIČKOVIĆ, Blaža STOJANOVIĆ, Aleksandar VENCL, Miroslav BABIĆ, Dragan DŽUNIĆ, Marko PANTIĆ, and Veljko ŠLJIVIĆ
- Subjects
nanocomposite ,wear rate ,silicon carbide ,aluminium ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The paper presents tribological behaviour of aluminium nanocomposite A356/SiC produced by the compocasting process with mechanical alloying preprocessing (ball milling). Tribological tests were performed on tribometer with block-on-disc contact geometry under lubricated sliding conditions. Influence of amount of silicon carbide reinforcement (0, 0.2, 0.3 and 0.5 wt.%) on wear rate was investigated in the following testing conditions: sliding speed of 0.25 and 1.0 m/s, normal load of 40 N and 100 N and at sliding distance of 1000 m. Analysis of worn surface of nanocomposites was performed by using SEM equipped with EDS.
- Published
- 2019
- Full Text
- View/download PDF
8. WEAR RESISTANCE UNDER DRY CONDITIONS OF DIFFERENT FILLER METALS USED FOR HARD FACING
- Author
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Dušan ARSIĆ, Vukić LAZIĆ, Dragan DŽUNIĆ, Srbislav ALEKSANDROVIĆ, Milan ĐORĐEVIĆ, Milan UHRIČIK, and Aleksandra ARSIĆ
- Subjects
hard facing ,filler metals ,hardness ,microstructure ,wear volume ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The aim of this paper is to show wear properties of different types of filler metals aimed for hard facing and exploitation in dry condition. Testing of wear resistance is done in laboratory on prepared samples/models in order to simulate real exploitation conditions. Samples were made by hard facing of carbon steel using 4 different filler metals. Hard facing was done by using MMA welding method in three layers with enough height so samples could be made. After samples were made, the hardness and microstructure of all zones of hard facing were determined. Testing of wear resistance is done using block on disc contact on samples made from pure weld metal. As a parameter for estimates of the wear resistance of models it was used volume of worn material in mm3. Metallographic investigations and hardness measurements were used as additional parameter for drawing the conclusions.
- Published
- 2019
- Full Text
- View/download PDF
9. Tool geometry effect on material flow and mixture in FSW
- Author
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Nada Ratković, Živana Jovanović Pešić, Dušan Arsić, Miloš Pešić, and Dragan Džunić
- Subjects
General Earth and Planetary Sciences ,General Environmental Science - Abstract
FSW is a solid-state joining process. It is widely used for joining hard alloys like steel, titanium, and aluminium which are very difficult to join by fusion welding. FSW joint quality is mainly influenced by shoulder and pin geometry, its diameter, tool material, tool rotation speed, and linear traveling speed. The paper presents a brief overview of the tools used during the FSW procedure. The influence of the tool pin on the material flow and mixture was analysed in detail. In addition, the primary and secondary material flow and how it is affected by the shape and dimensions of the tool pin are also discussed.
- Published
- 2022
10. DEVELOPMENT OF DEVICES FOR TESTING DYNAMIC DURABILITY OF MATERIALS
- Author
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Vladimir Kočović, Suzana Petrović Savić, Dragan Džunić, Aleksandra Ivanović, Bogdan Živković, and Sonja Kostić
- Subjects
Computer Networks and Communications ,Hardware and Architecture ,Software - Published
- 2022
11. Influence of Vanadium Content on the Tribological Behaviour of X140CrMo12-1 Air-Hardening Steel
- Author
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Aleksandar Todić, Milan T. Djordjević, Dušan Arsić, Dragan Džunić, Vukić Lazić, Srbislav Aleksandrović, and Božidar Krstić
- Subjects
Mechanics of Materials ,fungi ,technology, industry, and agriculture ,air-hardening steel ,vanadium ,impact toughness ,hardness ,wear resistance - Abstract
The paper presents experimental testing of wear resistance of steel samples from the same groups of steel. Test results were recorded and presented in the form of diagrams showing the wear resistance of the tested materials in different sliding conditions. The tested steels have high carbon content; the addition of chromium and molybdenum results in the high hardness and low impact toughness of the steels. The addition of vanadium changes the microstructure when the metal grain becomes smaller and the whole structure is martensitic, with chromium and vanadium carbides in the metal matrix. A change in the microstructure causes a change in mechanical properties. The obtained results showed that the addition of vanadium increases impact toughness. However, it is not known how it affects wear resistance and hardness. This type of steel belongs to a new group of steels resistant to wear. A change in the vanadium content causes a decrease in the hardness and wear resistance of the steel and an increase in its impact toughness.
- Published
- 2022
12. TESTING OF WEAR IN CONTACT WITH STRENX 700 AND AUTOFRETTED STEEL
- Author
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Milan Simonović, Slobodan Mitrović, and Dragan Džunić
- Published
- 2020
13. ASSESSMENT OF TRIBOLOGICAL BEHAVIOUR OF ZA-27 ZINCALUMINIUM ALLOY BASED NANOCOMPOSITE
- Author
-
Marko Pantić, Aleksandra Kokić Arsić, Mitrović Babić, Suzana Petrović Savić, Slobodan Mitrović, Dragan Džunić, and Aleksandar Đorđević
- Subjects
wear ,Nanocomposite ,Materials science ,nanocomposite ,Alloy ,friction ,mml ,za-27 alloy ,General Medicine ,Tribology ,engineering.material ,lcsh:TA1-2040 ,engineering ,Composite material ,al2o3 nanoparticles ,lcsh:Engineering (General). Civil engineering (General) ,dry sliding - Abstract
Mechanical and tribological investigation of obtained nanocomposites is presented in this paper. As matrix material, well known tribological zinc-aluminium alloy, ZA-27 was used. Nanocomposites were obtained by compocasting procedure, while as reinforcement Al2O3 nanoparticles with average size of 20-30 nm was used. Nanocomposites with three different volume fractions were obtained. In order to get insight in structure and mechanical properties of obtained nanocomposites density and hardness measurements were performed. Tribological properties of tested materials were investigated using block-on-disc tribometer in dry sliding conditions with variation three different values of sliding speed and normal load. Wear tracks that were generated as a result of dry sliding process were analysed using optical and scanning electron with EDS microscope.
- Published
- 2019
14. PREDICTING CUTTING PARAMETERS BY APPLYING DEVELOPED NEURAL NETWORK AND LINEAR REGRESSION MODELS
- Author
-
Marko Pantić, Dragan Džunić, Milan Eric, Aleksandar Đorđević, Aleksandra Kokić Arsić, Slobodan Mitrović, and Miladin Stefanovic
- Subjects
prediction model ,Artificial neural network ,Computer science ,lcsh:TA1-2040 ,Linear regression ,General Medicine ,Data mining ,cutting parameters ,linear regression ,computer.software_genre ,neural networks ,lcsh:Engineering (General). Civil engineering (General) ,computer - Abstract
The paper presents the methods for prediction of the cutting parameters. In order to test the workability of the material by process of scraping, from the aspect of the cutting temperature, an natural thermopar was placed just below the cutting edge of the plate. In this way, a simple, reliable, accurate and economical method for determining the workability of material by cutting is obtained. The feasibility study of several semi-finished products by applying the realized experiments was carried out. Different materials in processing with cutting discs with different coatings give different results, which are used to form neural network and linear regression models.
- Published
- 2019
15. WEAR RESISTANCE UNDER DRY CONDITIONS OF DIFFERENT FILLER METALS USED FOR HARD FACING
- Author
-
Milan Uhričik, M. Đorđević, Dragan Džunić, Srbislav Aleksandrović, Vukić Lazić, Dušan Arsić, and Aleksandra Arsic
- Subjects
Wear resistance ,Filler (packaging) ,Materials science ,lcsh:TA1-2040 ,microstructure ,wear volume ,hard facing ,filler metals ,General Medicine ,Composite material ,lcsh:Engineering (General). Civil engineering (General) ,hardness - Abstract
The aim of this paper is to show wear properties of different types of filler metals aimed for hard facing and exploitation in dry condition. Testing of wear resistance is done in laboratory on prepared samples/models in order to simulate real exploitation conditions. Samples were made by hard facing of carbon steel using 4 different filler metals. Hard facing was done by using MMA welding method in three layers with enough height so samples could be made. After samples were made, the hardness and microstructure of all zones of hard facing were determined. Testing of wear resistance is done using block on disc contact on samples made from pure weld metal. As a parameter for estimates of the wear resistance of models it was used volume of worn material in mm3. Metallographic investigations and hardness measurements were used as additional parameter for drawing the conclusions.
- Published
- 2019
16. OPTIMIZATION OF MECHANICAL LOSSES IN RECIPROCATING AIR COMPRESSOR WITH CYLINDER CONSISTING OF ALUMINUM ALLOY
- Author
-
Slobodan Mitrović, Radivoje Pesic, Dragan Džunić, Dragan Taranović, and Saša Milojević
- Subjects
Materials science ,Reciprocating compressor ,friction ,Alloy ,chemistry.chemical_element ,General Medicine ,engineering.material ,Cylinder (engine) ,law.invention ,chemistry ,cylinder liner ,lcsh:TA1-2040 ,Aluminium ,law ,aluminum ,transport ,engineering ,mechanical losses ,Composite material ,lcsh:Engineering (General). Civil engineering (General) ,reciprocating compressors - Abstract
Transport is largely dependent on oil because the majority of transport vehicles are propelled by engines combusting petroleum products-hydrocarbon fuels. This particularly relates to road, air and water transport. Power losses in the internal combustion engines and other reciprocating machines are mainly engaged to overcome friction. If using aluminum alloys for producing of piston and cylinders in engines and compressors, the results are lower fuel consumption and exhaust emission, firstly because of lower weight and mechanical losses, too. The problems are poor tribological characteristics and lower strength of unprotected aluminum comparing with gray cast iron. For research purposes, the inner surface of cylinder which was produced of aluminum was reinforced by integrating tribological inserts. In this paper, the tribological properties of ferrous based reinforcements were analyzed and compared with aluminum alloy as a base material for cylinder liner and piston skirt in air brake compressor. The ball-on-plate CSM tribometer was used to carry out these tests under dry sliding conditions. In addition to tribological, have carried out and testing of experimental reciprocating compressor on the bench, in the laboratory for engines and compressors in Faculty of Engineering in Kragujevac.
- Published
- 2019
17. TRIBOLOGICAL BEHAVIOUR OF A356/SIC NANOCOMPOSITE
- Author
-
Marko Pantić, Veljko Šljivić, Dragan Džunić, Sandra Veličković, Aleksandar Vencl, Blaža Stojanović, and Miroslav Babic
- Subjects
Nanocomposite ,Materials science ,nanocomposite ,silicon carbide ,lcsh:TA1-2040 ,aluminium ,General Medicine ,Tribology ,Composite material ,lcsh:Engineering (General). Civil engineering (General) ,wear rate - Abstract
The paper presents tribological behaviour of aluminium nanocomposite A356/SiC produced by the compocasting process with mechanical alloying preprocessing (ball milling). Tribological tests were performed on tribometer with block-on-disc contact geometry under lubricated sliding conditions. Influence of amount of silicon carbide reinforcement (0, 0.2, 0.3 and 0.5 wt.%) on wear rate was investigated in the following testing conditions: sliding speed of 0.25 and 1.0 m/s, normal load of 40 N and 100 N and at sliding distance of 1000 m. Analysis of worn surface of nanocomposites was performed by using SEM equipped with EDS.
- Published
- 2019
18. Application of Artificial Neural Network in Biotribological Research of Dental Glass Ceramic
- Author
-
Marko Pantić, Milan Eric, Aleksandar Đorđević, Miroslav Babic, Dragan Džunić, Slobodan Mitrović, and Miladin Stefanovic
- Subjects
Glass-ceramic ,Mathematical modelling ,Artificial neural network ,Computer science ,lcsh:Mechanical engineering and machinery ,Mechanical Engineering ,Computer Science::Neural and Evolutionary Computation ,Surfaces and Interfaces ,Physics::Geophysics ,Surfaces, Coatings and Films ,law.invention ,Mechanics of Materials ,law ,Tribological characteristics ,lcsh:TJ1-1570 ,Composite material ,Dental glass ceramic ,Neural networks - Abstract
A tribological system is a complex non-linear system composed of the elements that are connected structurally and functionally. The aim of this paper is to present an overview of artificial neural networks, its development and applications of neural networks in the prediction of tribological properties of dental glass ceramic using a newly measured ball-on-plate nanotribometer. The possibility of artificial neural networks application to solve complex nonlinear problems and to identify tribological characteristics of dental glass ceramic in terms of wear rate and coefficient of friction is presented.
- Published
- 2018
19. Tribological Assessment of Aluminum Cylinder Material for Piston Compressors in Trucks and Buses Brake Systems
- Author
-
Dejan Marić, Radivoje Pesic, Tomáš Skrúcaný, Slobodan Mitrović, Saša Milojević, and Dragan Džunić
- Subjects
Truck ,Reciprocating compressor ,Materials science ,General Engineering ,Mechanical engineering ,aluminum cylinder ,tribometer ,Tribology ,Engineering (General). Civil engineering (General) ,tribological reinforcements ,law.invention ,Cylinder (engine) ,Piston ,friction and wear ,law ,Brake ,piston compressor ,TA1-2040 ,Gas compressor ,Tribometer - Abstract
Applying new technologies to reduce friction and wear in vehicles and equipment can minimize mechanical losses. This reduces power loss in internal combustion engines and reduces fuel consumption and emissions. Consumption of fuel energy can be reduced by the use of light metals, for example aluminum alloy, to produce vehicles and their aggregates and parts. In this case, the problem is poor tribological properties of those light weight metals, as well as the lower strength compared to the cast iron construction. For tribology research purposes, the contact surface of the aluminum cylinder of an experimental piston air compressor is reinforced with inserts of cast iron. The results of tribology research of the composite material are presented in the paper, explaining how parameters such as the sliding speed, contact time and contact area influence friction and wear of the material in relative tribological contacts, under constant normal force. The test procedures were performed on the ball-on-plate CSM® nanotribometer, in linear reciprocating sliding conditions with no lubricant. Material composition of the samples was determined using the Energy-Dispersive Spectroscopy. All measurements were realized at the Faculty of Engineering, University of Kragujevac.
- Published
- 2021
20. Tribological behavior of four types of filler metals for hard facing under dry conditions
- Author
-
Dragan Džunić, Slobodan Mitrović, Srbislav Aleksandrović, Vukić Lazić, Milan Djordjević, Dušan Arsić, and Branislav Nedeljković
- Subjects
Filler metal ,Carbon steel ,business.industry ,Mechanical Engineering ,Abrasive ,Metallurgy ,Mechanical engineering ,02 engineering and technology ,Tribology ,engineering.material ,021001 nanoscience & nanotechnology ,Microstructure ,Surfaces, Coatings and Films ,020303 mechanical engineering & transports ,General Energy ,0203 mechanical engineering ,Filler (materials) ,Service life ,engineering ,0210 nano-technology ,business ,Base metal - Abstract
Purpose The purpose of this study is to show which filler metal is the best for hard facing. Because the quality of the surface layer has a great influence on the working life of parts, the purpose was to extend the working life of parts exposed to intensive wear. The tested hard-faced models were made of low carbon steel to save the expensive base metal and to analyze the possibilities of extending the service life of existing structural parts. Design/methodology/approach Samples were prepared from plates hard faced with various filler metals. Samples were then subjected to experimental testing – testing of tribological properties and hardness and microstructure. Testing was done in conditions similar to real ones – with a sliding speed of 0.25, 0.5 and 1 m/s and with a load of 50, 75 and 100 N and in most rigorous dry conditions. Research was done by using a combination of experimental and theoretical approaches. Findings The paper shows the results of the experimental testing of four different filler metals aimed for hard facing of parts exposed to highly intensive wear. Results shown that CrWC 600 alloy is the most favorable filler metal for hard facing of parts such as those of construction mechanization and those subjected to intensive abrasive wear at stone mines. Practical implications All obtained results are real and fully applicable, as there is a huge industrial need for these types of technologies. With the application of these technologies, beside money savings, the working life of parts can be significantly extended. Originality/value The research presented in this paper was conducted because of the lack of results from this area in Serbia and because of the necessity for application of obtained results in companies for road maintenance and stone excavation in the region of Šumadija, Serbia.
- Published
- 2016
21. Estimation of the Cartilage Volume Loss Due to Knee Osteoarthritis - Case Study
- Author
-
Suzana Petrovic Savic, Nikola Prodanovic, Vladimir Kocovic, Tijana Prodanovic, Dragan Dzunic, Branko Ristic, and Goran Devedzic
- Subjects
osteoarthritis ,reverse engineering ,cartilage ,wear volume ,wear area ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
Osteoarthritis (OA) is a degenerative disease of the knee joint caused by the formation of cracks within the collagen fibers of the articular cartilage. Current research is directed towards less invasive procedures for treating this degenerative disease using tissue engineering and 3D bioprinting. Therefore, it is crucial to obtain the exact shape of the damaged tissue, reconstruct the original shape of the tissue, and estimate the volume and area resulting from the wear of the contact surfaces. The study used the tibial plateau of a patient with OA that was removed during total knee arthroplasty, and the data was collected using a 3D scanner. After the reconstruction of the tibial plateau, an assessment of the area and volume of wear on the medial condyle of the tibia was performed, along with a FEM analysis of the real and approximate shape of the cartilage tissue. In this way, it is possible to simulate and create a patient-specific 3D model with a reconstructed wear volume, which can be highly attractive for future treatment strategies for cartilage damage or early stages of OA.
- Published
- 2023
- Full Text
- View/download PDF
22. Tribological Behavior of Composites Based on ZA-27 Alloy Reinforced with Graphite Particles
- Author
-
Mitrović Slobodan, Bobić Ilija, Branislav Jeremic, Miroslav Babic, and Dragan Džunić
- Subjects
Materials science ,Scanning electron microscope ,Mechanical Engineering ,Alloy ,Composite number ,02 engineering and technology ,Surfaces and Interfaces ,Graphite particles ,engineering.material ,Tribology ,021001 nanoscience & nanotechnology ,ZA-27 alloy ,Surfaces, Coatings and Films ,Matrix (geology) ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Mechanics of Materials ,engineering ,Lubrication ,Graphite ,Tribological behavior ,Composite material ,0210 nano-technology ,Composites ,Tribometer - Abstract
The objective of this investigation is to assess the influence of graphite reinforcement on tribological behavior of ZA-27 alloy. The composite with 2 wt% of graphite particles was produced by the compocasting procedure. Tribological properties of unreinforced alloy and composite were studied, using block-on-disk tribometer, under dry and lubricated sliding conditions at different specific loads and sliding speeds. The worn surfaces of the samples were examined by the scanning electron microscopy (SEM). The obtained results revealed that ZA-27/graphite composite specimens exhibited significantly lower wear rate and coefficient of friction than the matrix alloy specimens in all the combinations of applied loads (F n ) and sliding speeds (v) in dry and lubricated tests. The positive tribological effects of graphite reinforcement of ZA-27 in dry sliding tests were provided by the tribo-induced graphite film on the contact surface of composite. In test conditions, characterized by the small graphite content and modest sliding speeds and applied loads, nonuniform tribo-induced graphite films were formed leading to the increase of the friction coefficient and wear rate, with increase of the sliding speed and applied load. In conditions of lubricated sliding, the very fine graphite particles formed in the contact interface mix with the lubricating oil forming the emulsion with improved tribological characteristics. Smeared graphite decreased the negative influence of F n on tribological response of composites, what is manifested by the mild regime of the boundary lubrication, as well as by realization of the mixed lubrication at lower values of the v/F n ratio, with respect to the matrix alloy.
- Published
- 2009
23. Effect of Fiber Orientation on the Tribological Performance of Abaca-Reinforced Epoxy Composite under Dry Contact Conditions
- Author
-
Marko Milosevic, Dragan Dzunic, Petr Valasek, Slobodan Mitrovic, and Alessandro Ruggiero
- Subjects
epoxy resin ,abaca fiber ,fiber orientation ,natural composites ,friction ,wear ,Technology ,Science - Abstract
This paper presents tribological research of an abaca fiber-reinforced epoxy composite material, analyzing fiber orientation and its effect on the tribological performances of the composite. The extremely low viscosity epoxy resin reinforced with NaOH-treated long abaca fibers is investigated under the different operating conditions. The unidirectional abaca fibers reinforced the epoxy resin and formed composite specimens with fibers in three directions, parallel (P-O), anti-parallel (AP-O) and normal (N-O), while keeping the sliding direction. The specimens were fabricated using fiber volume fractions of 10 vol%, 20 vol% and 30 vol% using the vacuum infusion technique. The block-on-disc (BOD) apparatus has been used to exhibit the tribological tests. Normal loads of 35 N and 45 N have been used for testing purposes. The experimental results indicated that the presence of abaca fiber significantly improved the wear characteristics of the matrix. An increased coefficient of friction was observed in samples with anti-parallel-oriented fibers at an applied load of 35 N. The conducted research shows that the use of abaca fibers as fillers could improve the tribological characteristics of the epoxy resin-based composite material.
- Published
- 2022
- Full Text
- View/download PDF
24. Investigation into the Effects of Roller Pressing on Hardness, Roughness and Elastic Modulus of Wooden Workpieces
- Author
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Vladimir Kocovic, Dragan Dzunic, Sonja Kostic, Ljiljana Brzakovic, Branko Tadic, Miljana Prica, and Djordje Vukelic
- Subjects
roller pressing ,wood ,hardness ,elastic modulus ,roughness ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
The paper investigates the effects of roller pressing on the hardness, roughness, and elastic modulus of wooden workpieces. For research purposes, a roller pressing device based on purely mechanical processing was designed and developed. Four different levels of pressing force have been applied to eight different types of wood: cherry, fir, alder, linden, beech, walnut, oak, and ash. The obtained results indicate that the proposed processing method can significantly improve the hardness, elastic modulus, and surface quality of wooden workpieces. The ash sample exhibited the largest relative increase in hardness (175.9%), while the most significant relative increase in the elastic modulus (66.73%) was measured on the linden sample. The largest relative decrease in surface roughness (54.75%) was achieved on the alder sample. For all types of wood except for fir, in which case an increase in pressing force did not produce the desired reduction of roughness, correlation coefficients indicate a strong relationship between the pressing force as an input variable and the elastic modulus, hardness, and roughness as output variables.
- Published
- 2022
- Full Text
- View/download PDF
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