gep20232-3borito2-3/2023

  gep20232-3borito gep20232-3angimp gep20232-3angtart1 gep20232-3angtart2

 

Péter Bozzay, Prof. Dr. Károly Jármai, Dr. Zoltán Virág:
VIBRATION DAMPING MATERIAL BEHAVIOR AT LOW TEMPERATURE 6
Vibration damping plays a vital role in cyclic loading. There are a significant number of different dampers available. Their material properties can change significantly at low temperatures. The research aims to determine the characteristic behaviors of a rubber strap with canvas linings. We determine the loss factor of the material at different temperatures between -50 C° and +20 C°—also the static and the dynamic shear modulus. We use the Brüel & Kjaer measuring devices to change the cyclic loadings and the vibration frequencies. A special refrigerator was available to provide low temperatures down to -60 C°. The measurements were made using fabric conveyor belt specimens.

Imre Marada, Dr. János Bihari:
EQUIPMENT FOR THE ANALYSIS OF FAULTS OF SMALL PLASTIC GEARS 12
In the case of small plastic gears, production volumes and manufacturing processes severely limit the number of methods that can be used to detect faults. It is therefore particularly important to understand the phenomena caused by faults that are also present, detectable, and measurable on the gear shafts. Among the rotational characteristics, the measurement of torque on the input side is a common test method for gear drives, especially for bevel gears. This method is also suitable for detecting certain faults in gearboxes with small gears and for distinguishing the effects of faults and manufacturing characteristics. In this research, we have established the basis and equipment, for a series of measurements that can be used to gather more definitive information than previously known, to understand the effects of faults in small plastic gears.

Tatiane Domokos, Atilla Baksa, Szabolcs Szávai:
FLD WITH GURSON METAL FOR SIMPLE FLAT SPECIMEN 16
In the past, the prediction of ductile damage and fracture of metal materials under complex loadings has been an important topic in industries like the metal forming industry. The GTN model is one of the most classical damage models regarding damage mechanics, which has a wide application and perfect evolution in studies of fracture of ductile metal. GTN was originated from Gurson and later enhanced by Tvergaard and Needleman. The improvement consists of inserting an equivalent void volume fraction f and two more parameters called q1 and q2 into the yield function of Gurson’s model, in order to model the complete loss of load-carrying capacity at a realistic void volume fraction.

Máté Petrik, Betti Bolló, Károly Jármai:
FIRE SAFETY DESIGN OF A TRUCK TANK IN A PUBLIC ROAD ACCIDENT 20
The focus of the research is to determine the fire-resistant time of a truck tank containing different liquids in case of a public road accident. The wall material and the wall thickness of the tank have a significant effect on the fire resistance. Depending on the heat release rate, the process can be rapid. We make the calculations for the given tank dimensions and try to optimize the tank for the necessary fire resistance time R30 and R45.
The vessel on a track cannot be classified as a classic pressure vessel, even though the fluid in the cylindrical shell is already loading hydrostatic pressure on the vessel wall. This is due to the dynamic and fatigue loads resulting from the vehicle’s progress. Typically, two problems can occur in the event of a fire in such a tank. When transporting a flammable liquid, the fire can cause the pressure in the vessel to increase, resulting in the vessel rupturing. The use of safety equipment can avoid this. However, a BLEVE phenomenon may occur if the tank is left on fire for too long; on the other hand, when transporting solid granular materials, the medium is less able to dissipate heat, so the container may weaken under the weight load, which may also result in cracking. If the granular material is combustible, a more severe fire may develop.

Dr. János Bihari, Imre Marada:
TESTING BOLTED CONNECTIONS IN PLASTIC PARTS MADE BY FDM PRINTING 26
FDM and MSLA printing are no longer used as just a tool for prototyping, but many working parts can be produced using these manufacturing technologies. The mechanical properties of these type of parts depend on a number of factors and cannot be as clearly defined, for example for injection molded parts. Since components are often fastened by bolted connections, it is important to know what tightening torques and clamping forces should be used for different materials, in different planes and with different filling ratios. In this research, we aimed to find answers to the question of what clamping forces can be achieved in FDM printed parts with different designs of threaded connections.

Dr. Péter Bencs:
REVIEW OF BUS COOLING SYSTEMS IN THE CONVERSION PROCESS 30
The primary objective of this research is to investigate the cooling/heating solutions for an urban passenger bus engine cooling and battery plant (for electric drive). A general literature review was conducted to assess the thermal performance expected in a sizing process. In the context of literature, an electrical conversion was also examined to see what cooling system is used for internal combustion engines, what system is replaced and what solution is applied. In the research framework, we tried to find specific thermal performance values for a bus (urban passenger bus) defined in the assignment. The next step of the research was to explore the methods used for cooling internal combustion engines. As a final step in the literature review, the cooling and heating solutions for battery packs used in an electrical conversion were considered (maintaining the optimum temperature range of battery packs).

Tamás Géza Molnár, Brigitta Zsótér:
MATERIAL TESTING OF 3D PRINTED INDUSTRIAL PLASTICS IN TECHNICAL PRACTICE 35
Our research was made on 3D printing and the mechanical characteristics of printed plastic components, while examining opportunities for its technical applications. We used various tear test samples with different printing technologies from different stocks, making changes to the printing parameters as well. Ready ISO plastic test bodies were submitted to a tearing examination, pulled according to the 527 standards. We compared the stock result examinations, with the tear characteristics of die-cast products, which resulted on average 25-35% lower, for 3D printed samples. The productivity differences compared to diecast, has a diminished concern because of the freedom to form various shapes and prototypes using 3D printing technology, primarily in small series or merchandising test production. 3D yields a suitable solution in this case. The collected results serve as a basis for printing and modeling of planned components and its sizing.

Dr. Károly Jármai:
MINIMIZING THE WEIGHT, COST AND ENVIRONMENTAL IMPACT OF WELDED STEEL STRUCTURES 46
The article describes how to calculate the environmental impact of steel structures and how different welding technologies cause environmental impacts through the formation of gases during the process. The weight or direct cost of a steel structure can be minimized by optimizing the structure.

Gábor Kónya, Zsolt Ferenc Kovács:
PROBLEMS OF MACHINABILITY OF NICKEL-BASED SUPERALLOYS 54
In this paper, the problems of machinability of nickel-based superalloys are discussed, why machinability of these materials is so difficult, and the importance of R&D for industry. These superalloys are some of the most difficult materials to machine and are widely used as raw materials for gas turbines in the aerospace and energy industries. Based on industry experience, slot milling causes the biggest problem, tools wear quickly and breakages are common. Due to the high thermal strength and hardness, the cutting zone is subjected to high shear stresses, resulting in increased cutting forces, and cutting temperatures, which also stresses the tool edge due to extremely poor thermal conductivity of the material. In this paper, we will briefly summarize why the machinability of these materials is so difficult, and which data influences tool lifespan. Based on our research, we presented the effects of tool paths and cooling-lubricating processes on cutting tool life.

Seif Eddine Habbachi, Attila Baksa, Marwen Habbachi:
NUMERICAL MODELLING OF TRANSVERSE SPRING LEAF WITH STEEL MATERIAL 62
Automobile suspension systems (springs, shock absorbers, linkages) are becoming more important in today’s world, as they contribute to a car’s handling and braking, protect the vehicle itself, and protect cargo or luggage from damage and wear. Furthermore, suspension systems have many functions, like preventing the vehicle body and frame from road shocks, giving it stability, and providing comfort as well. In the meantime, suspension equipment needs to have a lower weight, maximum deflection, low maintenance, and a low operating cost. During this work, we will focus only on the leaf spring suspension type, and more precisely, the transverse leaf spring. Our project is a numerical modelling of the transverse leaf spring, using the finite element method, in order to investigate the maximum deflection and stress distribution along a deformable body with two-common vertical and anti-metrical stiffnesses configurations and compare the results with a theoretical model and with the provided data from Iveco company to validate them. Finally, an important comparison was presented between the numerical results and the provided data. In fact, results show that the structure under the applied force was safe.

László Pokorádi:
UNCERTAINTY ANALYSIS OF REPAIR WORK ESTIMATION BY MONTE-CARLO SIMULATION 67
Maintenance is one of the most important territories of practical engineering. From the mathematical point of view, the operation of production equipment is a discrete state space, stochastic process, without after-effects, i.e., a Markov-chain. The aim of this paper is to discuss the possibilities of using the Monte-Carlo Simulation of repairing processes, to determine necessary maintenance capacity. The proposed method can be implemented for the assessment of required maintenance capacity of a welding cell depending on allowable estimating uncertainty.

Aimen TANOUGAST, Krisztián HRICZÓ:
NUMERICAL SIMULATION OF NANOFLUID FLOW THROUGH A CORRUGATED CHANNEL WITH VORTEX GENERATOR 72
The radiator is an important part of the car, which cools the different parts of the vehicle by indirect heat exchange, by circulating coolant through the radiator. Heat transfer conditions are a function of the flow, geometry, and temperature characteristics. The present work concerns the numerical study of two-dimensional turbulent flow with heat transfer in a corrugated channel, with and without vortex generators, while applying Al2O3-water nanofluid as a heat transfer liquid.
The governing equations of the flow are the continuity equation, the momentum equation, and the energy equation modeling the heat transfer. This partial differential equation system was discretized and solved using the Ansys-Fluent commercial software based on the finite volume method. The standard k-ε model was used to model turbulence.
We analyzed the effect of parameters and the vortex generators on the solutions. The obtained results were presented graphically.

Dávid Bodnár, Károly Jármai:
DESIGN OF ROBOT WORKSPACE AND STRUCTURE, A REVIEW 78
The use of robots for various tasks is growing. In order to identify possible research directions, this paper aims to review the progress achieved in the optimization of workspace, lifetime and structure of robots in industrial or medical applications. Medical applications are considered because of the potential for improved accuracy and control and reduced invasiveness compared to traditional surgical methods. This review will form the basis for future research on the topic, identifying possible research directions using the algorithms and techniques reviewed. The focus is on workspace and structure optimization, with an emphasis on cost-effectiveness.

 

The articles in the current issue of GÉP were reviewed by two professional reviewers. The reviewers were
(without naming the articles):

Bodnár Dávid • Nagy Szilárd • Orbán Ferenc • Szirbik Sándor •
Hanka László • Máté Márton • Tolvaly-Roşca Ferenc •
Pokorádi László • Virág Zoltán • Koós Dániel

 

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