Attila Németh
57203016266
Publications - 17
Quantifying the Effect of Frame Stiffness – The Substitution Inertia of Meier's Calculation
Publication Name: Lecture Notes in Networks and Systems
Publication Date: 2025-01-01
Volume: 1258 LNNS
Issue: Unknown
Page Range: 46-57
Description:
The internationally accepted method for assessing track stability is the calculation based on Meier's theory. A critical point is the inclusion of the equivalent track bending stiffness. Practical measurements have often given contradictory results in determining this, so the authors present a purely theoretical determination in this article. For this purpose, the Nemesdy theory, which is used in Hungarian practice, is invoked. By applying this theory, the paper introduces an auxiliary factor that allows us to calculate the value of the inertia of the two rails on the vertical axis. Stopping at this point in the theoretical derivation and recognizing the possibility, an iterative solution is proposed by which the magnitude of the substitute inertia can be considered in Meier's calculation without performing the necessary calculations using Nemesdy's theory.
Open Access: Yes
Dynamic Modeling Possibilities of Embedded Rail Structures
Publication Name: Acta Polytechnica Hungarica
Publication Date: 2025-01-01
Volume: 22
Issue: 4
Page Range: 29-43
Description:
In Hungarian design practice, the Zimmermann-Eisenmann quasi-static design method is employed to dimension track structures with embedded rails. This method determines the mean values of deformations and stresses using an infinitely long elastically embedded beam as the static frame. After establishing these mean values, the effects of track condition and speed are considered through Eisenmann multiplication, enabling the definition of design values. Conversely, international practices include methods that calculate deformations and stresses based on dynamic models incorporating viscoelastic embedding, directly accounting for speed but not dynamic effects due to track characteristics. This paper presents a solution to the dynamic problem, extending it to studying rotating frames beyond the commonly considered uniaxial solution. Each factor's effect is separately analyzed for track structures with embedded rail tracks, leading to a recommendation for the value of the "load multiplication factor".
Open Access: Yes
Laboratory and Numerical Investigation of Pre-Tensioned Reinforced Concrete Railway Sleepers Combined with Plastic Fiber Reinforcement
Szabolcs Fischer
Mykola Sysyn
Zoltán Major
Sarah Khaleel Ibrahim
Dmytro Kurhan
Vivien Jóvér
Szabolcs Szalai
Hanna Csótár
Klaudia Madarász
András Pollák
Dániel Harrach
Bálint Molnár
L. Gaspar
Bence Hermán
Szabolcs Kocsis Szurke
Attila Németh
I. Fekete
Richárd Nagy
Gusztáv Baranyai
Miklós Kuczmann
M. Movahedi Rad
Publication Name: Polymers
Publication Date: 2024-06-01
Volume: 16
Issue: 11
Page Range: Unknown
Description:
This research investigates the application of plastic fiber reinforcement in pre-tensioned reinforced concrete railway sleepers, conducting an in-depth examination in both experimental and computational aspects. Utilizing 3-point bending tests and the GOM ARAMIS system for Digital Image Correlation, this study meticulously evaluates the structural responses and crack development in conventional and plastic fiber-reinforced sleepers under varying bending moments. Complementing these tests, the investigation employs ABAQUS’ advanced finite element modeling to enhance the analysis, ensuring precise calibration and validation of the numerical models. This dual approach comprehensively explains the mechanical behavior differences and stresses within the examined structures. The incorporation of plastic fibers not only demonstrates a significant improvement in mechanical strength and crack resistance but paves the way for advancements in railway sleeper technology. By shedding light on the enhanced durability and performance of reinforced concrete structures, this study makes a significant contribution to civil engineering materials science, highlighting the potential for innovative material applications in the construction industry.
Open Access: Yes
Investigation of the Vertical Stability of Embedded Rail Structures
Publication Name: Advances in Transdisciplinary Engineering
Publication Date: 2024-01-01
Volume: 59
Issue: Unknown
Page Range: 37-43
Description:
In the case of embedded rail structures, the rails are fixed with a flexible embedding material that runs through a specially designed steel or reinforced concrete channel. The majority of the rail cross-section is embedded in these channels, eliminating the possibility of horizontal buckling as a failure mode. This paper investigates vertical stability, aiming to determine the stability resistance of a rail loaded with an initial failure in the vertical plane while considering elastic resistance. Vertical plane buckling is assumed to be a non-hazard for conventional rails because the wide rail footing can significantly inhibit vertical displacement, even without adhesion between the rail surface and the embedding material. However, the adhesion of the embedding material to the channel is adequate. Some rail sections lack adhesion between the rail and the embedding material due to the narrow width of the rail foot, making the phenomenon of "form-locking" uncertain, or the rail is partially embedded. In this article, the authors present a theoretical calculation method to investigate this problem, to transfer the results to everyday practice as simply as possible, and to present a solution suitable for manual calculation. Measuring the vertical spring constant in the method's input parameters under laboratory conditions is a difficult task, but by utilizing the possibilities provided by finite element modeling, the design can be significantly simplified. The introduced method has the significant advantage of quantifying the effect of vertical plane misalignments in the track compared to simpler solutions in the literature.
Open Access: Yes
DOI: 10.3233/ATDE240524
TESTING THE FRAGMENTATION OF RAILWAY BALLAST MATERIAL BY LABORATORY METHODS USING PROCTOR COMPACTOR
Publication Name: Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu
Publication Date: 2024-01-01
Volume: Unknown
Issue: 1
Page Range: 58-68
Description:
The physical classification of crushed stone and gravel used in railway construction is based on their strength and endurance and is performed by a laboratory test method using a rotating drum or a mortar method. The values of fracture resistance calculated using the Los Angeles method and abrasion calculated using the Micro-Deval method show a corresponding correlation and require further investigation. Purpose. The development of a new method for measuring rock material fracture that is consistent with widely used standards while also being more comparable to real-world railway operating conditions. Certainly, both standard tests are essential for ensuring product homogeneity during production, so the new recommended method is only a supplement. Methodology. The Proctor device was used to induce so-called shock loads from above, similar to railway loading conditions. Unlike the standard method, the andesite material was placed in a standard cylinder in these tests. The samples were pre-screened and sorted; the specified weight was approximately 1,300 g, and the specified sizes of the individual particles were 6.3, 8.0 and 11.2 mm. Only prewashed and dried materials of NZ (fine crushed stone) or KZ (special crushed stone) from four different quarries (Tállya, Szob, Nógrádkövesd, Recsk) with different rock physics characteristics were considered. The Proctor compactor machine was used because of its calculable labor (19.86 J/impact) and the crushing effect of the calculable impacts (64, 128, 256 and 1,028 blows). Even after loading different numbers of impacts, homogeneous samples from different quarries were sieved to measure the masses of fragments per fraction. Findings. The set of measurements made it possible to establish a series of fragmentation and degradation curves for each of the three repeated measurements based on the composition of the material and the number of blows, which showed the degradation of samples with different physical and mechanical properties of the rock material and particle sizes. With an increasing number of impacts, the amount of crushed material in the sample increased, but the distribution of crushed material did not decrease evenly and proportionally as the number of impacts increased. Parameters and indices were also computed to identify various correlations (i. e., FV , d < 22.4, d < 0.5, d < 0.063 mm, CU , M ratio, λ ratio). Some of them (e. g., FV ) needed to be changed, but they were predefined due to the nature of the tests. Originality. While many standard and alternative railway track ballast fragmentation test methods and measurement tools are available, this paper proposes a new laboratory method and demonstrates the specific measurement and application effectiveness. Practical value. In addition to standard tests that are already widely used, the new method for measuring the fractional composition of railway ballast can help simulate real-world operating conditions of a railroad track in the laboratory. This method will improve the safety of railway operations.
Open Access: Yes
Investigation of the Geometrical Deterioration of Paved Superstructure Tramway Tracks in Budapest (Hungary)
Publication Name: Infrastructures
Publication Date: 2023-08-01
Volume: 8
Issue: 8
Page Range: Unknown
Description:
In the 21st century, one of the key requirements is to develop and maintain our infrastructure facilities most efficiently using the available resources. Tramways are of significant national economic importance and represent an important national asset. There are currently seven different types of superstructure systems in Hungary, based on the national regulations and the related requirements currently in force. This paper compares the paved tramway superstructure systems in the context of track geometry, through-rolled axle tons of track, and the age of track sections. Paved tracks have many benefits, but the main ones are easier maintenance and road traffic use. Elastically supported continuous rail bedding (ESCRB; in Hungary, this is known as “RAFS”) and “large” slab superstructure systems are used to create paved superstructure systems. Road crossings use the latter systems, while heavily loaded lines use several ESCRB systems. This article examines the geometrical changes in several ESCRB superstructure systems. A TrackScan 4.01 instrument was used to take measurements in June and September 2021 and in April 2022, September 2022, and May 2023. Track gauge, alignment, and longitudinal level are examined. Regardless of the ESCRB superstructure system or age, a medium-loaded line’s track gauge trendline increases, which means that the track gauge is widening and, regardless of traffic load or age, the average longitudinal level is constantly increasing from year to year. When it is a medium-loaded line, the average value of alignment increases slightly, and the trendline is almost straight, but it decreases when it is an extremely heavily loaded line. The authors will analyze how the reference track section will change in the future. Based on the results, it is important to assess how subsequent measurements affect the trend lines. Because the data evaluations show similar results, comparing open tramway tracks to paved ones is crucial.
Open Access: Yes
Optimization of 3D Printed Rapid Prototype Deep Drawing Tools for Automotive and Railway Sheet Material Testing
Publication Name: Infrastructures
Publication Date: 2023-03-01
Volume: 8
Issue: 3
Page Range: Unknown
Description:
The main objective of this research is to identify optimal printing strategies and PLA (polylactic acid) filament materials to produce rapid prototype deep drawing tools. Additive 3D printing technologies have been applied for a long time to produce tools, but the research is unique in that it uses conventional and various reinforced PLA materials with conventional FDM (Fused Deposition Modeling) printers. The advantage of this method is that PLA is easy to print and recycle and does not require expensive or special printers, this also gives the article its novelty. A further aim was to produce the tools using commercially available low-end printers. DX53D 0.8 mm thick body steel and AlMg3 2.5 mm thick sheet were the materials to be molded for the tests. The test tool was an Erichsen deep drawing punch. Tool wear was tested using the GOM ATOS measuring system, an optical coordinate measuring machine based on the DIC (Digital Image Correlation) principle, which is also popular in the automotive industry. The study aims to determine the 3D printing and material parameters that can safely produce a minimum batch of 100 parts.
Open Access: Yes
Numerical Investigation of Pre-Stressed Reinforced Concrete Railway Sleeper for High-Speed Application
Publication Name: Infrastructures
Publication Date: 2023-03-01
Volume: 8
Issue: 3
Page Range: Unknown
Description:
The current paper deals with the numerical investigation of a unique designed pre-stressed reinforced concrete railway sleeper for the design speed of 300 km/h, as well as an axle load of 180 kN. The authors applied different methodologies in their research: traditional hand-made calculations and two types of finite element software. The latter were AxisVM and ABAQUS, respectively. During the calculations, the prestressing loss was not considered. The results from the three methods were compared with each other. The hand-made calculations and the finite element modeling executed by AxisVM software are adequate for determining the mechanical inner forces of the sleeper; however, ABAQUS is appropriate for consideration of enhanced and sophisticated material models, as well as the stress-state of the elements, i.e., concrete, pre-stressed tendons, etc. The authors certified the applicability of these methodologies for performing the dimensioning and design of reinforced concrete railway sleepers with pre-stressing technology. The research team would like to continue their research in an improved manner, taking into consideration real laboratory tests and validating the results from FE modeling, special material models that allow calculation of crackings and their effects in the concrete, and so that the real pattern of the crackings can be measured by GOM Digital Image Correlation (DIC) technology, etc.
Open Access: Yes
Optimization of Surface Preparation and Painting Processes for Railway and Automotive Steel Sheets
Publication Name: Infrastructures
Publication Date: 2023-02-01
Volume: 8
Issue: 2
Page Range: Unknown
Description:
The article deals with DIC (Digital Image Correlation) tests on steel plates used in the automotive and railway industries, as well as in the construction industry. The most critical part of DIC tests is the quality of proper surface preparation, painting, and random patterns. The paint mediates the deformation of the optical systems, and its quality is paramount. The authors’ goal in this research is to determine the optimal dye–cleaning–drying time parameters for DIC studies. Commercially available surface preparation and cleaning agents were tested alongside commercially available spray paints. Standard and specific qualification procedures were applied for the measurements. Once the appropriate parameters were determined, the results were validated and qualified by GOM ARAMIS tests. Based on the results, DIC measurements can be performed with higher accuracy and safety in laboratorial and industrial conditions, compared to the traditional deformation measurements executed by dial gauges or linear variable differential transformers.
Open Access: Yes
Investigation of “Open” Superstructure Tramway Tracks in Budapest
Publication Name: Infrastructures
Publication Date: 2023-02-01
Volume: 8
Issue: 2
Page Range: Unknown
Description:
The most important thing nowadays is to use available resources to develop infrastructure as efficiently as possible. In this regard, evaluating the deterioration of tramway tracks is critical from both a technical and an economic viewpoint. In Hungary, seven types of superstructure systems are currently differentiated in the case of tramway transport, but the geometrical deterioration, lifecycle, and lifecycle cost of the tramway tracks are not accurately known. The current study aimed to evaluate and compare the results of track geometry measurements of two different “open” tramway superstructure systems depending on their traffic load and age. The geometry measurements we re executed by TrackScan 4.01 instrument, developed and maintained by a Hungarian developer company called Metalelektro Méréstechnika Ltd. The evaluation of the measurements showed a clear relationship between the traffic load, age, and track deterioration. Based on the results, it can be generally stated, concerning “open” superstructure systems, that regardless of the “open” superstructure system or the level of traffic load, the average value of alignment is decreasing; however, the average value of the longitudinal level is increasing. Furthermore, the deterioration of an older ballasted track with lower traffic is similar to that of a younger ballasted track that has a higher traffic load. Another significant result was that the deterioration of the track gauge parameter in the case of concrete slab tracks is clearly described as the broadening of the track gauge.
Open Access: Yes
Optimization of Surface Cleaning and Painting Methods for DIC Measurements on Automotive and Railway Aluminum Materials
Publication Name: Infrastructures
Publication Date: 2023-02-01
Volume: 8
Issue: 2
Page Range: Unknown
Description:
The preparatory operations of DIC (Digital Image Correlation) tests were investigated in this study, with special emphasis on specimen cleaning and painting operations. As it is well known, DIC tests are non-contact and applied in materials research, the analysis of complex structures, and, nowadays, the construction industry. The use of DIC technologies has seen a dynamic increase in all scientific fields. In our study, aluminum body panels for automotive and railway applications were tested using this technique. There are many articles on proper patterning in the literature but fewer on preparation and priming. These are critical for a successful DIC measurement. This paper looks at different surface cleaners and primers with different grading procedures and will also determine the time window within which the paint should be applied. Finally, the GOM ARAMIS system was applied to measure and characterize the painted surface and visible deformation defects resulting from inadequate painting.
Open Access: Yes
Testing of Lubricants for DIC Tests to Measure the Forming Limit Diagrams of Aluminum Thin Sheet Materials
Publication Name: Infrastructures
Publication Date: 2023-02-01
Volume: 8
Issue: 2
Page Range: Unknown
Description:
We investigated lubricants and thin teflon foils that can be applied in the formability testing of the thin aluminum sheets used in the electronics and automotive industries. For the tests, thirteen different industrial lubricants (oils and greases) (i.e., L1–L13) and two Teflon films (i.e., 0.08 and 0.22 mm thick) were applied. The authors conducted an Erichsen test, and the thickness reduction of the discs was measured first. In forming-limit curve (FLC) tests, it is crucial that the stresses are localized in the central area of the specimen during forming and that biaxial deformation is maintained throughout, if possible. We aimed to achieve and fulfill this task. To perform this measurement, the GOM ARAMIS measuring system was utilized. It is an optical measuring system based on the digital image correlation (DIC) principle, capable of measuring both stresses and displacements in real time. A specific validation method was also developed to qualify the DIC system. We concluded that there was a 5% difference in Erichsen indentation (IE) number diagrams between the best (L12) and worst (L4) cases for the lubricants and oils tested, which is a significant difference for thin plates. We found that this value could be increased and improved by using Teflon discs. Furthermore, the localization of stress maxima, i.e., the centering of cracks in the specimen, could be achieved by combining Teflon discs and L12 lubricant (with appropriate layer order), which significantly aids in the recording of standard FLC diagrams. Using foils is also advantageous because they are readily available, have no expiry date, and are of less environmental concern.
Open Access: Yes
Comparative Life Cycle Analyses of Regular and Irregular Maintenance of Bridges with Different Support Systems and Construction Technologies
Publication Name: Chemical Engineering Transactions
Publication Date: 2022-01-01
Volume: 94
Issue: Unknown
Page Range: 571-576
Description:
The maintenance cost of bridges is huge in every country e. g. in the USA it is (approx.) 41.8 G$. This causes a 6.2 % GHG emission rise annually. Reducing and minimizing cost, GHG level and CO2 pollution is a key factor and a major goal for sustainability. This study presents a comparative life cycle assessment (LCA) of bridges with different support systems and construction technologies but with the same span and location. LCA considers regular and irregular bridge maintenance as well having a great influence on the need and timing for major maintenance or restoration in every 25 to 30 y. Regular maintenance means every 1 - 5 and 10 - y minor maintenance works take place. The analysis is based on primary data collected in Hungary examining fully constructed bridges. For the LCA, the cost of maintenance over a 100 y timespan is based on NIF regulations, the total rate of CO2 pollution and the EF (Ecological Footprint, Gha) level is used (Long et al., 2020;). In practice the maintenance of the bridges take place occasionally when the damage on the bridges are already visible and cannot be postponed based on the in - depth interviews with experts. It is assumed that the cost, EF and CO2 pollution of the regular maintenance over the examined timespan is less compared to results of the irregular life cycle model. Based on the case study presented, it can be concluded that the cost of LCA for regular bridge maintenance is 637,348.32 (k€) and for irregular bridge maintenance it is 994,415.12 (k€). The CO2 pollution for regular bridge maintenance is 12,948.24 (kt) and for irregular bridge maintenance is 13,876.86 (kt). The EF pollution for regular bridge maintenance is 3,237.06 (kGha) and for irregular bridge maintenance it is 3,469.22 (kGha). Considering the long - term sustainability aspects, it is recommended that the maintenance should be a regular and a controlled activity. It is vital to draw the attention of the decision makers, the legislators of the businesses, the maintenance operators, and the inspectors to these sustainability aspects.
Open Access: Yes
DOI: 10.3303/CET2294095
Investigation of the Track Gauge in Straight Sections, Considering Hungarian Railway Lines
Publication Name: Acta Polytechnica Hungarica
Publication Date: 2022-01-01
Volume: 19
Issue: 3
Page Range: 155-166
Description:
In this work, considering the MÁV’s (i.e., the Hungarian Railways) five small and five high-traffic railway lines, the statistical distribution and change of the track gauge parameter were analyzed, under a ten year, on time-series analysis, related to straight track sections. The analysed data, were bottom track gauge measurements, of the FMK-004 and FMK-007 type railway track geometry, measuring and recording car & wagon. Taking into account the railway tracks, the track gauge parameter cannot be controlled and improved upon by large machine methods, but its permitted value depends on the allowed speed (and vice versa). The main independent variables were the elapsed time and the through-rolled axle tons (as a function of time, i.e., the MGT). To generate the statistical analyses, Vaszary-like shape numbers were computed, considering the distribution functions of the measured data series of the track gauge parameter every 25 cm. The authors examined the change of the shape numbers, the average and standard deviation values of the track gauge, and the shape of the distribution functions (skewness and kurtosis properties). In the end, a spectrum analysis of the measured data series was produced. In conclusion, the Authors provide relevant statements regarding the track gauge parameter.
Open Access: Yes
DOI: DOI not available
Investigation of deformations of ballasted railway track during collapse using the Digital Image Correlation Method (DICM)
Publication Name: Reports in Mechanical Engineering
Publication Date: 2022-01-01
Volume: 3
Issue: 1
Page Range: 168-191
Description:
This paper summarizes the results of laboratory tests in which the authors investigated the effects of extremely high vertical load to a railway track segment. The segment consisted of a cut concrete sleeper (contact area: 290×390 mm) with a pair of direct-elastic rail fasteners; the sleeper pieces had a standard, full height; the structure had a typical 350 mm depth railway ballast, underneath approx. 200 mm sandy gravel supplementary layer. The whole assembly was built in a 2.00×2.20 m area wooden rack. The deformations due to the approx. 150 kN static concentrated vertical force were measured and recorded by Digital Image Correlation Method (DICM), ensuring the GOM ATOS technology. The 150 kN peak load meant 1326 kPa vertical stress at the sleeper-ballast interface. The 3D geometry was scanned before the loading and after the collapse. In this way, the comparison was able to be executed. The maximum vertical deformation was 115 mm. The DICM technique is a relatively new methodology in civil engineering; however, it has been applied for more than ten years in mechanical engineering. Therefore, the authors investigated the applicability of DICM in this field. As a result, the pre and the post-states were determined in 3D. The displacement of the ballast particles was able to be defined with the possibility of drawing the displacement trajectories of given points. The DICM can be a valuable methodology in railway engineering, e.g., laboratory tests and field test applications.
Open Access: Yes
INVESTIGATION OF THE GLUED INSULATED RAIL JOINTS APPLIED TO CWR TRACKS
Publication Name: Facta Universitatis Series Mechanical Engineering
Publication Date: 2021-01-01
Volume: 19
Issue: 4
Page Range: 681-704
Description:
This article summarizes the research results related to our own conducted extensive laboratory tests of polymer composite and steel fishplated glued insulated rail joints (GIRJs), namely axial tensile tests as well as vertical static and dynamic tests. The investigation dealt with the examination of GIRJs assembled with steel and special glass-fiber reinforced plastic (polymer composite) fishplates, both of them for CWR railway tracks (i.e. so-called gapless tracks or, in other words, railway tracks with continuously welded rails). The exact rail joint types were MTH-P and MTH-AP, consistently. The MTH P types have been commonly applied for many years in the CWR tracks in Europe, mainly in Hungary. The MTH-AP rail joints consist of fishplates that are produced by the APATECH factory (Russia). They are made of a fiberglass-amplified polymer composite material at high pressure and controlled temperature. This solution can eliminate electrical fishplate lock and early fatigue failures just as it can ensure adequate electrical insulation. The advantage of such rail joints can be that they are probably able to ensure the substitution of the glued insulated rail joints with relatively expensive steel fishplates currently applied by railway companies, e.g. Hungarian State Railways (MÁV). The aim of the mentioned research summarized in this paper is to formulate recommendations on technical applicability and on the technological instructions that are useful in everyday railway operation practice on the basis of the measurements and tests carried out on rail joints in laboratory.
Open Access: Yes
Investigation of glued insulated rail joints with special fiber-glass reinforced synthetic fishplates using in continuously welded tracks
Publication Name: Pollack Periodica
Publication Date: 2018-08-01
Volume: 13
Issue: 2
Page Range: 77-86
Description:
In this paper the authors partially summarize the results of a research on glued insulated rail joints with fiber-glass reinforced plastic fishplates (brand: Apatech) related to own executed laboratory tests. The goal of the research is to investigate the application of this new type of glued insulated rail joint where the fishplates are manufactured at high pressure, regulated temperature, glass-fiber reinforced polymer composite plastic material. The usage of this kind of glued insulated rail joints is able to eliminate the electric fishplate circuit and early fatigue deflection and it can ensure the isolation of rails' ends from each other by aspect of electric conductivity.
Open Access: Yes
