András Lajos Nagy

57201813409

Publications - 26

Development Process of TGDI SI Engine Combustion Simulation Model Using Ethanol–Gasoline Blends as Fuel

András Lajos Nagy Bence Zsoldos Máté Zöldy

Publication Name: Applied Sciences Switzerland

Publication Date: 2025-08-01

Volume: 15

Issue: 15

Page Range: Unknown

Description:

The Fit for 55 package introduced by the European Union aims to achieve a 55% reduction in greenhouse gas emissions by 2030. In parallel, increasingly stringent exhaust gas regulations have intensified research into alternative fuels. Ethanol presents a promising option due to its compatibility with gasoline, higher octane rating, and lower exhaust emissions compared to conventional gasoline. Additionally, ethanol can be derived from agricultural waste, further enhancing its sustainability. This study examines the impact of two ethanol–gasoline blends (E10, E20) on emissions and performance in a turbocharged gasoline direct injection (TGDI) spark-ignition (SI) engine. The investigation is conducted using three-dimensional computational fluid dynamics (3D CFD) simulations to minimize development time and costs. This paper details the model development process and presents the initial results. The boundary conditions for the simulations are derived from one-dimensional (1D) simulations, which have been validated against experimental data. Subsequently, the simulated performance and emissions results are compared with experimental measurements. The E10 simulations correlated well with experimental measurements, with the largest deviation in cylinder pressure being an RMSE of 1.42. In terms of emissions, HC was underpredicted, while CO was overpredicted compared to the experimental data. For E20, the IMEP was slightly higher at some operating points; however, the deviations were negligible. Regarding emissions, HC and CO emissions were higher with E20, whereas NOx and CO2 emissions were lower.

Open Access: Yes

DOI: 10.3390/app15158677

Morphological and dental wear pattern analysis of Upper Cretaceous theropod teeth from Central Europe

András Lajos Nagy Réka Kolláti Attila Ősi

Publication Name: Palaeobiodiversity and Palaeoenvironments

Publication Date: 2025-06-01

Volume: 105

Issue: 2

Page Range: 499-515

Description:

Theropod teeth have long been known from the Upper Cretaceous of Europe, but the 20 million years long interval spanning the Cenomanian to the Campanian has remained underrepresented in the fossil record and understudied. Recent discoveries from the Turonian and Coniacian of Austria and the Santonian of Hungary fill this gap to some extent. Here we report on a study of 2D morphometry and dental wear of Turonian–Maastrichtian theropod teeth from Central Europe aimed at shedding further light on the phyletic and adaptive diversity of Late Cretaceous theropods in the archipelago of Europe. Our results suggest that the taxa Paraves indet. and Paronychodon were present in the region from the Turonian to the Maastrichtian, while medium-sized tetanuran forms are known only until the early Campanian. The record of some groups, such as troodontid or bird-like forms, is more sporadic and known only from a few sites. Dental wear study indicates that theropod teeth rarely show severe wear exposing dentin, though spalled surfaces are commonly seen on tetanuran teeth. Dental microwear feature and texture analysis of the worn enamel surfaces show a dominance of scratches (82–100%), with somewhat higher complexity in some of the non-serrated forms. The largest tetanuran teeth differ in terms of scratch length, pit size and anizotropy from the small, serrated Paraves indet. 1 teeth, but overlap with those of the extant carnivore-scavenger Varanus komodoensis suggesting large tetanurans resembled V. komodoensis in feeding on large vertebrates.

Open Access: Yes

DOI: 10.1007/s12549-025-00657-2

Optimizing Parameter Sets for Laser-Textured Piston Rings Using Design of Experiments and Multibody Dynamics Calculations

András Lajos Nagy Gabor Laki Dominika Pintér László Boros

Publication Name: Coatings

Publication Date: 2025-05-01

Volume: 15

Issue: 5

Page Range: Unknown

Description:

Friction and wear reduction in internal combustion engines are crucial for improving efficiency and durability. This study investigates the effect of microtextured surfaces on friction power loss in an engine’s piston ring-cylinder system. A numerical analysis was conducted on piston rings equipped with dimple-shaped microtextures using AVL Excite Piston & Rings, modelling a hard chromium-coated piston ring and a cast iron cylinder. The goal was to determine the optimal surface texture parameters that minimize friction power loss under typical urban driving conditions with SAE 0W-30 oil. A two-step Design of Experiments (DoE) approach was employed, where the first step involved mapping the effects of texture parameters, i.e., dimple depth (A = 0.5, 1, 1.5 µm), dimple distance (B = 120, 160, 240 µm), and dimple diameter (C = 50, 60, 70 µm), to identify influential factors. The second step aimed at locating a parameter configuration with minimal friction power loss. The results demonstrated that the optimized texture parameters can significantly reduce friction power loss. The lowest friction power loss of 8.96 W was achieved with a dimple depth of 2 µm, distance of 80 µm, and diameter of 60 µm, which contributed to an 8.3% improvement over the reference surface. The model built to describe the investigated texturing approach exhibited a strong correlation with an R2 value of 0.93, and the deviation between predicted and measured values was below 1%. Future work will involve tribometer tests to experimentally validate the optimized parameters and confirm the simulation results.

Open Access: Yes

DOI: 10.3390/coatings15050528

Wear Scar Classification with Convolutional Neural Network

András Lajos Nagy Zsolt Tabakov

Publication Name: Lecture Notes in Networks and Systems

Publication Date: 2025-01-01

Volume: 1345 LNNS

Issue: Unknown

Page Range: 13-20

Description:

This article categorizes the wear features of ball-on-disc type specimens into two classes using a Tensorflow Convolutional Neural Network network. The convolutional neural network is employed for image classification, specifically in the field of tribology, involving surface analysis and wear characterization.

Open Access: Yes

DOI: 10.1007/978-3-031-87620-2_2

A Preliminary Study on Laser Surface Texturing of Passenger Car Engine Piston Rings

András Lajos Nagy Attila Schweighardt Gabor Laki Gergely Kovács

Publication Name: Fme Transactions

Publication Date: 2025-01-01

Volume: 53

Issue: 2

Page Range: 252-259

Description:

Laser surface texturing offers a possible solution for reducing friction between sliding surfaces in engineering applications. Optimized surface topography can also contribute to reduced wear and elevated longevity by modifying the load and speed-dependent friction state in a system. This preliminaryexperimental study investigates the applicability of affordable fibre laser marking systems for microtexturing piston rings, in order to achieve a measurable reduction in friction under subsystem model conditions. A selection of textures are applied to chromium-coated cast iron piston rings. The resulting surface topographies are characterized through confocal microscopy and subjected to friction testing. A correlation analysis is conducted on surface topography parameters to identify key laser process parameters. Findings indicate an improvement in the range of 7–8% in terms of friction coefficient with appropriate texture size.

Open Access: Yes

DOI: 10.5937/fme2502252L

Estimation of Thermodynamic and Emission Characteristics of a Sustainable Hydrogen-Gasoline Engine Through Simulation

András Lajos Nagy Péter Németh György Marton Barna Hanula

Publication Name: Lecture Notes in Networks and Systems

Publication Date: 2025-01-01

Volume: 1345 LNNS

Issue: Unknown

Page Range: 21-32

Description:

Hydrogen is expected to play a significant role in mobility and transportation as a form of energy source. To assess the effects of hydrogen as a gradual replacement fuel for internal combustion engines, a preliminary 1D thermodynamic simulation was carried out using AVL Boost for 0 vol%, 4 vol% and 8 vol% hydrogen content. Calculations were based on independently published research results, and focused on peak firing temperature (PFT), brake specific fuel consumption (BSFC), nitrous oxide emission (NOx), and carbon monoxide (CO) emission values. Results showed a decrease in BSFC of up to 3 g/kWh and ca. 5 mg/kWh decrease in CO emission with 8 vol% hydrogen, but also highlight an increase of PFT by 14 K, and ca. 0.5 g/kWh additional NOx production at high loads.

Open Access: Yes

DOI: 10.1007/978-3-031-87620-2_3

Complex dental wear analysis reveals dietary shift in Triassic placodonts (Sauropsida, Sauropterygia)

Torsten M. Scheyer Ingmar Werneburg Kinga Gere András Lajos Nagy Attila Ősi

Publication Name: Swiss Journal of Palaeontology

Publication Date: 2024-12-01

Volume: 143

Issue: 1

Page Range: Unknown

Description:

Placodonts were durophagous reptiles of the Triassic seas with robust skulls, jaws, and enlarged, flat, pebble-like teeth. During their evolution, they underwent gradual craniodental changes from the Early Anisian to the Rhaetian, such as a reduction in the number of teeth, an increase in the size of the posterior palatal teeth, an elongation of the premaxilla/rostrum, and a widening of the temporal region. These changes are presumably related to changes in dietary habits, which, we hypothesise, are due to changes in the type and quality of food they consumed. In the present study, the dental wear pattern of a total of nine European Middle to Late Triassic placodont species were investigated using 2D and 3D microwear analyses to demonstrate whether there could have been a dietary shift or grouping among the different species and, whether the possible changes could be correlated with environmental changes affecting their habitats. The 3D analysis shows overlap between species with high variance between values and there is no distinct separation. The 2D analysis has distinguished two main groups. The first is characterised by low number of wear features and high percentage of large pits. The other group have a high feature number, but low percentage of small pits. The 2D analysis showed a correlation between the wear data and the size of the enlarged posterior crushing teeth. Teeth with larger sizes showed less wear feature (with higher pit ratio) but larger individual features. In contrast, the dental wear facet of smaller crushing teeth shows more but smaller wear features (with higher scratch number). This observation may be related to the size of the food consumed, i.e., the wider the crown, the larger food it could crush, producing larger features. Comparison with marine mammals suggests that the dietary preference of Placochelys, Psephoderma and Paraplacodus was not exclusively hard, thick-shelled food. They may have had a more mixed diet, similar to that of modern sea otters. The diet of Henodus may have included plant food, similar to the modern herbivore marine mammals and lizards.

Open Access: Yes

DOI: 10.1186/s13358-024-00304-x

Trophic evolution in ornithopod dinosaurs revealed by dental wear

Gábor Botfalvai Imre Szenti Martin Segesdi András Lajos Nagy Lívia Vásárhelyi János Magyar Viviána Jó Zoltán Csiki-Sava Paul M. Barrett Attila Ősi

Publication Name: Nature Communications

Publication Date: 2024-12-01

Volume: 15

Issue: 1

Page Range: Unknown

Description:

Ornithopod dinosaurs evolved numerous craniodental innovations related to herbivory. Nonetheless, the relationship between occlusion, tooth wear rate, and tooth replacement rate has been neglected. Here, we reconstruct tooth wear rates by measuring tooth replacement rates and tooth wear volumes, and document their dental microwear. We demonstrate that total tooth volume and rates of tooth wear increased steadily during ornithopod evolution, with deeply-nested taxa wearing up to 3360 mm3 of tooth volume/day. Increased wear resulted in asymmetric tooth crown formation with uneven von Ebner line increment width by the Late Jurassic, and in faster tooth replacement rates in multiple lineages by the mid-Cretaceous. Microwear displays a contrasting pattern, with decreasing complexity and pit percentages in deeply-nested and later-occurring taxa. We hypothesize that early ornithopods were browsers and/or frugivores but deeply nested iguanodontians were bulk-feeders, eating tougher, less nutritious plants; these trends correlate with increasing body mass and longer gut passage times.

Open Access: Yes

DOI: 10.1038/s41467-024-51697-9

Optimizing Experimental Design to Determine Friction and Wear Characteristics of Used Oil Contaminated with E20 Fuel †

András Lajos Nagy Dominika Pintér

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

The aim of this paper is to develop an experiment design to determine the wear and friction parameters of an SAE 0W20-grade reference oil and an SAE 0W20-grade used oil contaminated with E20 fuel. Wear tests in a ball–disc arrangement were conducted at temperatures and loads established using Design of Experiments. A surface analysis of the wear scars was performed using a digital microscope, while the oils were investigated using a viscometer and a Fourier-transform infrared spectrometer. Design of Experiments was further employed to develop two models using R software. For the reference oil, the developed model was only suitable for screening, while the model for the E20 fuel contaminated used oil showed a 9.8% difference between the measured and estimated coefficients of friction.

Open Access: Yes

DOI: 10.3390/engproc2024079057

Topography Pre-Treatment of Laser-Textured Surfaces for Friction Simulation in AVL Excite †

András Lajos Nagy Gabor Laki László Boros

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

This study presents the challenges arising during the numerical design and simulation of surface-microtextured piston rings. The evaluation of performance is based on the values of asperity and hydrodynamic friction, as well as the lubricant film thickness. The simulation tool AVL Excite Piston & Rings is used to perform the calculations. The aim of this study is to understand how selected surface pre-processing (pre-treatment) steps affect the calculations. Two methods are presented to achieve a realistic surface topography representative of a state after running-in. Pre-treatment is performed through metrological filtering and thresholding of the topography, and Gaussian smoothing of the virtually applied micro-texture array is carried out. The results show the anticipated behavior of decreasing asperity and hydrodynamic friction losses with the concurrent application of both techniques.

Open Access: Yes

DOI: 10.3390/engproc2024079095

Oil Degradation Patterns in Diesel and Petrol Engines Observed in the Field—An Approach Applying Mass Spectrometry

Charlotte Besser Péter Raffai Marcella Frauscher András Lajos Nagy Adam Agocs Andjelka Ristic Zsolt Tabakov

Publication Name: Lubricants

Publication Date: 2023-09-01

Volume: 11

Issue: 9

Page Range: Unknown

Description:

Engine oil degradation and tribological properties are strongly interrelated. Hence, understanding the chemical processes resulting in additive depletion and degradation products is necessary. In this study, in-service engine oils from petrol and diesel vehicles were analyzed with conventional and advanced methods (mass spectrometry). Additionally, the effect of the utilization profile (short- vs. long-range) was studied. Petrol engine oils generally showed accelerated antioxidant and antiwear degradation and higher oxidation, especially in the case of a short-range utilization profile, which can be attributed to the higher air-to-fuel ratio (more rich combustion) compared to diesel engines. A detailed overview of oxidation and nitration products, as well as degradation products resulting from zinc dialkyl dithiophosphate and boron ester antiwear additives, diphenylamine antioxidants and salicylate detergents is given. A side reaction between oxidation products (aromatic carboxylic acids) and the boron ester antiwear is highlighted. This reaction was only detected in the petrol engine oils, where the oxidation products were measured in a high abundance. However, no side reaction was found in the samples from the diesel vehicles, since there the aromatic carboxylic acids were largely absent due to lower oxidation.

Open Access: Yes

DOI: 10.3390/lubricants11090404

Smart Hybrid Energy Management System in a Passenger Car

András Lajos Nagy Péter Németh Barna Hanula

Publication Name: Chemical Engineering Transactions

Publication Date: 2023-01-01

Volume: 107

Issue: Unknown

Page Range: 457-462

Description:

The technological advancements of internal combustion engines, batteries, and electric propulsion technology have reached such a level that they bring a new dimension to the potential of hybrid propulsion systems. Partially or fully electric vehicle propulsion drivetrains receive significant attention when considering the future of mobility, as they have the potential to reduce the sector's greenhouse gas emissions and dependence on fossil fuels and hopefully mitigate climate change. This paper aims to design a hybrid powertrain for a conventional passenger vehicle that can cover the performance requirements of everyday average urban usage with electric propulsion to reduce consumption and emissions and improve sustainability. It aims to present the performance requirements of the vehicle based on road measurements conducted under various traffic conditions and usage environments. The energy savings achieved through the auxiliary powertrain will also be evaluated based on real-life, everyday usage conditions. Finally, the paper introduces a Life Cycle Assessment (LCA), which compares the original conventional propulsion system with the new hybrid powertrain.

Open Access: Yes

DOI: 10.3303/CET23107077

Investigation of Turbocharger Compressor Wheel Damage Due to Collision with Condensed Water Droplets

I. Zsoldos András Lajos Nagy Richárd Takács

Publication Name: Lecture Notes in Mechanical Engineering

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 575-581

Description:

The compressor wheels used in turbochargers have typically been made of aluminium alloy for decades. The primary reason is to achieve the lowest possible rotor inertia. However, while in the past this component was only encountered with filtered air, nowadays, due to developments in compliance with tightening emission standards, various fluids also collide with the spinning blades, which can cause mechanical damage. One such fluid is condensed water in the low-pressure exhaust gas channel (LP-EGR) formulated at cold starts and low-load conditions. This kind of design has been developed to reduce the nitrogen oxide emission and is used in both Otto and Diesel engines. This paper presents a testing method - implemented on a component testbench - and its results for this phenomenon. First, the effect of the volume flow of the condensed water colliding with the spinning blades was analyzed, and then, in addition to a constant volume flow, the speed dependence of the degree of damage was also determined. Next to the visual inspections, the physical changes on the blades were also detected by vibration diagnostic tools, mainly by analyzing the amplitude of the order correlated to the number of blades, from which we can deduce the changed balance level of the rotor.

Open Access: Yes

DOI: 10.1007/978-3-031-15211-5_48

Multi-proxy dentition analyses reveal niche partitioning between sympatric herbivorous dinosaurs

Alistair R. Evans Imre Szenti Martin Segesdi Kinga Gere András Lajos Nagy János Magyar Viviána Jó Ákos Kukovecz Paul M. Barrett Attila Ősi

Publication Name: Scientific Reports

Publication Date: 2022-12-01

Volume: 12

Issue: 1

Page Range: Unknown

Description:

Dentitions of the sympatric herbivorous dinosaurs Hungarosaurus (Ankylosauria, Nodosauridae) and Mochlodon (Ornithopoda, Rhabdodontidae) (Santonian, Hungary) were analysed to investigate their dietary ecology, using several complementary methods—orientation patch count, tooth replacement rate, macrowear, tooth wear rate, traditional microwear, and dental microwear texture analysis (DMTA). Tooth formation time is similar in Hungarosaurus and Mochlodon, and traditional and DMTA microwear features suggest low-browsing habits for both taxa, consistent with their inferred stances and body sizes. However, Mochlodon possesses a novel adaptation for increasing dental durability: the dentine on the working side of the crown is double the thickness of that on the balancing side. Moreover, crown morphology, enamel thickness, macrowear orientation, and wear rate differ greatly between the two taxa. Consequently, these sympatric herbivores probably exploited plants of different toughness, implying dietary selectivity and niche partitioning. Hungarosaurus is inferred to have eaten softer vegetation, whereas Mochlodon likely fed on tougher material. Compared to the much heavier, quadrupedal Hungarosaurus, the bipedal Mochlodon wore down more than twice as much of its crown volume during the functional life of the tooth. This heavy tooth wear might correlate with more intensive food processing and, in turn, could reflect differences in the metabolic requirements of these animals.

Open Access: Yes

DOI: 10.1038/s41598-022-24816-z

Wear behaviour of ceramic particle reinforced atmospheric plasma spray coatings on the cylinder running surface of internal combustion engines

I. Zsoldos Alexander Dudas András Lajos Nagy Gabor Laki Barna Hanula Dirk Bartel

Publication Name: Wear

Publication Date: 2022-08-15

Volume: 502-503

Issue: Unknown

Page Range: Unknown

Description:

Atmospheric plasma spray coatings can provide a solution for corrosion and wear resistant cylinder coating surfaces in hybrid powertrains. This article presents experimental results from a model study of metal matrix composite coating samples of chromium steel with varied ceramic content, in order to characterize the effect of hard particles and porous coating structure on friction and wear. Experiments were conducted on a high-frequency reciprocating rig with coated cast-iron cylinder segments and hard chromium coated piston ring segments. Samples were investigated under continuous and scarce lubrication conditions. A ceramic content of 35 wt% was found to be ideal in terms of friction and wear. Coatings with a higher ceramic content exhibited severe abrasive wear, whereas a ceramic content under 35 wt% allowed for increased adhesion between the ring and cylinder surfaces. A detailed investigation of focused ion beam milled sections of the coated cylinder wall segments revealed a stabilizing effect of the ceramic particles, which reduces the delamination of the coating structure.

Open Access: Yes

DOI: 10.1016/j.wear.2022.204373

A Review on Friction Reduction by Laser Textured Surfaces in Internal Combustion Engines

András Lajos Nagy Jan Rohde-Brandenburger Gabor Laki Barna Hanula

Publication Name: Tribology Online

Publication Date: 2022-01-01

Volume: 17

Issue: 4

Page Range: 318-334

Description:

The internal combustion engine will be required as a bridge-technology in the upcoming decades to achieve a significant reduction in local emissions in the mobility, and logistics sector. Alternative fuel technologies will present new mechanical engineering challenges, including increasing efficiency and reducing mechanical losses. Textured surfaces with appropriate manufacturing parameters can enhance lubrication, and reduce friction in sliding and rolling contacts, e.g., journal bearings, or the piston ring – cylinder subsystem. This paper gives an overview of 80 scientific works related to laser surface technologies, with an emphasis on surface texturing for friction reduction from the viewpoint of engine development. The most common texture types, further directions, and general challenges are highlighted in the summary.

Open Access: Yes

DOI: 10.2474/trol.17.318

Rapid fleet condition analysis through correlating basic vehicle tracking data with engine oil ft-ir spectra

Charlotte Besser Péter Raffai András Lajos Nagy Bettina Ronai Adam Agocs Jan Rohde-Brandenburger Nicole Dörr

Publication Name: Lubricants

Publication Date: 2021-12-01

Volume: 9

Issue: 12

Page Range: Unknown

Description:

Engine oil condition and tribological performance are strongly interrelated. Accordingly, oil condition monitoring is common in various applications. This is especially important, as oil condition depends on the fueling and utilization profile of an internal combustion engine. Common practice involves the measurement of various parameters, such as the total acid number and total base number, oxidation, nitration, viscosity, and elemental composition; thus, it can be time-consuming and resource-intensive. This study provides a methodology for rapid analysis for large vehicle fleets or sample sizes, using only Fourier-transformed infrared spectroscopy and the subsequent multivariate data analysis offers a rapid alternative to commonly available methods. The described method provides a rapid, cost-efficient, and intuitive approach to uncovering differences in the oil condition. Furthermore, understanding the underlying reasons in engine construction and the resulting chemical degradation is also possible.

Open Access: Yes

DOI: 10.3390/lubricants9120114

Comprehensive assessment of oil degradation patterns in petrol and diesel engines observed in a field test with passenger cars – Conventional oil analysis and fuel dilution

Charlotte Besser András Lajos Nagy Adam Agocs Jan Rohde-Brandenburger József Perger Michael Schandl Zsolt Tabakov Nicole Dörr

Publication Name: Tribology International

Publication Date: 2021-09-01

Volume: 161

Issue: Unknown

Page Range: Unknown

Description:

Requirements for modern internal combustion engines are lower emissions, higher power density and longer maintenance intervals. These trends increase the demands on engine components, including lubricants. In a field study of petrol and diesel vehicles, oil condition of 47 engine oils from 12 vehicles are correlated with fresh oil properties and operating conditions, i.e., trip length and speed. Long-range petrol vehicles displayed accelerated chemical oil degradation compared to diesel vehicles. An explanation for this behaviour is assumed to be the difference air-to-fuel ratio. Short-range petrol vehicles showed an even faster oil degradation and significant changes in oil viscosity due to fuel dilution. Diesel vehicles exhibited higher soot loading and more pronounced engine wear indicated by iron content in the oils.

Open Access: Yes

DOI: 10.1016/j.triboint.2021.107079

Artificial aging experiments of neat and contaminated engine oil samples

I. Zsoldos András Lajos Nagy Jan Rohde-Brandenburger

Publication Name: Lubricants

Publication Date: 2021-06-01

Volume: 9

Issue: 6

Page Range: Unknown

Description:

This study highlights how the results from an artificial engine oil aging method compare to used engine oil samples collected from a vehicle fleet. Additionally, this paper presents the effect of contaminating the oil during aging with synthetic fuel alternatives on the physical and chemical properties of artificially aged engine oil samples. A laboratory-scale artificial thermo-oxidative aging experiment was conducted on multiple samples of commercially available formulated fully-synthetic SAE 0W-30 engine oil. The goal of the experiment was to establish the validity of the artificially aged samples as well as the validity of the underlying process in reproducibly fabricating small batches of aged engine oil with comparable chemical and physical properties to real-life used oils. Eight samples were subjected to distinct load cases (temperature, air flow rate, sample volume and aging time). Six additional samples were subjected to an intermediate load case, with five of them contaminated with selected conventional fuels and novel automotive fuel candidates. Conventional oil analysis was conducted on each sample to determine oxidation, residual additive content, kinematic viscosity and total base number. Additionally, analysis results were compared to in-use engine oil samples through PCA. The resulting oil condition after aging is in accordance with independently published results in terms of zinc dialkyldithiophosphate content and kinematic viscosity. Contaminated aging with OME3-5 resulted in a drop in antioxidant content and elevated kinematic viscosity. Based on the comparison with in-use samples, artificial aging of 200 mL engine oil at 180◦ C with 1 L/min air flow for 96 h can produce similar oil conditions as mixed vehicle use for 7000 km.

Open Access: Yes

DOI: 10.3390/lubricants9060063

Artificial Aging of Ultra-low Viscosity Lubricant Samples on a Programmable Oil Aging Rig

I. Zsoldos András Lajos Nagy

Publication Name: Lecture Notes in Mechanical Engineering

Publication Date: 2021-01-01

Volume: 22

Issue: Unknown

Page Range: 139-147

Description:

An artificial lubricant aging rig was developed in order to simulate aging processes of automotive lubricants. This article presents the development of the aging apparatus and its control system as well as results of artificial aging of SAE 0W-20 grade automotive lubricant with a modified thermal cycling procedure. Friction and wear measurements on a high frequency reciprocating rig were conducted to describe the lubricating properties of the artificially aged samples. Select oil samples were analyzed through FTIR spectroscopy.

Open Access: Yes

DOI: 10.1007/978-981-15-9529-5_12

A friction and wear study of laboratory aged engine oil in the presence of diesel fuel and oxymethylene ether

I. Zsoldos András Lajos Nagy Jan Knaup

Publication Name: Tribology Materials Surfaces and Interfaces

Publication Date: 2019-01-02

Volume: 13

Issue: 1

Page Range: 20-30

Description:

Non-fossil fuels for the commercial and passenger vehicle sector are gaining more importance due to their positive effects on exhaust gas emissions. Ongoing research investigating a broad variety of biofuels, synthetic fuels and regenerative fuels shows that a reduction of CO 2 emissions can be possible without major modifications to the existing vehicle infrastructure. An internal combustion engine is a complex system of physical and chemical mechanisms, all of which contribute to the performance output, exhaust gas composition, durability and longevity of the engine. Modifying the fuel will not only result in differing chemical reactions and thermodynamic efficiency but will also affect friction and wear through the dilution and degradation of the lubricant. This study aims to investigate the variation of friction and wear in a model system due to the introduction of oxymethylene ether and regular diesel fuel to the lubricant. High-frequency reciprocating rig experiments will be carried out on 100Cr6 steel specimen with laboratory aged fully formulated commercially available SAE 0W-20 grade engine oil containing defined amounts of OME 3−5 and regular diesel fuel. The surface of the steel specimen will be analysed using optical microscopy and scanning electron microscopy.

Open Access: Yes

DOI: 10.1080/17515831.2018.1558026

Effect of locally increased melted layer thickness on the mechanical properties of laser sintered tool steel parts

I. Fekete T. Ibriksz István Hatos András Lajos Nagy B. Kocsis H. Hargitai

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2018-10-18

Volume: 426

Issue: 1

Page Range: Unknown

Description:

Additive technologies have several advantages over conventional manufacturing, such as the freedom of geometry of the products and internal structures. There are also some limitations and problems, deriving from stopping the process during the production. By restarting the process, the building often continues with a thicker starting layer due to the deposition of two or more layers. The effect of skipped melting of layers is investigated in this paper. Maraging steel powder (MS1) was used in direct metal laser sintering (DMLS) process to produce samples with increased thickness of melted layers. The layer thickness was increased in 20 μm steps up to 160 μm with 0.5 mm offset between the increased thickness layers. Porosity caused by the uneven melting was measured by optical microscope, mechanical tests were carried out to quantify the effect of skipped layers and fractured surfaces were observed under SEM. We have found that the yield strength and tensile strength are not affected if the layer thickness is slightly increased locally in the laser sintered part, while even a small increase in porosity greatly reduces the total elongation of the specimen. The decrease of impact energy due to the porosities shows similar correlation with the decrease of percentage elongation at break. However, the Charpy impact test is much more sensitive to layer skipping, the lack of melted layers lowers the impact strength significantly.

Open Access: Yes

DOI: 10.1088/1757-899X/426/1/012014

A review on the effect of alternative fuels on the friction and wear of internal combustion engines

I. Zsoldos András Lajos Nagy Jan Knaup

Publication Name: Lecture Notes in Mechanical Engineering

Publication Date: 2018-01-01

Volume: 0

Issue: 9783319756769

Page Range: 42-55

Description:

The climate policy of the EU specifies strict limits for harmful exhaust gases of passenger cars and commercial vehicles. Electric Mobility plays a significant role in reaching the fleet targets, but internal combustion engines (ICEs) will still be necessary in the next 30 years in medium to long distance transportation. Within the scope of this review article, research activities concerning engine performance, exhaust emissions, friction, wear and corrosion of components in relation to drop-in fuel alternatives, as well as the impact of such fuels on the degradation of the lubricant will be presented. Production pathways and properties of alternative fuels will be briefly introduced.

Open Access: Yes

DOI: 10.1007/978-3-319-75677-6_4

Friction and Wear of the Piston Ring - Cylinder Liner System with Artificially Aged Ultra-low Viscosity Engine Oils

András Lajos Nagy

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2024-01-01

Volume: 52

Issue: 2

Page Range: 190-198

Description:

This study aims to investigate the performance of artificially aged prototype engine oils through friction and wear experiments. Experiments were performed on a piston ring - cylinder liner model system with boundary conditions derived from real-life operating conditions. The experimental design implemented two prototype oils (SAE 0W-12 and 0W-16) in unaltered and artificially aged form. An additional fully formulated off-the-shelf engine oil (SAE 0W-20) was also aged and analyzed as reference. Oil samples were artificially aged in a custom rig, to simulate long-term in-engine use through thermal cycling at 180 °C. Fourier Transformed Infrared Spectroscopy of the lubricant samples highlighted a depletion of zinc dialkyl-ditiophosphate antiwear additives in all cases, which is comparable to a selected in-service oil. Oxidation was also measurable, albeit lower compared to the in-service sample. Averaged friction coefficients showed a ranking of aged 0W-12 < aged 0W-16 < unaltered 0W-12 < unaltered 0W-16. A decrease in surface roughness was experienced with aged oil samples, whereas unaltered 0W-16 oil produced an unexpected transition in the wear phenomenon and resulted in severe wear.

Open Access: Yes

DOI: 10.3311/PPtr.22918

Processing FT-IR data for facilitated oil condition monitoring

András Lajos Nagy Adam Agocs Zsolt Tabakov

Publication Name: 2022 IEEE 1st International Conference on Cognitive Mobility Cogmob 2022

Publication Date: 2022-01-01

Volume: Unknown

Issue: Unknown

Page Range: 47-50

Description:

The physical and chemical condition of a lubricant plays a vital role in the long-term operability of engineering systems. Hence, oil condition monitoring of high-value and heavy-duty equipment is a common practice across numerous industries. However, this practice is not utilized on a regular basis for passenger cars, and car fleets. For general automotive purposes, a simpler time and mileage-based approach is favored. This approach employs fixed oil change intervals, that are based on average usage, with more recently produced vehicles only slightly modifying these intervals by monitoring oil temperatures over time. With rising environmental concerns and increasing focus on systemic approaches, reducing waste production is gaining importance. Being aware of lubricant condition opens up the opportunity to optimized, condition-based oil changes, that can help reduce waste by elongating the service life of engine oils. This study presents a methodology of processing FT-IR data that allows for a simplified decision making regarding the prolonged applicability of used engine oil. The presented method can be implemented as a step of planned maintenance during scheduled service at a repair shop, as well as a regular investigation by fleet operators.

Open Access: Yes

DOI: 10.1109/CogMob55547.2022.10117798

Optimizing the Artificial Aging Process of Lubricating Oils Contaminated by Alternative Fuel Using Design of Experiments Methodology

András Lajos Nagy Dominika Pintér

Publication Name: Lubricants

Publication Date: 2025-09-01

Volume: 13

Issue: 9

Page Range: Unknown

Description:

This study aimed to develop an experimental method for producing artificially aged oil with properties—such as coefficient of friction, average wear scar diameter, and antiwear additive content—similar to those of used oil contaminated with alternative fuel, sampled after 129 h of engine test bench operation. A design of experiment (DoE) methodology was applied to examine the effects of various parameters and identify optimal settings. Friction and wear tests were conducted using an Optimol SRV5 tribometer in a ball-on-disc configuration, while wear scars were analyzed with a Keyence VHX-1000 digital microscope. Oil analysis was conducted with an Anton Paar 3001 viscometer and a Bruker Invenio-S Fourier-transform infrared spectrometer. The DoE results showed that the heating duration had a negligible effect on oil degradation. Aging time primarily affected changes in the friction coefficient and average wear scar diameter, whereas aging temperature was the primary factor influencing the anti-wear additive content. Gaussian elimination identified the optimal aging parameters as 132.8 °C and 103.1 h. These results were confirmed through surface analysis using a ThermoFisher NexsaG2 X-ray photoelectron spectrometer, which showed that the tribofilm composition of the used oil most closely matched that of artificially aged oils prepared at 120 °C for 96 h and 140 °C for 120 h. The strong correlation between the predicted and experimentally confirmed conditions demonstrates the reliability of the proposed method for replicating realistic aging effects in lubricating oils.

Open Access: Yes

DOI: 10.3390/lubricants13090405