Papers by Eduardo Tomanik
Tribology International, 2016
Metalurgia & materiais, 2004
ABM Proceedings, Jul 31, 2009
Resumo O objetivo principal deste trabalho é o desenvolvimento de um programa computacional que s... more Resumo O objetivo principal deste trabalho é o desenvolvimento de um programa computacional que simule os principais testes tribológicos, tais como: reciproco, pino sobre disco e block on ring. Desta forma, deseja-se obter uma espécie de Laboratório Tribológico Virtual, a partir do qual se podem prever as principais tendências relacionadas ao atrito, desgaste e lubrificação para sistemas compostos de perfis com geometrias diversas. Os dados calculados pelo modelo foram comparados com resultados experimentais de um teste reciprocativo de um anel de pistão contra duas superfícies de cilindro a diferentes velocidades, de modo a reproduzir diferentes regimes de lubrificação.
Lubricants
The growing awareness of reduced friction losses and new demands for electrical powertrains deman... more The growing awareness of reduced friction losses and new demands for electrical powertrains demand improved lubricants. Due to their unique properties, such as high thermal and electrical conductivity, graphene and its derivatives have been investigated for tribological applications, especially as lubricant additives. In this work, we investigated three commercially available graphene variants, one comprising a few layers and the other two comprising nanoplates, after functionalization as additives to lithium soap grease. The grease temperature dropping point increased by approximately 6 °C. Additionally, during the reciprocating friction test, friction increased with the test duration for the baseline grease, whereas it decreased for the ones containing graphene-based additives. On the test end, friction was reduced by 8% compared to the baseline grease. On a four-ball tribometer, the wear scar was reduced from 10 to 18% compared to the baseline grease. In general, no significant d...
SAE technical paper series, Sep 21, 2021
SAE technical paper series, Feb 4, 2022
Surface topography, Aug 8, 2018
The piston system accounts for about the half of the frictional losses of internal combustion eng... more The piston system accounts for about the half of the frictional losses of internal combustion engines and requires special testing methods to understand and improve its function. The most common wa ...
SAE technical paper series, Feb 4, 2022
Tribology International, Aug 1, 2016
It is of a vital importance to reduce the frictional losses in the engines and hence the fuel/ene... more It is of a vital importance to reduce the frictional losses in the engines and hence the fuel/energy consumption. The major contributors to this are the oil control ring and cylinder liner interactions difficult to understand when comparing the experimental and theoretical results. The latter largely depend on the liner surface measurement and filtering type used in the simulations. Therefore, low-pass and high-pass filtrations were applied and the friction behaviors between the filtered liner surfaces and a perfectly flat ring surface were simulated for different engine speeds. The surfaces low-pass filtered by lower cutoffs showed higher friction, while the type of de-noising revealed about two and a half times higher friction. Stylus surfaces showed larger friction than the interference ones.
Vehicles
Transient car emission tests generate huge amount of test data, but their results are usually eva... more Transient car emission tests generate huge amount of test data, but their results are usually evaluated only using their “accumulated” cycle values according to the homologation limits. In this work, two machine learning models were developed and applied to a truck RDE test and two light-duty vehicle chassis emission tests. Different from the conventional approach, the engine parameters and fuel consumption were acquired from the Engine Control Unit, not from the test measurement equipment. Instantaneous engine values were used as input in machine-learning-based digital twins. This novel approach allows for much less costly vehicle tests and optimizations. The paper’s novel approach and developed digital twins model were able to predict both instantaneous and accumulated fuel consumption with good accuracy, and also for tests cycles different to the one used to train the model.
Lubricants
The tribological performance of a thermal sprayed, mirror-like surface with localized protuberanc... more The tribological performance of a thermal sprayed, mirror-like surface with localized protuberances was investigated through tribotests and computational simulation. A composite coating with a 410L steel matrix and M2 tool steel hard particles was applied by the cold spray process as a bore coating for combustion engines. The presence of protuberances promoted the quick formation of an antifriction tribofilm when tested with an SAE 0W-16 containing ZDDP and MoDTC, which significantly reduced the asperity friction in comparison to the conventional engine coated bores in reciprocating tribological tests. An in-house computational model using deterministic numerical methods was used for the mixed and hydrodynamic lubrication regime. Lubricant film thickness and friction were simulated for a piston ring versus the proposed coating. The computer simulations showed that the protuberances reduced the hydrodynamic friction by increasing the otherwise very thin oil film thickness of mirror-l...
SAE technical paper series, Aug 30, 2022
Tribology and Interface Engineering Series, 2002
Eng
Graphene-based materials have great potential for tribological applications. Graphene’s unique pr... more Graphene-based materials have great potential for tribological applications. Graphene’s unique properties such as low shear resistance, high stiffness, and thermal conductivity make it an attractive material for improving the properties of lubricants in a wide range of industrial applications, from vehicles to house refrigerators and industrial machinery such as gearboxes, large compressors, etc. The current review aims to give an engineering perspective, attributing more importance to commercially available graphene and fully formulated lubricants instead of laboratory-scaled produced graphene and base oils without additives. The use of lubricants with graphene-based additives has produced e.g., an increase in mechanical efficiency, consequently reducing energy consumption and CO2 emissions by up to 20% for domestic refrigerators and up to 6% for ICE vehicles. Potential effects, other than purely friction reduction, contributing to such benefits are also briefly covered and discussed.
SAE Technical Paper Series, 2022
It is of a vital importance for automotive industry to reduce the frictional losses in internal c... more It is of a vital importance for automotive industry to reduce the frictional losses in internal combustion engines and hence their fuel consumption and CO2 emissions. The major contributors to this are the oil control ring (OCR) and cylinder liner interactions. These interactions are of complex multi-physics and multi-scale nature and many attempts have been made to improve the modelling and understanding of the phenomena involved. Even though continuous improvements have been made (see for ex. [1-3]), the form, waviness and roughness variation of real engineering surfaces still cause a large scatter in the results. The most of the models include measured liner surfaces, which are then filtered to capture the micro-effects of the roughness scale. However, by doing this, the contact conditions change (asperity contact distributes more evenly, see Fig. 1) such that the part of the boundary friction reduces and the part of the hydrodynamic friction increases accordingly for a given eng...
SAE Technical Paper Series, 2021
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Papers by Eduardo Tomanik