doc. Ing. Petr Svoboda, Ph.D.
E-mail:   Petr.Svoboda@vut.cz  WWW:   https://scholar.google.cz/citations?user=jXBWSiAAAAAJ&hl=cs Dept.:   Institute of Machine and Industrial Design Dept. of Tribology Position:   Associate Professor Room:   A3/605

Supervised courses:

• CAD (3CD)
• CAD (3CD-A)
• CAD (3CD-K)
• Engineering Drawing Fundamentals (1K)
• Engineering Drawing Fundamentals (1K-K)
• Engineering Drawing Fundamentals (1K-A)
• Mechanical Design Project (ZIP)
• Research Project and Its Management (9VPR)

Publications:

• VENCL, A., BOBIC, I., BOBIC, B., JAKIMOVSKA, K., SVOBODA, P., KANDEVA, M.:
  Erosive wear properties of ZA-27 alloy-based nanocomposites: Influence of type, amount and size of nanoparticle reinforcements, Tsinghua University Press
  journal article in Web of Science
• MICHALEC, M.; SVOBODA, P.; KŘUPKA, I.; HARTL, M.:
  Tribological behaviour of smart fluids influenced by magnetic and electric field – A review
  journal article in Scopus
• VENCL, A.; BOBIC, B.; VUCETIC, F.; SVOBODA, P.; POPOVIC, V.; BOBIC, I.:
  Effect of Al2O3 nanoparticles and strontium addition on structural, mechanical and tribological properties of Zn25Al3Si alloy, Springer Berlin Heidelberg
  journal article in Web of Science
• KANDEVA, M.; ZADOROZHNAYA, E.; KALITCHIN, ZH.; SVOBODA, P.:
  Tribological studies of high velocity oxy-fuel (HVOF) superalloy coatings,
  Journal of the Balkan Tribological Association, Vol.24, (2018), No.3, pp.411-428, ISSN 1310-4772, Scibulcom Ltd.
  journal article - other
• M. KANDEVA, V. BALABANOV, E. ZADOROZHNAYA, ZH. KALITCHIN, P. SVOBODA, I. LEVANOV.:
  Environmental Protection by Self-organisation of Tribosystems with Self-lubricating Materials in Dry Friction. Part II: Iinvestigations at Different Dry Sliding Rates , SCIBULCOM LTD
  journal article in Web of Science
• M. KANDEVA, V. BALABANOV, E. ZADOROZHNAYA, ZH. KALITCHIN, P. SVOBODA:
  Environmental Protection by Self-organisation of Tribosystems with Self-lubricating Materials in Dry Friction. Part I. Investigations at Different Loads, SCIBULCOM LTD
  journal article in Web of Science
• KANDEVA, M. KARASTOYANOV, D., NIKOLCHEVA, G. STOJANOVIĆ, B., SVOBODA, P., VENCL, A.:
  Tribological studies on copper-based friction linings, Faculty of Engineering, University of Kragujevac, Serbia
  journal article in Scopus
• KANDEVA, M. KARASTOYANOV, D., NIKOLCHEVA, G. STOJANOVIĆ, B., SVOBODA, P., VENCL, A.:
  Tribological studies on copper-based friction linings,
  15th International Conference on Tribology, SERBIATRIB ‘17, pp.51-60, ISBN 978-86-6335-041-0, (2017)
  conference paper
  akce: 15th International Conference on Tribology – SERBIATRIB ‘17, Kragujevac, 17.05.2017-19.05.2017
• KOŠŤÁL, D.; ŠPERKA, P.; SVOBODA, P.; KŘUPKA, I.; HARTL, M.:
  Influence of lubricant inlet film thickness on EHL contact starvation
  journal article in Web of Science
• SVOBODA, P.; KOŠŤÁL, D.; GALAS, R.; KŘUPKA, I.; HARTL, M.:
  Tribological behaviour of ultra dispersed diamond-graphite in liquid lubricants, Scibulcom
  journal article in Scopus
• DONG, J.; SVOBODA, P.; VRBKA, M.; KOŠŤÁL, D.; URBAN, F.; ČÍŽEK, J.; ROUPCOVÁ, P.; DONG, H.; KŘUPKA, I.; HARTL, M.:
  Towards near-permanent CoCrMo prosthesis surface by combining micro-texturing and low temperature plasma carburising, Elsevier B.V.
  journal article in Web of Science
• SVOBODA, P.; KOŠŤÁL, D.; KŘUPKA, I.; HARTL, M.:
  Study of Scale Effect in a Starved Elastohydrodynamically Lubricated Contact,
  Applied Mechanics and Materials, Vol.821, (2016), No.1, pp.138-143, ISSN 1662-7482, Trans Tech Publications
  journal article - other
• SVOBODA, P.; KOŠŤÁL, D.; KŘUPKA, I.; HARTL, M.:
  Experimental Investigation of Lubrication Film Formation at Start-up of Smooth Surfaces, MM Publishing s r. o.
  journal article in Scopus
• KOŠŤÁL, D.; ŠPERKA, P.; SVOBODA, P.; KŘUPKA, I.; HARTL, M.:
  Experimental observation of elastohydrodynamically lubricated contacts replenishment
  journal article in Scopus
• SVOBODA, P.; KOŠŤÁL, D.; KUŇÁK, J.; KŘUPKA, I.:
  Study of grease behaviour in a starved Elastohydrodynamically lubricated contact,
  MM Science Journal, Vol.2014, (2014), No.June, pp.464-469, ISSN 1805-0476, MM Science Journal
  journal article - other
• SVOBODA, P.; KOŠŤÁL, D.; KŘUPKA, I.; HARTL, M.:
  Experimental study of starved EHL contacts based on thickness of oil layer in the contact inlet,
  Tribology International, Vol.67, (2013), No.1, pp.140-145, ISSN 0301-679X, ELSEVIER
  journal article - other
• SVOBODA, P.; VRBKA, M.; ŠPERKA, P.; KŘUPKA, I.; HARTL, M.:
  Study of Lubrication Film Formation in Ball Bearings Under Starved Conditions,
  ASME/STLE 2011 International Joint Tribology Conference, pp.183-185, ISBN 978-0-7918-5474-7, (2011), American Society of Mechanical Engineers, Tribology Division, TRIB
  conference paper
  akce: ASME/STLE 2011 International Joint Tribology Conference, Los Angeles, 2011, Los Angeles, CA, 24.10.2011-26.10.2011
• VRBKA, M.; KŘUPKA, I.; SVOBODA, P.; ŠPERKA, P.; NÁVRAT, T.; HARTL, M.; NOHAVA, J.:
  Effect of shot peening on rolling contact fatigue and lubricant film thickness within mixed lubricated non-conformal rolling/sliding contacts,
  Tribology International, Vol.44, (2011), No.12, pp.1726-1735, ISSN 0301-679X, Elsevier
  journal article - other
• KŘUPKA, I.; HARTL, M.; BAIR, S.; SVOBODA, P. ;KUMAR, P.:
  Mechanical Degradation of the Liquid in an Operating EHL Contact,
  Tribology Letters, Vol.40, (2010), No.3, pp.1-7, ISSN 1023-8883, Springer
  journal article - other

List of publications at Portal BUT

Abstracts of most important papers:

• SVOBODA, P.; KOŠŤÁL, D.; KŘUPKA, I.; HARTL, M.:
  Experimental study of starved EHL contacts based on thickness of oil layer in the contact inlet,
  Tribology International, Vol.67, (2013), No.1, pp.140-145, ISSN 0301-679X, ELSEVIER
  journal article - other
  This paper describes the experimental approach based on the thickness of the oil layer entering the starved contact. Through the comparison with the theoretical prediction it was found that acceptable input conditions for the study of starved contacts can be achieved with such test rig configuration.
• VRBKA, M.; KŘUPKA, I.; SVOBODA, P.; ŠPERKA, P.; NÁVRAT, T.; HARTL, M.; NOHAVA, J.:
  Effect of shot peening on rolling contact fatigue and lubricant film thickness within mixed lubricated non-conformal rolling/sliding contacts,
  Tribology International, Vol.44, (2011), No.12, pp.1726-1735, ISSN 0301-679X, Elsevier
  journal article - other
  The effect of shot peening on rolling contact fatigue (RCF) and lubricant film thickness within nonconformal rolling/sliding contacts operated under mixed lubrication conditions was observed in this study. Rolling contact fatigue tests and film thickness measurements were carried out using specimens with modified surface topography by shot peening process using glass beads having diameter between 0.07 and 0.11 mm. It has been shown that the effect of shot peening on RCF has no positive effect even if shot peened surface of the roller exhibited somewhat higher hardness in contrast to the grounded surface. The reduction of RCF may be caused due to asperities interactions because after shot peening the surface roughness of the roller was increased. Film thickness measurements confirmed that the contact is realized actually only between asperity peaks of shot peened ball and smooth disc. Conversely, no negative effect on RCF was observed when the shot peened surface of the roller was polished. The polish of asperity peaks causes the creation of lands and micro-cavities, which may be employed as lubricant micro-reservoirs. From film thickness measurements it has been observed that lubricant emitted by shallow micro-cavities can provide the local increase in lubrication film thickness, which thereby reduces asperities interactions. Similar results were obtained for start-up conditions where the squeeze lubricant enlarges film thickness and reduces surface interactions. From the obtained results, it can be suggested that properly designed surface topography modification could help to increase the efficiency of lubrication films leading to the enhancement of contact fatigue life of non-conformal mixed lubricated rolling/sliding contacts.
• KŘUPKA, I.; HARTL, M.; BAIR, S.; SVOBODA, P. ;KUMAR, P.:
  Mechanical Degradation of the Liquid in an Operating EHL Contact,
  Tribology Letters, Vol.40, (2010), No.3, pp.1-7, ISSN 1023-8883, Springer
  journal article - other
  Elastohydrodynamic lubrication (EHL) calculations using the real pressure and real shear dependence of viscosity have revealed that the shear and load dependences of film thickness are often greater than the classical prediction. Experimental measurements have confirmed the increased sensitivity to scale and load; however, the sensitivities are even greater than would be expected from shear-thinning. Time-dependent film thickness measurements and stress-history-dependent flow curves are employed to show that molecular degradation may occur at nominal rolling EHL stress levels and that this degradation affects the film thickness.
• KŘUPKA, I.; SVOBODA, P.; HARTL, M.:
  Effect of surface topography on mixed lubrication film formation during start up under rolling/sliding conditions,
  Tribology International, Vol.43, (2009), No.4, pp.1-9, ISSN 0301-679X, Elsevier
  journal article - other
  The start up operation of mixed lubricated contacts represents one of the transient conditions that bring the risk of the surface damage because of asperities interactions. This paper focuses on the effects of both artificially produced and real roughness features on mixed lubrication film formation during start up of non-conformal contacts operated under rolling/sliding conditions. Chromatic interferograms captured during start up enabled the detailed changes in lubrication film caused by surface features to be observed. The observation of the effects of surface dents artificially produced on the ball surface helped to better understand the behaviour of real surface topography. It was found that the presence of shallow surface features can help to separate mixed lubricated rubbing surfaces more efficiently than it could be suggested from the results obtained with smooth surfaces.
• KŘUPKA, I.; HARTL, M.; SVOBODA, P.:
  Effects of surface topography on lubrication film formation within elastohydrodynamic and mixed lubricated non-conformal contacts,
  PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY, Vol.223, (2009), No.6, pp.1-9, ISSN 1350-6501, Professional Engineering Publishing
  journal article - other
  This paper focuses on the effects of surface topography modifications on lubrication film thickness within non-conformal lubricated contact. Optical test rig is used to study the lubricant film behavior between the flat surface of a chromium coated glass disc and a steel ball. An array of micro-dents was produced on the ball surface to be able to demonstrate the effect of surface topography on lubrication film formation. Experiments were carried out under elastohydrodynamic and mixed lubrication using steady state and transient operational conditions (start up and reversal motion). Obtained results have shown that surface texturing could represent the way how to increase lubrication efficiency of rolling/sliding non-conformal contacts under operational conditions when lubrication film is not able separate rubbing surfaces. Lubricant emitted from the micro-dent helps to reduce the asperities interaction. Moreover, the effect of surface micro-cavities has been observed within starved non-conformal contact under pure rolling conditions. An increase in film thickness within severe starved contact was localized upstream micro-dents that was recently predicted numerically. This effect was further amplified as lubricant released from micro-dent remains on the ball surface and again enters the contact after the ball turns round.