doc. Ing. Tomáš Návrat, Ph.D.
E-mail:   navrat@fme.vutbr.cz  WWW:   http://www.old.umt.fme.vutbr.cz/~tnavrat Dept.:   Institute of Solid Mechanics, Mechatronics and Biomechanics Position:   Deputy Director for Educational Activities Room:   A2/610 Dept.:   Institute of Solid Mechanics, Mechatronics and Biomechanics Dept. of Engineering Mechanics Position:   Associate Professor Room:   A2/610

Supervised courses:

• Modelling in Engineering Practice (RMV)
• Reliability of Structures (RST)
• Reliability of Structures (RST-A)
• Solution of Basic Problems of Solids Mechanics by FEM (6KP-A)
• Solution of Basic Problems of Solids Mechanics by FEM (6KP)
• Solution of Basic Problems of Solids Mechanics by FEM (6KP-A)
• Solution of Basic Problems of Solids Mechanics by FEM (6KP-K)
• Strength of Materials I (4PP)
• Strength of Materials I (4PP)
• Strength of Materials I (4PP-A)
• Strength of Materials I (4PP-A)
• Strength of Materials I (4PP-K)

Publications:

• PETRUŠKA, J.; NÁVRAT, T.; ŠEBEK, F.:
  Novel approach to computational simulation of cross roll straightening of bars
  journal article in Web of Science
• KELBL, M.; KOČIŠ, J.; VESELÝ, R.; FLORIAN, Z.; NÁVRAT, T.; VOSYNEK, P.:
  Biomechanical Testing of Spinal Segment Fixed by Arcofix System on the Swine Spine, Korean Society of Spine Surgery
  journal article in Web of Science
• VRBKA, M.; NÁVRAT, T.; KŘUPKA, I.; HARTL, M.; ŠPERKA, P.; GALLO, J.:
  Study of film formation in bovine serum lubricated contacts under rolling/sliding conditions, SAGE Publications Ltd
  journal article in Web of Science
• JANŮ, I.; KOČIŠ, J.; NÁVRAT, T.; FLORIAN, Z.; WENDSCHE, P.:
  Srovnávací analýza šroubů Socon CS a Socon v ošetření osteoporotických zlomenin torakolumbální páteře - biomechanická studie,
  Acta Chirurgie Orthopaedicae et Traumatologie Čechoslovaca, Vol.78, (2011), No.4, pp.334-338, ISSN 0001-5415, Česká společnost pro ortopedii a traumatologii
  journal article - other
• 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
• ČIŽMÁŘ, I.; FLORIAN, Z.; NÁVRAT, T.; PALOUŠEK, D.:
  A biomechanical study of a suture between the deltoid muscle and a free tendon graft for reconstruction of the elbow extension, PALACKY UNIV, MEDICAL FAC, CENTRAL LIBRARY, HNEVOTINSKA 3, OLOMOUC, CZECH REPUBLIC
  journal article in Web of Science
• URBANOVÁ, L.; SRNEC, R.; PROKS, P.; STEHLÍK, L.; FLORIAN, Z.; NÁVRAT, T.; NEČAS, A.:
  Comparison of the Resistance to Bending Forces of the 4.5 LCP Plate-rod Construct and of 4.5 LCP Alone Applied to Segmental Femoral Defects in Miniature Pigs,
  ACTA VETERINARIA BRNO, Vol.79, (2010), No.4, pp.613-620, ISSN 0001-7213, University of Veterinary and Pharmaceutical Sciences in Brno
  journal article - other
• KOČIŠ, J.; NÁVRAT, T.; FLORIAN, Z.; WENDSCHE, P.:
  Biomechanical testing of spinal segment fixed by thoracolumbar spine locking plate on the swine lumbar spine,
  Biomedical Papers, Vol.154, (2010), No.4, pp.345-354, ISSN 1213-8118, Palacký University
  journal article - other
• VRBKA, M.; ŠAMÁNEK, O.; ŠPERKA, P.; NÁVRAT, T.; KŘUPKA, I.; HARTL, M.:
  Effect of surface texturing on rolling contact fatigue within mixed lubricated non-conformal rolling/sliding contacts, Elsevier
  journal article in Web of Science

List of publications at Portal BUT

Abstracts of most important papers:

• VRBKA, M.; NÁVRAT, T.; KŘUPKA, I.; HARTL, M.; ŠPERKA, P.; GALLO, J.:
  Study of film formation in bovine serum lubricated contacts under rolling/sliding conditions, SAGE Publications Ltd
  journal article in Web of Science
  The aim of this study is to perform a detailed experimental analysis of lubricant film thickness of bovine serum within the contact between the artificial metal and ceramic heads (balls) and the glass disc to analyse the effect of proteins on film formation under various rolling/sliding conditions. Lubricant film observation of bovine serum solutions was carried out using an optical test rig. Chromatic interferograms were recorded with a high-speed CMOS digital camera and evaluated with thin film colorimetric interferometry. Film thickness was studied as a function of time. Under pure rolling conditions, film thickness increases with time as well as with rolling distance for all mean speeds and for both materials of the balls; however the metal ball always forms a thicker lubricating film in comparison to the ceramic ball. Under rolling/sliding conditions, when the disc is faster than the ball, the formation of lubricant film thickness is different compared to pure rolling conditions. At first, film thickness increases rapidly with a rolling/sliding distance for all mean speeds. When maximum film thickness is reached, then this effect is lost and film thickness starts to fall and finally, at the end of the measurement, film thickness drops down to a few nanometres. For the metal ball, maximum values of central film thicknesses are proportional to the mean speed; however this is not observed with the ceramic ball. An absolutely different formation of bovine serum film thickness is observed when the ball is faster than the disc. Under this condition, the protein layer is very thin for both materials of balls, and central film thickness reaches only about a few nanometres. Local protein spots are formed in a very small area of the contact zone and reach the thickness between 20 and 25 nm for the metal ball and 5 nm for the ceramic ball. From the performed experiments under rolling/sliding conditions, it is obvious that the formation of lubricant film thickness is markedly dependent on kinematic conditions acting in the contact, especially on the positive and negative slide-to-roll ratio and the mean speed. In addition, the material of the artificial head has a certain influence on the formation of bovine serum lubricating film.
• JANŮ, I.; KOČIŠ, J.; NÁVRAT, T.; FLORIAN, Z.; WENDSCHE, P.:
  Srovnávací analýza šroubů Socon CS a Socon v ošetření osteoporotických zlomenin torakolumbální páteře - biomechanická studie,
  Acta Chirurgie Orthopaedicae et Traumatologie Čechoslovaca, Vol.78, (2011), No.4, pp.334-338, ISSN 0001-5415, Česká společnost pro ortopedii a traumatologii
  journal article - other
  The purpose of the study is compare the anchorage strength of Socon CS cannulated pedicle screws (B. Braun, Aesculap) with that of Socon screws in human cadaver vertebrae, using pull-out strength testing. MATERIAL Twelve samples involving T12 to L3 vertebrae were prepared and a total of 20 pedicle screws, 10 Socon CS and 10 Socon screws, were inserted in them. All screws were 55 mm in length and 6 mm in diameter. The results of this study confirm the hypothesis that the anchorage of Socon CS cannulated pedicle screws with bone cement augmentation is disrupted by significantly higher pull-out strength than that of Socon screws, when subjected to monotonous loading.
• ČIŽMÁŘ, I.; FLORIAN, Z.; NÁVRAT, T.; PALOUŠEK, D.:
  A biomechanical study of a suture between the deltoid muscle and a free tendon graft for reconstruction of the elbow extension, PALACKY UNIV, MEDICAL FAC, CENTRAL LIBRARY, HNEVOTINSKA 3, OLOMOUC, CZECH REPUBLIC
  journal article in Web of Science
  It is possible to reconstruct the elbow motion in tetraplegic patients using the posterior portion of the deltoid muscle. In this surgery however, it is a problem to achieve a firm suture between the deltoid muscle and the tendon graft which extends the muscle and is sewn in order to compensate for the plegic musculus triceps brachii function. This study assesses two methods of attachment between muscle and free tendon graft from the biomechanical point of view.
• URBANOVÁ, L.; SRNEC, R.; PROKS, P.; STEHLÍK, L.; FLORIAN, Z.; NÁVRAT, T.; NEČAS, A.:
  Comparison of the Resistance to Bending Forces of the 4.5 LCP Plate-rod Construct and of 4.5 LCP Alone Applied to Segmental Femoral Defects in Miniature Pigs,
  ACTA VETERINARIA BRNO, Vol.79, (2010), No.4, pp.613-620, ISSN 0001-7213, University of Veterinary and Pharmaceutical Sciences in Brno
  journal article - other
  The study deals with the determination of mechanical properties, namely resistance to bending forces, of flexible buttress osteosynthesis using two different bone-implant constructs stabilizing experimental segmental femoral bone defects (segmental ostectomy) in a miniature pig ex vivo model using 4.5 mm titanium LCP and a 3 mm intramedullary pin ("plate and rod" construct) (PR-LCP), versus the 4.5 mm titanium LCP alone (A-LCP). The "plate and rod" fixation (PR-LCP) of the segmental femoral defect is significantly more resistant (p < 0.05) to bending forces (200 N, 300 N, and 500 N) than LCP alone (A-LCP). Stabilisation of experimental segmental lesions of the femoral diaphysis in miniature pigs by flexible bridging osteosynthesis 4.5 mm LCP in combination with the "plate and rod" construct appears to be a suitable fixation of non-reducible fractures where considerable strain of the implants by bending forces can be assumed. These findings will be used in upcoming in vivo experiments in the miniature pig to investigate bone defect healing after transplantation of mesenchymal stem cells in combination with biocompatible scaffolds.
• KOČIŠ, J.; NÁVRAT, T.; FLORIAN, Z.; WENDSCHE, P.:
  Biomechanical testing of spinal segment fixed by thoracolumbar spine locking plate on the swine lumbar spine,
  Biomedical Papers, Vol.154, (2010), No.4, pp.345-354, ISSN 1213-8118, Palacký University
  journal article - other
  The aim of the experiment was to compare the mechanical properties of intact spinal segment with impaired intervertebral disc and impaired intervertebral disc fixed by TSLP (Thoracolumbar Spine Locking Plate).