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5 results on '"Horsák, Lukáš"'

1. Long-term testing of textile material - Methodology of testing and design of the testing equipment.

Author

Freiherrová, Nela, Horňáková, Marie, Kawulok, Marek, Juračka, David, Mareš, Vratislav, and Horsák, Lukáš

Subjects
MATERIALS testing, TESTING equipment, TEST design, TEXTILE design, ENGINEERING design, CIVIL engineering, PRESTRESSED concrete
Abstract

The application of coating fabrics as roofing structures has become very popular lately. The materials are specially designed to withstand external loads at very low self-thickness and very low self-weight. The material's surface creates a membrane, which needs to be mechanically prestressed to become a load-bearing part of the system. However, due to the long-term prestress of the material and exposure to the environment (e.g., the snow season), the long-term characteristics of the material need to be considered, tested, and evaluated. This contribution is focused on the research of the methodology of long-term tests of the fabric material used for civil engineering and experimental design and manufacturing of particular testing equipment which will be used subsequently for the long-term testing of the fabrics. [ABSTRACT FROM AUTHOR]

Published
2023
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3. Fracture Toughness and Charpy Impact Test of MIM Steels and Correlation of Results by KIC- CVN Relationships

Author

Tomášek, Radek, Mareš, Vratislav, and Horsák, Lukáš

Abstract

This paper presents results of fracture toughness and Charpy impact tests of 4 steels prepared by metal injection moulding (MIM) method: AISI 4140, 4605, 17-4 PH and SS 420W Grade. Charpy impact testing was performed on the series of machined specimens with sub-size cross-section to obtain values of CVN impact energy. Fracture toughness test method according to ASTM E1820 was performed on SENB specimens, fatigue pre-cracked, to obtain values of KIC. All tests were performed at the room temperature. After the material testing, next step was to evaluate the results and apply known correlation relationships between fracture toughness KIC and Charpy impact CVN energies. Many empirical relations exist and describe existence of such relationship. Procedure was used to correlate energies of sub-size Charpy specimens to full-size specimens. Several proposed correlation relationships from transition and upper shelf region of transition curve were used, where the best correlation was found to be Robert-Newtons with average deviation of 22% in comparison to tested values.

Published
2019
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4. Using of abrasive water jet for measurement of residual stress in railway wheels

Author

Hlaváček, Petr, Brumek, Jan, and Horsák, Lukáš

Subjects
abrasive water jet, railway wheel, musculoskeletal, neural, and ocular physiology, zaostala naprezanja, željeznički kotač, residual stress, human activities, abrazivni vodeni mlaz
Abstract

The paper provides a general introduction to methods of measurement of residual stresses on railway wheels. Determination of residual stress distribution is necessary for the prediction of wheel service life and possible catastrophic failure. Therefore experimental section is devoted to residual stress measurement using strain gauges according to standard EN 13262 + A1. During measurement, several segments of tested wheel were cut by abrasive water jet to detect changes of residual stresses on specified places. It was found that abrasive water jet technology can cut wheel segments faster, more accurately and with negligible mechanical and thermal load compared to mechanical cutting by band saw. Therefore the use of abrasive water jet is recommended for the measurement of residual stresses in railway wheels. The paper provides a general introduction to methods of measurement of residual stresses on railway wheels. Determination of residual stress distribution is necessary for the prediction of wheel service life and possible catastrophic failure. Therefore experimental section is devoted to residual stress measurement using strain gauges according to standard EN 13262 + A1. During measurement, several segments of tested wheel were cut by abrasive water jet to detect changes of residual stresses on specified places. It was found that abrasive water jet technology can cut wheel segments faster, more accurately and with negligible mechanical and thermal load compared to mechanical cutting by band saw. Therefore the use of abrasive water jet is recommended for the measurement of residual stresses in railway wheels. Web of Science 19 2 390 387

Published
2012

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