Number of found documents: 1301
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Průzkum Přibyslavské štoly zemním radarem
Válek, Jan; Kotková, Kristýna; Kozlovcev, Petr
2023 - Czech
Byl realizován nedestruktivní průzkum Přibyslavské štoly pomocí zemního radaru. Cílem měření bylo ověření existence případných prostor skrytých pod současným povrchem štoly. Průzkum lokalizoval násyp nad skalním podložím štoly a další nehomogenity. A non-destructive survey of the Přibyslav underground corridor using ground penetrating radar was carried out. The aim of the measurement was to verify the existence of possible structures hidden under the current surface of the corridor. The survey located the backfill above the bedrock of the underground corridor and other changes in the structure. Keywords: ground penetrating radar (GPR); cultural heritage; non-destructive testing Available at various institutes of the ASCR
Průzkum Přibyslavské štoly zemním radarem

Byl realizován nedestruktivní průzkum Přibyslavské štoly pomocí zemního radaru. Cílem měření bylo ověření existence případných prostor skrytých pod současným povrchem štoly. Průzkum lokalizoval násyp ...

Válek, Jan; Kotková, Kristýna; Kozlovcev, Petr
Ústav teoretické a aplikované mechaniky, 2023

Fast continuous in-situ XCT of additively manufactured carbon fiber reinforced tensile test specimens
Glinz, J.; Maurer, J.; Holzleitner, M.; Pace, F.; Stamopoulos, A.; Vopálenský, Michal; Kumpová, Ivana; Eckl, M.; Kastner, J.; Senck, S.
2023 - English
The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific application’s needs. However, the bonding quality between continuous fibers and the FFF matrix material has high impact on the overall performance of the composite. In a recent study [1], additively manufactured (AM) continuous fiber reinforced tensile test specimens have been investigated regarding the effect of amount and material of the embedded continuous fibers on tensile strength and AM build quality. During these tensile tests, a sudden reduction in tensile stress, which most likely was not related to actual rupture of continuous fibers, was noticeable. Since X-ray computed tomography (XCT) scans were performed only prior to and after the tensile testing, a detailed investigation on the origin of these drops in tensile stress was not possible. Within this work, we will expand upon these findings and present results of fast on-the-fly in-situ investigations performed on continuous carbon fiber reinforced specimens of the same AM build. During these investigations, specimens are loaded under the same conditions while fast XCT scans, with a total scan time of 12 seconds each, were performed consecutively. The resulting three-dimensional image data reveals internal meso- and macro-structural changes over time/strain to find the cause of the aforementioned reduction in tensile stress. Keywords: additive manufacturing; composites; X-ray computed tomography; in-situ tensile testing Available at various institutes of the ASCR
Fast continuous in-situ XCT of additively manufactured carbon fiber reinforced tensile test specimens

The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific application’s needs. However, ...

Glinz, J.; Maurer, J.; Holzleitner, M.; Pace, F.; Stamopoulos, A.; Vopálenský, Michal; Kumpová, Ivana; Eckl, M.; Kastner, J.; Senck, S.
Ústav teoretické a aplikované mechaniky, 2023

The effect of the backfill on the integrity of a buried pipeline upon heavy-duty vehicle crossings
Gajdoš, Lubomír; Šperl, Martin; Slížková, Zuzana; Drdlová, M.
2023 - English
The aim of this work was to determine stresses in the wall of a buried empty gas pipeline caused by the weight of backfill as well as by heavy-duty vehicles crossing the pipeline, and, on their basis to assess the applicability of protective sleeves. A buried pipeline with zero internal pressure of transported medium (empty pipeline) differs from an unburied pipeline by the vertical load due to the weight of the backfill which causes an ovalness of the circular cross section of the pipeline. This leads to the rise of through-wall bending stresses with the tensile stress at the outside surface at the 3 and 9 o´clock positions and compressive stress at the inside surface. At the 6 and 12 o´clock positions the stresses are tensile at the inside surface and compressive at the outside surface. The current depth of soil cover above gas pipelines is 0.5 m. For pipes DN500, t ~ 6.5 mm the through-wall bending stress is found to be σb ≈ ±10 MPa. In comparison with the yield stress of pipeline material, this stress is negligible. The situation is changed when heavy-duty vehicles cross the pipeline. For example, when a MAN truck with the mass load 3270 kg acting on a single wheel of the front axle crosses this pipeline, the pressure transmitted to the pipe will cause the through-wall bending stress σb ≈ ±76 MPa. This stress is superimposed to that of the backfill to give the total value ±86 MPa. When dead loads, imposed by backfill cover, together with live loads, caused by truck-wheel loads, are excessive a crushing of side walls of the pipeline and/or ring buckling of the pipe cross section can happen. Keywords: gas pipeline; pressure; buried pipeline Available at various institutes of the ASCR
The effect of the backfill on the integrity of a buried pipeline upon heavy-duty vehicle crossings

The aim of this work was to determine stresses in the wall of a buried empty gas pipeline caused by the weight of backfill as well as by heavy-duty vehicles crossing the pipeline, and, on their basis ...

Gajdoš, Lubomír; Šperl, Martin; Slížková, Zuzana; Drdlová, M.
Ústav teoretické a aplikované mechaniky, 2023

Laboratorní mikroskopický průzkum stratigrafie barevných nátěrů na stavebních materiálech budovy Morzinského paláce v Nerudově ulici v Praze 1
Slížková, Zuzana; Náhunková, Pavla; Bauerová, Pavla; Vondráčková, Michaela
2023 - Czech
Stratigrafická analýza barevných nátěrů na fasádě Morzínského paláce v Praze za účelem určení barevnosti fasády pro návrh obnovy a restaurování budovy. Stratigraphic analysis of the color coatings on the facade of the Morzín Palace in Prague in order to determine the color of the facade for the future restoration of the building. Keywords: stratigraphy; colored layers; coatings; microscopy Available at various institutes of the ASCR
Laboratorní mikroskopický průzkum stratigrafie barevných nátěrů na stavebních materiálech budovy Morzinského paláce v Nerudově ulici v Praze 1

Stratigrafická analýza barevných nátěrů na fasádě Morzínského paláce v Praze za účelem určení barevnosti fasády pro návrh obnovy a restaurování budovy....

Slížková, Zuzana; Náhunková, Pavla; Bauerová, Pavla; Vondráčková, Michaela
Ústav teoretické a aplikované mechaniky, 2023

Výsledky mikroskopické analýzy vzorků malt odebraných z objektů: věž kláštera v Sázavě, Apolinář v Praze
Bauerová, Pavla; Frankeová, Dita; Vondráčková, Michaela
2023 - Czech
omocí elektronového mikroskopu a EDS analýzy byly zkoumány vzorky ze dvou lokalit - vzorek malty z věže kláštera v Sázavě a dva vzorky omítky z objektu Apolinář v Praze (Apolinář – líc, Apolinář – půda). Cílem zkoumání bylo zejména určit druh pojiva omítek a nátěrů na omítce. Ve všech třech analyzovaných vzorcích bylo identifikováno silně hydraulické pojivo. Using an electron microscope and EDS analysis, samples from two locations were examined - a sample of mortar from the tower of the monastery in Sázava and two samples of plaster from the Apolinař building in Prague (Apolinář - face, Apolinář - soil). The aim of the investigation was to determine the type of binder for plasters and coatings on plaster. A strongly hydraulic binder was identified in all three analyzed samples. Keywords: microscopy; EDS analysis; mortars Available at various institutes of the ASCR
Výsledky mikroskopické analýzy vzorků malt odebraných z objektů: věž kláštera v Sázavě, Apolinář v Praze

omocí elektronového mikroskopu a EDS analýzy byly zkoumány vzorky ze dvou lokalit - vzorek malty z věže kláštera v Sázavě a dva vzorky omítky z objektu Apolinář v Praze (Apolinář – líc, Apolinář – ...

Bauerová, Pavla; Frankeová, Dita; Vondráčková, Michaela
Ústav teoretické a aplikované mechaniky, 2023

Experimental evaluation of aluminothermic welds
Zeman, L.; Valach, J.; Zlámal, P.; Krčmářová, N.; Koudelková, Veronika; Zeman, J.
2023 - English
The article presents a study of the mechanical processes occurring during the aluminother-mic reaction using experimental methods (strain gauges, digital image correlation, thermography,scanning electron microscopy, profilometry). The aluminothermic reaction is a highly efficient weldingmethod due to its exothermic behaviour, however, it places considerable demands not only on thewelding technique, but also on the capabilities of the experimental methods used - these limitationsare also discussed in the article. The aluminothermic reaction is associated with the formation of alocalised heat source with a time evolution dictated by the technological procedure, which manifestsitself in heat propagation to the surrounding weld material. The unequal evolution of the temperaturefield is the fundamental cause of the appearance of the heat affected zone or local deformations orsurface curvature, which was the focus of the experimental methods deployed above and the results ofwhich are shown in the article. Keywords: aluminothermic reaction; train gauges; hardness; profilometry; scanning electron microscope Available at various institutes of the ASCR
Experimental evaluation of aluminothermic welds

The article presents a study of the mechanical processes occurring during the aluminother-mic reaction using experimental methods (strain gauges, digital image correlation, thermography,scanning ...

Zeman, L.; Valach, J.; Zlámal, P.; Krčmářová, N.; Koudelková, Veronika; Zeman, J.
Ústav teoretické a aplikované mechaniky, 2023

Acta Polytechnica CTU Proceedings. Vol. 42 (2023)
Kytýř, Daniel; Doktor, T.; Zlámal, Petr
2023 - English
The YSESM symposium provides a forum for young researchers and engineers, PhD students and students dealing with subjects of experimental mechanics. The Symposium concentrates on current work in all areas of experimental research and its application in solid and fluid mechanics. The topic will particularly concern to: Conventional and Advanced Experimental Methods in Solid and Fluid Mechanics, Non-Destructive Testing and Inspection, Measurements in Material Science, Computer Assisted Testing and Simulation, Engineering Design Simulation, Hybrid Methods, Experimental Techniques – Numerical Simulation, Optical Methods and Image Processing, Measurements in Biomechanics, Sensor Techniques for Micro- and Nano-Applications, Measurement Methods for Forensic Engineering. Keywords: experimental mechanics; fluid mechanics; mechanics of solids Available at various institutes of the ASCR
Acta Polytechnica CTU Proceedings. Vol. 42 (2023)

The YSESM symposium provides a forum for young researchers and engineers, PhD students and students dealing with subjects of experimental mechanics. The Symposium concentrates on current work in all ...

Kytýř, Daniel; Doktor, T.; Zlámal, Petr
Ústav teoretické a aplikované mechaniky, 2023

Conductive open-cell silicone foam for modulatable damping and impact sensing applications
Preuer, R.; Šleichrt, Jan; Kytýř, Daniel; Graz, I.
2023 - English
Nature has long served as a source of inspiration for the development of new materials, with foam-like structures in fruits such as oranges and pamelos serving as examples of efficient energy dissipation. In this study, we present the synthesis and characterization of a conductive silicone foam for potential impact sensing applications. By blending Sylgard 184 and Carbon Black, we create a highly porous structure capable of dissipating energy and modulating its resistance. To investigate the properties of the foam, we utilized both micro-computer tomography (μCT) and scanning electron microscopy (SEM) imaging techniques. The μCT imaging revealed the intricate pore network of the foam, reminiscent of the complex structure found in natural sponges. SEM imaging allowed for observation of the uniform distribution of Carbon Black particles within the foam, enabling the conductive properties of the foam. The foam’s mechanical behavior was characterized by a compression test under μCT imaging to measure the deformation behavior and changes in the foam’s resistance. Additionally, a ball drop test was conducted to investigate the foam’s damping behavior while simultaneously measuring the impact location by the local change in resistance. Remarkably, our results demonstrate the exceptional damping capabilities of the conductive silicone foam, with the damping ratio modulated by adjusting the degree of compression-induced deformation. This is attributed to the collapse of the foam’s porous structure, resulting in a significant increase in the foam’s contact area. Overall, our study provides valuable insights into the behavior of conductive silicone foams and their potential as an impact sensing material. The use of both CT and SEM imaging techniques allows for a comprehensive understanding of the foam’s properties, which can be optimized for a variety of applications. The foam’s ability to modulate its damping properties by adjusting the degree of deformation provides a promising avenue for future research in the field of materials science and engineering. Keywords: silicone foam; conductive properties; deformation behaviour; damping Available at various institutes of the ASCR
Conductive open-cell silicone foam for modulatable damping and impact sensing applications

Nature has long served as a source of inspiration for the development of new materials, with foam-like structures in fruits such as oranges and pamelos serving as examples of efficient energy ...

Preuer, R.; Šleichrt, Jan; Kytýř, Daniel; Graz, I.
Ústav teoretické a aplikované mechaniky, 2023

Characterization of five mosaic mortar beds from Austria produced by A. Neuhauser/Tiroler Glasmalerei and J. Pfefferle
Bauerová, Pavla; Frankeová, Dita; Slížková, Zuzana
2023 - English
The report contains the results of material analyses of five mortar beds of mosaics produced by the Austrian studios Neuhauser/Tiroler Glasmalerei and Josef Pfefferle. The analysed samples come from mosaics made at the turn of the 19th and 20th centuries and located in various places in Tyrol. The mortars were analysed by SEM-EDS and thermal analysis. The results showed that, in addition to traditional materials such as marble dust, they also contain atypical or innovative components such as waste ceramic and glass shards or early Portland cement. Keywords: SEM-EDS analysis; historic mortar; mosaic; thermal analysis Available at various institutes of the ASCR
Characterization of five mosaic mortar beds from Austria produced by A. Neuhauser/Tiroler Glasmalerei and J. Pfefferle

The report contains the results of material analyses of five mortar beds of mosaics produced by the Austrian studios Neuhauser/Tiroler Glasmalerei and Josef Pfefferle. The analysed samples come from ...

Bauerová, Pavla; Frankeová, Dita; Slížková, Zuzana
Ústav teoretické a aplikované mechaniky, 2023

Vyšetření základních mechanických a lomově-mechanických vlastností vzorků odebraných z VTL plynovodu – lokalita L177/2 po čtrnáctiměsíční expozici ve vlhkém vodíku při tlaku 3 MPa
Gajdoš, Lubomír; Šperl, Martin; Šorm, Filip; Bejdl, Jan
2022 - Czech
Vyšetření vlivu vlhkého vodíku stlačeného na tlak 3 MPa na mechanické a lomové vlastnosti plynovodní oceli ČSN 13126, tahové vzorky, Charpy vzorky i CT vzorky byly během expozice ve vlhkém vodíku trvale zatíženy, po čtrnácti měsících expozice byl zjištěn pokles tažnosti tahových vzorků, pokles lomových parametrů Jin a J0,2 a mírné zvýšení parametru Jm. Investigation of the effect of moist hydrogen pressurized to 3 MPa on mechanical and fracture properties of gas pipeline steel ČSN 13126, tensile specimens, Charpy specimens and CT specimens were kept loaded during the exposition in moist hydrogen, after a fourteen months exposition it was found that ductility of tensile specimens and fracture parameters Jin and J0,2 of CT specimens decreased whilst the parameter Jm was slightly increased.\n Keywords: stress-strain diagram; Ramberg-Osgood dependence; impact strength; fracture toughness Available at various institutes of the ASCR
Vyšetření základních mechanických a lomově-mechanických vlastností vzorků odebraných z VTL plynovodu – lokalita L177/2 po čtrnáctiměsíční expozici ve vlhkém vodíku při tlaku 3 MPa

Vyšetření vlivu vlhkého vodíku stlačeného na tlak 3 MPa na mechanické a lomové vlastnosti plynovodní oceli ČSN 13126, tahové vzorky, Charpy vzorky i CT vzorky byly během expozice ve vlhkém vodíku ...

Gajdoš, Lubomír; Šperl, Martin; Šorm, Filip; Bejdl, Jan
Ústav teoretické a aplikované mechaniky, 2022

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