Jindrich Vilis
@unob.cz
Scopus Publications
Scopus Publications
Radim Kupčák, Jan Zouhar, Jindřich Viliš, Lukáš Gregor, and Denisa Hrušecká
MDPI AG
This article aims to investigate the accuracy and dimensional stability of bonded metal and CFRP (Carbon Fibre Reinforced Plastic) adherends. The motivation behind this study was to assess the suitability of CFRP for optical devices through the evaluation of precision bonding technology. A binocular was selected as a reference optical device. A technological sample was designed, with required total runout of key dimensions 0.05 mm. The sample underwent testing according to ISO 9022-1. The total runout was evaluated after production and environmental tests. Eight out of 15 samples were turned after gluing due to insufficient accuracy. None of the turned samples exceeded the total runout deviation of 0.01 mm, and the average value of the maximal deviation was 0.0041 mm. The noncalibrated samples performed significantly worse with the average value of the maximal deviation of 0.0164 mm. The measurements during the climatic tests showed that the largest deviation (on average 77.6% of the maximum achieved deviation) occurs at the first temperature loading. Subsequent temperature cycles caused lower deviations. The results highlight the significance of addressing deformations resulting from adhesive volume shrinkage-induced stress as a crucial factor in precision bonding technology.
Jindřich Viliš, Vlastimil Neumann, Roman Vítek, Jan Zouhar, Zdeněk Pokorný, and Milan Marek
MDPI AG
This article deals with the ballistic impact of the 7.62 mm FMJ M80 rifle projectile into the laminated Twaron/UHMWPE composite armor. The armor composition consisted of composite panels made from Twaron CT 747 para-aramid fabric and ultra-high-molecular-weight Endumax Shield XF33 polyethylene. To analyze the ballistic impact and to verify the resistance of the designed armor according to the NATO AEP 4569 STANAG standard, protection level 1, 7.62 × 51 mm FMJ NATO M80 rifle cartridges with lead projectiles were used in the ballistic experiment. After the projectile impact, the damage failure mechanisms of the composite panels were documented. As part of the evaluation of the experiments, the initial microstructure of the composite panels was documented, and subsequently, the damaged areas of the composite armor after the ballistic experiment were also documented. Optical and scanning electron microscopy were used to document the structures. The important parameter of composite armor is its mechanical properties. The surface hardness of the composite panels was measured by the Shore D method using the hardness tester DIGI-Test II. The results obtained from the ballistic experiment demonstrate that the designed Twaron/Endumax armor was not penetrated. This armor has sustained multiple impacts for all three 7.62 mm FMJ M80 projectiles and is suitable for the construction of armor protection.
Jindřich Viliš, Roman Vítek, Jan Zouhar, Michal Stejskal, and Vlastimil Neumann
Jan Evangelista Purkyne University in Usti nad Labem
Jindřich Viliš, Zdeněk Pokorný, Jan Zouhar, and Miroslav Jopek
Jan Evangelista Purkyne University in Usti nad Labem
abstract
Jiri Prochazka, Jindrich Vilis, David Dobrocky, and Petr Sperka
Jan Evangelista Purkyne University in Usti nad Labem
Keywords The article deals with a possibilities of an enhancement of functional properties of highly stressed components by specific combination of surface technology. Two surface technologies such as plasma nitriding and laser shock peening were selected for the experiment. Those technologies were applied upon steel 42CrMo4 frequently utilized in manufacturing of strained components. Properties obtained by applied surface technologies were tested by following experimental methods. The chemical composition was verified by optical emission spectrometer Tasman Q4 Bruker. The surface morphology was inspected by scanning electron microscope TESCAN MIRA 4. The microstructure of heat treated as well as of nitrided specimens was observed by opto-digital microscope Olympus DSX500i. The microhardness profiles were measured by microhardness tester LM247 AT LECO. The friction coefficient was tested on tribometer Bruker UMT-3 TriboLab. For an assessment of the surface wear-resistance the profilometer Talysurf CLI 1000 and Contour GT were utilized. The experimental results show that although the proposed surface technology combination manifests itself to be disadvantageous, both technology LSP, as well as plasma nitriding, applied separately,
Jindřich VILIŠ, Zdeněk POKORNÝ, and Jan ZOUHAR
TANGER Ltd.
Z. Studeny, D. Dobrocky, J. Viliš, and J. Adam
IOP Publishing
The paper works with ultra-high molecular weight polyethylene (UHMW). This polyethylene is widely used in technology, in engineering or its applications are also in the field of medicine in prosthetics in the lining of joint replacements. This wide use is mainly due to its properties. It is mainly its abrasion resistance and very low coefficient of friction (COF), so it has excellent sliding properties. It is these properties that are the subject of research on UHMW polyethylene. The investigation of these properties is always linked in tribological tests to the material in the friction pair, which consists of the material under test (UHMW) and the indenter. For the purpose of tribological testing, 6.35 mm diameter balls of ZrO2 ceramic material and a cobalt-chromium alloy known as Stellit 6 were chosen as indentors. Practical applications are the above mentioned fields of technology, engineering, etc.
J Viliš, Z Pokorný, J Zouhar, R Vítek, and J Procházka
IOP Publishing
In this study, the ballistic resistance of composite panels made of solid fabrics was investigated. In the experimental part, the materials Twaron CT 747 TH110 impregnated with thermoplastic resin and Twaron CT 747 impregnated with thermoset resin were examined. The ballistic resistance of the composite panels was tested in the reduced version according to the NATO AEP-55 STANAG 4569 standard, protection level 1. The manufactured composite panels were tested by the rifle cartridges 7.62 x 51 mm FMJ M80. The high-speed camera was used to observe the impact of the missiles into the panel. As part of the evaluation of the experiment, the damage ranges of these panels were identified. The composite panel made of Twaron CT 747 TH110 impregnated with thermoplastic resin absorbed more energy of the impacting missiles than the panel made of Twaron CT 747 impregnated with thermoset resin. The results show that the panel made of Twaron CT 747 TH110 impregnated with thermoplastic resin, which was composed of 90 layers was not penetrated by the missile 7.62 mm M80 and complies with NATO AEP-55 STANAG 4569, protection level 1.
David Kusmič, Lenka Klakurková, Martin Julis, Pavel Gejdoš, Jindrich Vilis, and Ondrej Cech
The Electrochemical Society
In this paper, commercially cold-rolled and artificial aged EN AW 7075 T6 alloy has been used. To ensure increased corrosion resistance, surface hardness, scratching resistance, and aesthetic features, this aluminium alloy was subsequently hard anodised and hot-water sealed (AC-A). The hard anodizing and sealing process increased surface hardness up to 304±13 HV 1 from an initial surface hardness of 194±3 HV 1. Also, the microhardness of the anodised layer and bulk material has been documented. Scanning electron microscopy (SEM) was used for microstructure and trapped precipitates investigation in the 42.9±1.4 thick formed anodised layer investigation. The T6 treated (AC) and hard anodised together with sealed (AC-A) EN AW 7075 alloy corrosion properties were evaluated using the anodic potentiodynamic polarisation tests (PPT) in a neutral 2.5% NaCl deaerated solution. The corrosion rate CR (mm/y) decreased approx. 39-times for the hard anodised and sealed EN AW 7075 alloy (AC-A), associated with the shift of the Ecorr (mV) to more positive values, degreased Icorr (µA) and increased Rp (Ohm) values compared to the artificial aged (AC) alloy. Additionally, the pitting was evaluated using laser confocal microscopy, and the pitting coefficient was also calculated.