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Ballistic-Proof Concretes
Koutný, Ondřej ; Bílek,, Vlastimil (referee) ; Keršner, Zbyněk (referee) ; Ptáček, Petr (advisor)
Doctoral thesis „Ballistic-proof concretes“ deals with description, design and development of material based on ultra-high performance fibre reinforced cementitious composite with increased ballistic resistance i.e. increased resistance against high-strain rate dynamic loading induced by interaction of high-velocity moving objects. High mechanical properties, essential for such a material, are reached especially by maximal reduction of water-to-binder coefficient using high-range water reducing agents, high-strength aggregates and dense structure by precise selection and dosage of raw materials in the recipe. The main goal is to prepare a methodology for design of such a materials, observation of material behaviour on ballistic loading and quantitative description of material response for protective structures design. Properties of designed materials within this thesis are comparing with properties of commercially available and commonly used cementitious composites in order to create a concept for material limits in the field of ballistic protection. This concept enables to estimate ballistic protection of present or newly-designed materials and structures.
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Light ceramic materials for ballistic protection
Greguš, Peter ; Pouchlý, Václav (referee) ; Salamon, David (advisor)
This thesis gives a comprehensive characterization of lightweight non-oxide ceramic materials for ballistic applications, an overview of production technologies and processing of boron carbide B4C and its ceramic-based composites. A framework for evaluating the ballistic resistance of the material based on mechanical properties is shown there. It can be used in experiments without normalized equipment. The experiments including B4C + Si, B4C + Ti composites, and application of Spark plasma sintering (SPS) were designed according to outputs from the theoretical part. The volume fractions of Si, Ti dopants were optimized based on ongoing chemical reactions during sintering. The obtained samples were subjects of mechanical testing which results were compared to identify the ideal ratio of matrix and reinforcement. As the best suited material for ballistic protection, B4C + 1,0 obj. % reaches these values of parameters; hardness = 3502 ± 122 HV1; fracture toughness KIC = 2,97 ± 0,03 MPam^0,5.
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Possibilities of using cold gas dynamic spray (Cold Spray) in military applications
Dvořáček, Jan ; Štěpánek, Roman (referee) ; Řehořek, Lukáš (advisor)
This work aims to acquaint with thermal spray method called Cold spray. This method is used for repair of expensive and badly replaceable components, which are mainly used in aerospace and military branch of industry. These repairs cause economic savings, higher accuracy and quality than other thermal spray methods. There is a possibility to use Cold spray for ballistic armor production. It is possible that ballistic protection would have higher ballistic efficiency, durability and coherence. The second part of the work handle with the evaluation of the interface of a metal-ceramic two-layer ballistic protection system made by the cold spray method. The evaluation was performed in the form of light and electron microscopy.
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Influencing the hydration of high-performance composites using zinc ions
Všetečka, Tomáš ; Hajzler, Jan (referee) ; Novotný, Radoslav (advisor)
The bachelor thesis is focused on the influence of hydration of high-performance cementitious composites, more specifically reactive powder composites. Zinc ions were supplied by the compounds of zinc oxide and zinc sulphate heptahydrate. Zinc ions were added by weight content to cement at concentrations of 0.2; 0.5 and 1.0 wt. %. The development of properties depending on the content of zinc ions and the type of compound used was monitored in this work. The measured values were compared with reference values that did not contain zinc ions. The highest compressive strengths were obtained with a sample containing 1.0% Zn in the form of zinc oxide. However, this sample is associated with a longer setting time due to the retarding effect of zinc ions on hydration. The retardation effect was monitored using isothermal calorimetry. For samples containing zinc ions, a negative effect on the brass layer of steel fibers, which was used as reinforcement, was observed. Due to the addition of zinc ions, dezincification and subsequent removal of brass from the surface of the fibers took place. Therefore, these specimens had lower tensile strengths. A positive effect on the differential ballistic protection efficiency factor was observed for a sample containing 1% Zn in the form of zinc oxide.
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Manufacturing of composite for ballistic purposes
Majchrák, Aleš ; Gregor, Lukáš (referee) ; Zouhar, Jan (advisor)
The master thesis deals with high-strength fiber composites with a focus on their use in ballistic protection. It’s aim is to manufacture of composite panels and to test their properties. The theoretical part discusses the fiber composites area and ballistic protection. The experimental part consists of the choice of the suitable technologies for the production of the panels of the given materials, the production process itself, the preparation of the samples and their testing. Materials used for production were Twaron from aramides group and Endumax from the UHMWPE group of materials. Panels had three different matrices – epoxide resine, thermoset matrix and thermoplastic matrix. Manufacturing methods consisted of vacuum infusion, hot press and autoclave. Tensile and bending tests were examined, so as ballistic tests on the Taylor anvil test device and in ballistic laboratory. The results confirmed the high strenght of the material and its ability to absorb kinetic energy. During ballistic tests, the amount of material resistence against the ballistic impact was observed with regard to the NIJ 0101.06 standard and the limit thickness within tested samples was defined.
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Reactive powder concretes (RPC) with redispersible polymer powders
Ondrůšková, Nela ; Másilko, Jiří (referee) ; Šoukal, František (advisor)
The thesis entitled "Reactive Powder Concretes (RPC) with Redispersible Powder Polymers" deals with the description, design and development of a material with increased ballistic resistance, i.e. with increased resistance to high-speed dynamic stresses due to interaction with a projectile. The high mechanical properties of RPC are achieved mainly by reducing the water coefficient, using a large dose of superplasticizers and high strength aggregates to achieve the densest possible structure. The aim of this work is to investigate the effect of addition of redispersible powder polymer to RPC composite and to find the optimum type and amount of polymer to form a co-matrix, thus improving material properties such as flexural tensile strength and toughness. The preparation, procedure and processing of each formulation are described in each chapter, and the properties of these materials and observations of their behaviour under ballistic loading are described. Experimentally, the thesis focused on monitoring the effect of polymer type and amount, particularly on the change in bulk density and on compressive and flexural tensile strength. The results obtained for the different formulations were compared with each other and related to a reference. SEM analysis was performed to monitor the polymer film formation in the matrix. Based on the tests, two formulations with the best comprehensive properties were selected. These two formulations were subjected to DOP ballistic test.
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Influencing the hydration of high-performance composites using zinc ions
Všetečka, Tomáš ; Hajzler, Jan (referee) ; Novotný, Radoslav (advisor)
The bachelor thesis is focused on the influence of hydration of high-performance cementitious composites, more specifically reactive powder composites. Zinc ions were supplied by the compounds of zinc oxide and zinc sulphate heptahydrate. Zinc ions were added by weight content to cement at concentrations of 0.2; 0.5 and 1.0 wt. %. The development of properties depending on the content of zinc ions and the type of compound used was monitored in this work. The measured values were compared with reference values that did not contain zinc ions. The highest compressive strengths were obtained with a sample containing 1.0% Zn in the form of zinc oxide. However, this sample is associated with a longer setting time due to the retarding effect of zinc ions on hydration. The retardation effect was monitored using isothermal calorimetry. For samples containing zinc ions, a negative effect on the brass layer of steel fibers, which was used as reinforcement, was observed. Due to the addition of zinc ions, dezincification and subsequent removal of brass from the surface of the fibers took place. Therefore, these specimens had lower tensile strengths. A positive effect on the differential ballistic protection efficiency factor was observed for a sample containing 1% Zn in the form of zinc oxide.
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Effect of shooting stances on ballistic protection of the shooter
Zdražila, Václav ; Barták, Erik (advisor) ; Kubový, Petr (referee)
Title Effect of shooting stances on ballistic protection of the shooter Objectives The goal of this thesis is to develop a method which could measure ballistic protection, which is currently provided by a bulletproof vest to the shooter in a current shooting stance. This work also focuses on analysis of the currently used shooting techniques and shooting stances, comparison of protection they can provide, and last but not least, to fill the gap in literature, wich deals with this issue. Methods This is an empirical thesis of observational character. Shooting stances were tested on a camera system named Qualisys. The results were first processed by a program for 3D analysis, and the ballistic protection provided by the bulletproof vest in different positions was calculated in a program for 3D modeling. Results: From the measured data, it was found that changing targets to the left (for right- handed) the provided ballistic protection significantly changes to worse. Conversely, when changing targets to the right, the ballistic protection faired the same or slightly better than aiming forward. The worst results of all stances came from the side shooting stance in which the bulletproof vest provided almost no protection. Keywords Ballistic protection, shooting stances, Qualisys, 3d analysis, vital zone
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Possibilities of using cold gas dynamic spray (Cold Spray) in military applications
Dvořáček, Jan ; Štěpánek, Roman (referee) ; Řehořek, Lukáš (advisor)
This work aims to acquaint with thermal spray method called Cold spray. This method is used for repair of expensive and badly replaceable components, which are mainly used in aerospace and military branch of industry. These repairs cause economic savings, higher accuracy and quality than other thermal spray methods. There is a possibility to use Cold spray for ballistic armor production. It is possible that ballistic protection would have higher ballistic efficiency, durability and coherence. The second part of the work handle with the evaluation of the interface of a metal-ceramic two-layer ballistic protection system made by the cold spray method. The evaluation was performed in the form of light and electron microscopy.
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Light ceramic materials for ballistic protection
Greguš, Peter ; Pouchlý, Václav (referee) ; Salamon, David (advisor)
This thesis gives a comprehensive characterization of lightweight non-oxide ceramic materials for ballistic applications, an overview of production technologies and processing of boron carbide B4C and its ceramic-based composites. A framework for evaluating the ballistic resistance of the material based on mechanical properties is shown there. It can be used in experiments without normalized equipment. The experiments including B4C + Si, B4C + Ti composites, and application of Spark plasma sintering (SPS) were designed according to outputs from the theoretical part. The volume fractions of Si, Ti dopants were optimized based on ongoing chemical reactions during sintering. The obtained samples were subjects of mechanical testing which results were compared to identify the ideal ratio of matrix and reinforcement. As the best suited material for ballistic protection, B4C + 1,0 obj. % reaches these values of parameters; hardness = 3502 ± 122 HV1; fracture toughness KIC = 2,97 ± 0,03 MPam^0,5.
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