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## Synthesis and properties of magnetorheological fluids and their possible application in protective armours

### Joanna Kozłowska

#### Abstract

Modern body armour design comprises a group of high-strength materials in a form of textiles made from para-aramid, polyethylene UHWPE and PBO fibers, polymer composites or ceramic and metallic inserts. Selection of an applicable material and the form of its structure are preliminary factors determining the construction of the protective armours. The current line of research, in the design of modern personal protection armours, refers to the actions of increasing the resistance of body armour, while optimizing the mass of the system, providing multifunctional characteristics (resistance to various types of risks) as well as, increasing their ergonomics. One method of obtaining these characteristics is the introduction of a structural component, such as controllable liquid, shear thickening fluids (STF), coating para-aramid fibers of textile. Numerous studies in this area indicate the possibility of increasing the energy dissipation capacity of the system during the impact of a projectile and giving them protective properties against edged weapons. Simultaneously, the added value of STF containing systems, compared to the conventional armour, is increased flexibility and the possibility of reducing the number of layers of ballistic fabric. In the light of these reports, in this study innovative attempts were undertaken to implement magnetorheological (MR) fluid, controlled by the magnetic field, into the protective armor systems and the evaluation of their ballistic performance and stab resistance. The scope of this dissertation refers to the fabrication and characterization of MR fluid and the evaluation of their possibility of use in a flexible protective armour. A series of MR fluids, of different compositions, based on synthetic oils, with carbonyl iron particles, were produced. An attempt was made to obtain optimal properties of the MR fluid through the knowledge of the correlation between the type of carbonyl iron particles, carrier oil viscosity and the type of a stabilizer, and achieved practical characteristics. The produced fluids were been used in composite structures of protective armor with high-strength materials, in the form of para-aramid fabrics and non-woven polyethylene fibers. Four methods of MR fluid implementation, in high-strength structures materials, were employed: impregnating fabrics, polyurethane foam, polyethylene bags and elastomeric samples filled with fluids. In the theoretical part of the dissertation, fundamentals of rheology, the current state of the art on the composition, properties and applications of MR fluids, and the available knowledge on the use of new materials in armours structure, necessary to comprehend the subject of analyzed materials, were presented The hypothesis that the use of magnetorheological fluid in the structure of flexible armor will increase their protective performance in the area of bullet and stab-resistance, under a magnetic field, was formulated. The scope of the research work was divided into two parts. The first part presents the results of rheological and magnetic measurements, sedimentation observations, and cytotoxicity of produced magnetorheological fluids. The second part of the realized work is focused on manufactured, composite structures with magnetorheological fluids, based on high-strength, ballistic materials and evaluating their stab and ballistic resistance. On the basis of obtained results, it was found that the process of magnetorheological fluid implementation has a significant impact on the composite ballistic armor performance. It was found that the samples containing magnetorheological fluids in polyethylene bags, demonstrate improvement in protective performance of composites structures. Moreover, reduction in ballistic deformation, for samples on the basis of para-aramid fabric, after impregnation of magnetorheological fluids, was observed. From one side, the composites containing magnetorheological fluids are characterized by high areal density of targets. From the other side, implementation of the MR components to structure of the high-strength ballistic materials ensures target thickness reductions, can enhance energy absorbing process, and be applicable in reducing trauma blunt effect.
Record ID
WUT31a7f3b0d15848c0bb22d1ed37d10d44
Diploma type
Doctor of Philosophy
Author
Title in Polish
Otrzymywanie i właściwości cieczy magnetoreologicznych pod kątem ich zastosowań w pancerzach ochronnych
Title in English
Synthesis and properties of magnetorheological fluids and their possible application in protective armours
Language
(pl) Polish
Certifying Unit
Faculty of Materials Science and Engineering (FMSE)
Discipline
material sciences and engineering / (technology domain) / (technological sciences)
Status
Finished
Start date
29-06-2012
Defense Date
23-05-2014
Title date
23-05-2014
Supervisor
Pages
139
Keywords in English
xxx
Abstract in English
Modern body armour design comprises a group of high-strength materials in a form of textiles made from para-aramid, polyethylene UHWPE and PBO fibers, polymer composites or ceramic and metallic inserts. Selection of an applicable material and the form of its structure are preliminary factors determining the construction of the protective armours. The current line of research, in the design of modern personal protection armours, refers to the actions of increasing the resistance of body armour, while optimizing the mass of the system, providing multifunctional characteristics (resistance to various types of risks) as well as, increasing their ergonomics. One method of obtaining these characteristics is the introduction of a structural component, such as controllable liquid, shear thickening fluids (STF), coating para-aramid fibers of textile. Numerous studies in this area indicate the possibility of increasing the energy dissipation capacity of the system during the impact of a projectile and giving them protective properties against edged weapons. Simultaneously, the added value of STF containing systems, compared to the conventional armour, is increased flexibility and the possibility of reducing the number of layers of ballistic fabric. In the light of these reports, in this study innovative attempts were undertaken to implement magnetorheological (MR) fluid, controlled by the magnetic field, into the protective armor systems and the evaluation of their ballistic performance and stab resistance. The scope of this dissertation refers to the fabrication and characterization of MR fluid and the evaluation of their possibility of use in a flexible protective armour. A series of MR fluids, of different compositions, based on synthetic oils, with carbonyl iron particles, were produced. An attempt was made to obtain optimal properties of the MR fluid through the knowledge of the correlation between the type of carbonyl iron particles, carrier oil viscosity and the type of a stabilizer, and achieved practical characteristics. The produced fluids were been used in composite structures of protective armor with high-strength materials, in the form of para-aramid fabrics and non-woven polyethylene fibers. Four methods of MR fluid implementation, in high-strength structures materials, were employed: impregnating fabrics, polyurethane foam, polyethylene bags and elastomeric samples filled with fluids. In the theoretical part of the dissertation, fundamentals of rheology, the current state of the art on the composition, properties and applications of MR fluids, and the available knowledge on the use of new materials in armours structure, necessary to comprehend the subject of analyzed materials, were presented The hypothesis that the use of magnetorheological fluid in the structure of flexible armor will increase their protective performance in the area of bullet and stab-resistance, under a magnetic field, was formulated. The scope of the research work was divided into two parts. The first part presents the results of rheological and magnetic measurements, sedimentation observations, and cytotoxicity of produced magnetorheological fluids. The second part of the realized work is focused on manufactured, composite structures with magnetorheological fluids, based on high-strength, ballistic materials and evaluating their stab and ballistic resistance. On the basis of obtained results, it was found that the process of magnetorheological fluid implementation has a significant impact on the composite ballistic armor performance. It was found that the samples containing magnetorheological fluids in polyethylene bags, demonstrate improvement in protective performance of composites structures. Moreover, reduction in ballistic deformation, for samples on the basis of para-aramid fabric, after impregnation of magnetorheological fluids, was observed. From one side, the composites containing magnetorheological fluids are characterized by high areal density of targets. From the other side, implementation of the MR components to structure of the high-strength ballistic materials ensures target thickness reductions, can enhance energy absorbing process, and be applicable in reducing trauma blunt effect.
Thesis file
• File: 1
Kozlowska.pdf
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Uniform Resource Identifier
https://repo.pw.edu.pl/info/phd/WUT31a7f3b0d15848c0bb22d1ed37d10d44/
URN
urn:pw-repo:WUT31a7f3b0d15848c0bb22d1ed37d10d44

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