Carbon fiber (CF) must be protected from thermal oxidation for high temperature application because of its low thermo-oxidative stability above 450°C in air. CF is now increasingly being used as a reinforcing material in the construction industry. A thermal and oxidation resistant coating is necessary for CF-reinforced concrete (CFRC) composites in order to satisfy a high level of safety standard in the case of fire. New types of pre-ceramic coatings, such as Tyranno® polymer (Si–Ti based pre-ceramic) and SiO₂ sol–gel, have been deposited on CF filament yarn by means of a wet chemical continuous dip coating method. The results of surface analyses, e.g. scanning electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy, showed the changes in topographical properties of CF caused by the coatings. Thermogravimetric analysis proved that the high temperature (up to 800°C) oxidation stability of CF was considerably improved due to the coatings. Tensile test results indicated that the strength of CF yarn at 20°C was increased by up to 80% with the coatings. Thermo-mechanical properties were also enhanced up to 600°C. CF yarn retains its original strength and elasticity modulus, i.e. the stiffness at 700°C, with a Tyranno® polymer coating.

This contribution will introduce carbon-reinforced concrete components (so-called carbon concrete composites, or C³) with sensor functionalities for innovative building envelopes. For a continuous in situ structural monitoring, these textile-reinforced concrete components are equipped with textile sensor networks consisting of resistive carbon fiber sensors (CFSs), which are integrated into the carbon fiber non-crimp fabrics of the concrete reinforcement by multiaxial warp-knitting. The in situ CFSs, consisting of 1 k or 50 k carbon fiber roving with added staple fiber/multifilament dielectric cladding, are later integral to the load-distributing elements of the concrete component, and elongations within these are easy to record with good correlation to ohmic resistance changes. Gage factors of k = 0.52–1.23 at linearity deviations of ALin=4.0–8.7% are feasible. This allows a monitoring of C³ building envelopes for structural mechanical changes caused by physical changes within the component through mechanical or thermal loads or deformation and cracks.

Fiber-reinforced plastics for industrial applications face constantly increasing demands regarding efficiency, reliability, and economy. Furthermore, it was shown that fiber-reinforced plastics with tailored reinforcements are superior to metallic or monolithic materials. However, a trustworthy description of the load-specific failure behavior and damage evolution of composite structures can hardly be given, because these processes are very complex and are still not entirely understood. Among other things, several research groups have shown that material damages like fiber fracture, delamination, matrix cracking, or flaws can be discovered by analyzing the electrical properties of conductive composites, for example, carbon fiber–reinforced plastics. Furthermore, it was shown that this method could be used for structural health monitoring or nondestructive evaluation. Within this study, magnetic induction tomography, which is a new imaging approach, is introduced in the topic of nondestructive evaluation of carbon fiber–reinforced plastics. This non-contacting imaging method gains the inner spatial distribution of conductivity of a specimen and depicts material inhomogeneity, like damages, not only in two-dimensional images but also in three-dimensional images. Numerical and experimental investigations are presented, which give a first impression of the performance of this technique. It is demonstrated that magnetic induction tomography is a promising approach for nondestructive evaluation. Potentially, it can be used for fabrication quality control of conductive fiber–reinforced plastics and as a structural health monitoring system using an integrated or superficially applied magnetic induction tomography setup.

Une interphase fibre de carbone/matrice époxy thermiquement auto-réparable a été construite sur la base de liaisons covalentes Diels-Alder (D-A) thermiquement réversibles. L’interphase modifiée par D-A a été formée en greffant des groupes maléimide sur la surface de la fibre de carbone et en introduisant des groupes furane dans le réseau polyépoxy. La capacité d’auto-réparation interfaciale a été caractérisée par le test de déchaussement de la micro-goutte. La surface de la fibre de carbone a subi un traitement en trois étapes : (i) oxydation par l’acide nitrique, (ii) amination par la tétraéthylènepentamine (TEPA) et (iii) greffage de bismaléimide (BMI). Après chaque étape de traitement, les modifications physico-chimiques de surfaces de la fibre ont été caractérisées par microscopies (MEB et AFM) et par spectroscopies (XPS, et ATR-FTIR). La modification de la matrice a été effectuée en copolymérisant le furfuryl glycidyl éther (FGE) au réseau époxy/amine et les propriétés de la matrice ont été évaluées par TGA, DSC, ATR-FTIR, et traction uniaxiale. Le caractère réversible des liaisons Diels-Alder a été également vérifié par DSC, TGA et RMN. Pour caractériser les capacités d'auto-réparation de l’interphase modifiée par D-A, les propriétés mécaniques et les capacités d'auto-réparation de l'interphase construite en combinant la matrice DGEBA-FGE/amine avec une série de fibres de carbone greffés par BMI ont été mesurées en fonction du temps d’oxydation préalable au greffage (gouvernant la réactivité de la fibre de carbone). Enfin, car le FGE joue un double rôle dans le système interfacial modifié par D-A, à la fois dans l’architecture en intervenant comme allongeur de chaîne entre nœuds de réticulation du réseau époxyde et au niveau de l’interphase en contribuant dans la formation des liaisons réversibles, l'influence de la concentration de FGE dans la matrice a été étudiée sur les propriétés mécaniques de l'interphase et également sur les propriétés mécaniques de la matrice. Par conséquent, ce travail a permis d’aboutir à la procédure optimale pour construire une interphase fibre de carbone/époxy thermiquement auto-réparable basée sur des liaisons covalentes Diels-Alder (thermo réversibles). L'interphase ainsi formée possède non seulement des capacités d’auto-réparations multiples, mais également des propriétés mécaniques compatibles avec une approche ‘matériau composite’. En effet, les propriétés mécaniques globales des matériaux composites, comme attendu, sont dépendantes des caractéristiques de cette interphase mais ne seront pas réduites par la présence de celle-ci notamment pour assurer la durabilité du matériau composite. / A thermally self-healable carbon/epoxy interphase was designed based on Diels-Alder (D-A) thermally reversible covalent bonds. The D-A modified interphase was formed between maleimide groups grafted on carbon fiber surface and furan groups introduced into epoxy network. The self-healing ability was characterized by a micromechanical approach using the micro-droplet debonding test. In this work, carbon fiber surface underwent a three-step treatment to graft maleimide groups, including HNO3 oxidization, tetraethylenepentamine (TEPA) amination, and bismaleimide (BMI) grafting. The fiber surface physico-chemical modifications after each treatment step were characterized by microscopies (SEM, and AFM) and spectroscopies (XPS, and ATR-FTIR). The matrix modification was carried on mixing furfuryl glycidyl ether (FGE) into epoxy/amine network and the properties of modified matrix were studied by TGA, DSC, ATR-FTIR, and tensile tests. The reversible character of Diels-Alder bond was also followed by DSC, TGA, and NMR. The interfacial mechanical properties and the self-healing abilities of the D-A modified interphases, built by combining DGEBA-FGE/amine matrix with a serial of BMI-grafted carbon fibers tuned as a function of the oxidization time were investigated. At last, since FGE plays a double-role in D-A modified interfacial system, i.e. chain extender in epoxy network and self-healing agent in the interphase, the influences of FGE content in matrix on the mechanical properties of interphase and also on the mechanical properties of cured matrix were evaluated. As a consequence, this study allowed to achieve the best process to build a thermally self-healable carbon/epoxy interphase based on thermally reversible Diels-Alder covalent bonds. The formed interphase has not only the successive self-healable abilities but also the required mechanical properties. Additionally, the overall mechanical properties of the composite material based on this interphase will not be weakened significantly after the interfacial modifications.

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Saab Kockums har på länge tillämpat kompositmaterial i uppbyggande av deras nya fartyg. Detta medför många fördelar kopplat till stealth teknik men samtidigt utgör vissa andra utmaningar gällande installationer ombord. Arbetet utfördes därför med syfte att undersöka möjligheten för användning av lastskenor för standardiserat montage på dessa fartyg. Vidare skulle det utvecklas en standardlösning för montaget där användarvänlighet står som fokus.   Arbetet inleds med en undersökning av produkter från marknaden där också utvecklingspotential identifierades. Fokus med undersökningen var att hitta den optimala utseende för montaget. Dessa punkter användes därefter för att generera idéer för samtliga delar. Den bästa idéen filtreras fram genom poängsättning kopplat till utsatta kravställningen. För infästning av konstruktion bestämdes det med hjälp av olika litteraturstudier tillsammans med dragprovsdata som tillhandahålls av Kockums. Litteraturstudien omfattades studie på egenskaper hos sandwichkonstruktioner samt dragproven på olika lastfallen som utfördes på andra rapporter. Sist verifierades konceptet utifrån olika aspekter baserat på olika sätt. Hållfasthetmässigt är baserade på FEM/manuella beräkningar, tillverkning är baserade på intervju och monteringen baserad på 3D-utskrift.   En konstruktion på montaget erhölls som resultatet av arbetet där den klarade samtliga krav som ställdes. Konstruktionen består av förmonterade skena som har ett homogen utseende tillsammans med vinkelbeslag för montering av eventuella bäddar eller dämpare. Konstruktionen fästs på skottet med M8 blindnitsmuttrar för områden utan stötkrav och M10 muttrar tillsammans med laminatsförstärkning för områden med stötkrav. Som bevisat är det möjligt att tillverka dessa med några enkla steg av standardprofiler från marknaden. Det är även enkelt att montera ombord på fartygen. / Saab Kockums has long time used composite materials in the construction of their new ships. This brings many advantages linked to stealth technology, but at the same time poses some other challenges regarding installations on board. This thesis was therefore performed with the aim of investigating the possibility of using cargo rails for standardized assembly on these ships. Furthermore, a developed standard solution for assembly where ease of use is the focus for this study.  The work begins with an analysis of products from the market and potential development is identified. The focus of the investigation was to find the optimal design for the montage. These potentials were then used to generate ideas for parts in the design. The best idea is filtered through scoring linked to the set of requirements. For attachment of the construction, it was determined with the help of various literature studies along with tensile test data provided by Kockums. The literature study included studies on properties of sandwich constructions as well as tensile tests on different load cases that were carried out on other reports. Finally, the concept is verified based on different aspects. The durability is based on FEM/manual calculations, the manufacturing is based on interview and finally the assembly is based on 3D printing.  A construction of the assembly was obtained as the result of the work and met all the requirements that were set. The construction consists of pre-assembled cargo rails that have a homogeneous appearance together with angle fittings for mounting any foundations or dampers. The structure shall be attached to the bulkhead with M8 blind rivet nuts for areas without impact requirements and M10 nuts together with laminate reinforcement for areas with impact requirements. As proven, it is possible to manufacture these in a few simple steps from standard profiles from the market and easily fit on board the ships.

[pt] O presente trabalho tem como objetivo analisar a utilização de barras constituídas por material compósito para atuarem como reforço de vigas de concreto submetidas à flexão. As barras analisadas são constituídas por polímero reforçado com fibras de carbono (PRFC), material este que apresenta comportamento linear elástico até a ruptura. Este material possui algumas vantagens em relação ao aço, como por exemplo, resistência à tração consideravelmente superior além de não ser suscetível ao fenômeno da corrosão ocasionada por intempéries ambientais. Durante o desenvolvimento do trabalho foi obtido um artigo o qual demonstra resultados de ensaios de laboratório nos quais os autores utilizaram vigas de concreto submetidas a ensaio de flexão por quatro pontos e reforçadas com barras de PRFC. Neste trabalho, o mesmo ensaio foi simulado no software Atena, programa este que realiza análise não linear para estruturas de concreto, considerando a fissuração deste material. Os resultados obtidos pelo software apresentaram consistência com os resultados registrados em laboratório pelos autores. Foi ainda analisada uma viga contínua de concreto submetida a um carregamento uniformemente distribuído. Essa viga foi reforçada com barras de mesmo diâmetro alterando-se apenas o material dessas barras (aço e PRFC). Dessa maneira, foi analisado o valor de carregamento que ocasiona a ruptura da viga. Foram constatadas duas importantes desvantagens das barras de PRFC em relação ao aço. A primeira desvantagem está no custo superior ao aço e por apresentar comportamento elástico até o rompimento, o PRFC não confere à estrutura de concreto uma ruptura dúctil. Os objetivos deste trabalho foram cumpridos e ao final são propostos novos estudos a serem realizados sobre o tema. / [en] The aim of the present work is to analyze the use of bars made of composite material to act as reinforcement for concrete beams subjected to bending. The analyzed bars are constituted by polymer reinforced with carbon fibers (PRFC), a material that presents linear elastic behavior until rupture. This material has some advantages in relation to steel, such as considerably higher tensile strength in addition to not being susceptible to the phenomenon of corrosion caused by environmental conditions. During the development of the work, an article was obtained which demonstrates results of laboratory tests in which the authors used concrete beams subjected to flexion testing by four points and reinforced with PRFC bars. In this work, the same test was simulated in the Atena software, a program that performs non-linear analysis for concrete structures, considering the cracking of this material. The results obtained by the software were consistent with the results recorded in the laboratory by the authors. It was also analyzed a continuous concrete beam subjected to a uniformly distributed load. This beam was reinforced with bars of the same diameter, changing only the material of these bars (steel and PRFC. In this way, the loading value that causes the beam to break when it is reinforced with steel bars and when it is reinforced with PRFC bars of the same diameter was analyzed. Two important disadvantages of PRFC bars in relation to steel have been noted. Due to its elastic behavior until breaking, this composite material does not give the concrete structure a ductile rupture. In addition, its cost is considerably higher than steel bars, since no suppliers of this type of reinforcement have been identified in Brazil, thus increasing the cost to purchase this product. The objectives of this work were accomplished and, in the end, new studies are proposed to be carried out on the theme.

The launch environment experiences many vibration, shock, and acoustic loads. A great concern is the high random vibration levels that can damage components and spacecraft structures, which can cause a mission failure. An effective method of reducing high frequency energy is using isolators. Overall, the need for vibration isolation has been increasing because there has been an increase in the use of mechanisms in which vibrations are prevalent. In addition, there has not been extensive research on the effects of isolators that are outgassed and cured. Therefore, it is important to investigate and understand the vibrational effects on isolators. It is convenient to outgas and cure isolators for the benefit of some components because that eliminates contamination, but outgassing and bake-out could potentially affect the frequency response of the isolator system in a negative way. It is valuable to investigate how much outgassing and bake-out might affect the performance, if any, of the vibration isolator in order to benefit companies who may need that kind of information. The vibration isolators used for the purpose of this research were twenty E22-02-40 isolators provided by Barry Controls, a Hutchinson Group Company. The E22-02-40 isolators were outgassed and cured (heated at high temperatures) in order to be turned from grade C into grade A level for outgassing. Then the vibrational performance of those isolators were tested and compared to the isolators that were not outgassed and not cured. Vibration tests were run in the flat frequency spectrum and high frequency spectrum. The maximum percent difference occurred in the grade A level isolators, in which the first frequency mode increased by 33.3 % in the z direction from the grade C isolators. A numerical finite element analysis was performed on Abaqus/CAE in order to verify the experimental results. In addition, a swelling test was conducted on the isolators to test their physical characteristics change after they were outgassed and cured.

Исследовать материалы, используемые для усиления железобетонных балок, провести расчеты усиления балки в направлении действия изгибающего момента и поперечной силы с использованием композитных материалов с их технико-экономическим обоснованием. / Investigate the materials used to reinforce reinforced concrete beams, carry out calculations of the beam reinforcement in the direction of the bending moment and shear force using composite materials with their feasibility study.