The natural hip joint in healthy people has a very low friction with very little (or no) wear. It works as a dynamically loaded bearing and is subjected to about 1-2 million cycles of loading per year. The applied load is the body weight which is tripled when walking and even higher during other activities such as running and jumping. Unfortunately these joints are not always healthy due to various causes such as fractures or disease leading to severe pain which necessitates joint replacement. Currently, the orthopaedic industries are working towards developing an ideal artificial hip joint with low wear, low friction, good lubrication, better fixation/stability and biocompatibility. Many different designs and materials have been investigated with some promising new implants which can be used depending on patients' individual need (large or small joint), activity and age. In this work, two types of artificial hip joints were tested for friction and lubrication studies: Metal-on-Metal (MoM) Biomet hip resurfacing ReCaps with large diameters (>35-60 mm) and different diametral clearances (~ 60-350 µm), and Zirconia Toughened Alumina (ZTA) heads against carbon-fibre-reinforced poly-ether-ether ketone (CFR PEEK) cups with different diameters (>35-60 mm) and diametral clearances (60-1860 µm). Seven serum-based lubricants with different viscosities were used with and without carboxy methyl cellulose (CMC) additions as gelling agent to increase viscosity depending on the CMC content. The maximum load applied was 2000 N for the stance phase with a minimum load of 100 N for the swing phase. A Pro-Sim friction hip simulator was used to investigate the frictional torque generated between the articulating surfaces so as the friction factor can be calculated. Stribeck analysis was then employed to assess the mode of lubrication. For the metal-on-metal hip resurfacing joints, the friction factors were in the range 0.03-0.151 and those for the ZTA ceramic heads versus CFR PEEK cups were in the range 0.006-0.32. Stribeck analyses showed mainly mixed lubrication for both MoM and ZTA ceramic-on-CFR PEEK joints. The experimental results were in agreement with most of the theoretical calculations suggesting mixed lubricating regimes at low viscosities and moving on to fluid film lubrication at higher viscosities. Joints with larger-diameters, lower clearances and lower surface roughness exhibited a higher lambda ratio suggesting improved lubrication. Viscosity flow curves for the serum-based lubricants having viscosity ≤ 0.00524 Pas showed non-linear relationship between viscosity and shear rate indicating non-Newtonian flow with pseudoplastic or shear-thinning characteristic, i.e. viscosity decreased as shear rate increased up to shear rates of ~ 1000 s⁻¹. However, at shear rates greater than 1000 s⁻¹ Newtonian flow became dominant with almost constant viscosity, i.e. a linear relationship between shear stress and shear rate. On the other hand, viscosity flow curves for the lubricants with viscosity ≥ 0.0128 Pas showed non-Newtonian behaviour up to a shear rate of 3000 s⁻¹ with shear-thinning characteristic.

A novel type of precast, prestressed concrete structural element is being implemented in load-bearing systems in buildings. These structural elements combine the use of high-performance, self-consolidating concrete (HPSCC) and non-corroding carbon fibre reinforced polymer (CFRP) prestressing tendons; this produces highly optimized, slender structural elements with excellent serviceability and (presumed) extended service lives. More widely, the use of new construction techniques, innovative materials, and ground-breaking designs is increasingly commonplace in today's rapidly evolving building construction industry. However, the performance of these and other structural elements in fire is in general not well known and must be understood before these can be used with confidence in load-bearing applications where structural fire resistance is a concern. Structural fire testing has traditionally relied on the use of the standard fire resistance test (i.e. furnace test) for assuring regulatory compliance of structural elements and assemblies, and in many cases also for developing the scientific understanding of structural response to fire. Conceived in the early 1900s and fundamentally unchanged since then, the standard testing procedure is characterized by its high cost and low repeatability. A novel test method, the Heat-Transfer Rate Inducing System (H-TRIS), resulting from a mental shift associated with controlling the thermal exposure not by temperature (e.g. temperature measured by thermocouples) but rather by the time-history of incident heat flux, was conceived, developed, and validated within the scope of the work presented in this thesis. H-TRIS allows for experimental studies to be carried out with high repeatability, imposing rationally quantifiable thermal exposure, all at low economic and temporal cost. The research presented in this thesis fundamentally seeks to examine and understand the behaviour of CFRP prestressed HPSCC structural elements in fire, with emphasis placed on undesired 'premature' failure mechanisms linked to the occurrence of heat-induced concrete spalling and/or loss of bond between the pretensioned CFRP tendons and the concrete. Results from fire resistance tests presented herein show that, although compliant with testing standards, temperature distributions inside furnaces (5 to 10% deviation) appear to influence the occurrence of heat-induced concrete spalling for specimens tested simultaneously during a single test; fair comparison of test results is therefore questionable if thermal exposure variability is not explicitly considered. In line with the aims of the research presented in this thesis, H-TRIS is used to carry out multiple comprehensive studies on the occurrence of concrete spalling and bond behaviour of CFRP tendons; imposing a quantified, reproducible and rational thermal exposure. Test results led to the conclusion that a "one size fits all" approach for mitigating the risk of heat-induced concrete spalling (e.g. prescribed dose of polypropylene (PP) fibres included in fresh concrete), appears to be ineffective and inappropriate in some of the conditions examined. This work demonstrates that PP fibre cross section and individual fibre length can have an influence on the risk of spalling for the HPSCC mixes tested herein. The testing presented herein has convincingly shown, for the first time using multiple repeated tests under tightly controlled thermal and mechanical conditions, that spalling depends not only on the thermal gradients in concrete during heating but also on the size and restraint conditions of the tested specimen. Furthermore, observations from large scale standard fire resistance tests showed that loss of bond strength of pretensioned CFRP tendons occurred at a 'critical' temperature of the tendons in the heated region, irrespective of the temperature of the tendons at the prestress transfer length, in unheated overhangs. This contradicts conventional wisdom for the structural fire safety design of concrete elements pretensioned with CFRP, in which a minimum unheated overhang is generally prescribed. Overall, the research studies presented in this thesis showed that a rational and practical understanding of the behaviour of CFRP prestressed HPSCC structural elements during real fires is unlikely to be achieved only by performing additional standard fire resistance tests. Hence, H-TRIS presents an opportunity to help promote an industry-wide move away from the contemporary pass/fail and costly furnace testing environment. Recommendations for further research to achieve the above goal are provided.

Neste trabalho propôs-se a construção de um tubo de material compósito híbrido, com fibra de vidro e fibra de carbono, para utilização como prolongador de prótese de membro inferior a serem fabricadas pela AACD - Associação de Assistência à Criança Deficiente. O objetivo é avaliar as solicitações da prótese para otimizar custo e reduzir a massa. Fez-se inicialmente um levantamento das propriedades dos materiais comerciais utilizados para a fabricação do prolongador para referenciar o desenvolvimento do componente da prótese. Utilizou-se modelagem por elementos finitos para otimizar o componente em função dos esforços biomecânicos a que a prótese é submetida. Nesta modelagem, estudaram-se várias disposições, quantidade e material das camadas de forma a atender às solicitações e minimizar os custos. O levantamento bibliográfico permitiu encontrar uma rota de menor custo para a fabricação de compósito que utiliza um processo de transferência de resina auxiliado a vácuo e pré-formados de vidro e carbono. Como referência, foi fabricado um componente pelo processo de bobinagem filamentar que produz materiais compósitos de qualidade reconhecida. O processo de moldagem por transferência de resina assistido à vácuo, apesar de ter alguns insumos importados, pela sua simplicidade pode ser realizado na própria AACD e se mostrou capaz de obter componentes com custo que viabiliza sua produção sem grandes investimentos em equipamentos. Apesar da redução de algumas das propriedades em relação à peça de referência, o tubo apresentou vantagens na redução de massa e na absorção de impacto. / In this work it was considered a construction of a pipe of hybrid composite material, with carbon and glass fibre, for use as prosthesis extension of inferior member to be manufactured for the Associação de Assistência à Criança Deficiente AACD. The objective is to evaluate the requests of prosthesis to optimize cost and to reduce weight. A survey of the properties of the commercial materials commonly used for the manufacture extension became initially a reference to the development of the final component. A finite element modeling was used to optimize the component in the biomechanics function related to the efforts which the prosthesis is submitted. In this modeling some disposals and numbers of layers, amount and material have been studied to take care of the requests and to minimize the cost. A bibliographical survey allowed finding a shipper route for the manufacture of composite that uses a process of vacuum assisted resin transfer molding and preforms of glass with carbon. As reference, a component was produced using filament winding process to compare the quality of the obtained composite pipe. The process, although to have some imported feed-stock, can be proper carried out by AACD and if it showed capable to produce components with cost that makes possible its production internally. Despite the reduction of some of the properties in relation to the reference part, the component presented advantages such as weight reduction and the impact absorption.

One major step needed for fusion to become a reliable energy source is the development of materials for the extreme conditions (high temperature, radioactivity and erosion) caused by hot plasmas. The main goal of the present study is to use and optimise ion beam methods (lateral resolution and sensitivity) to characterise the distribution of hydrogen isotopes that act as fuel. Materials from the test reactors JET (Joint European Torus), TEXTOR (Tokamak Experiment for Technology Oriented Research) and Tore Supra have been investigated. Deuterium, beryllium and carbon were measured by elastic recoil detection analysis (ERDA) and nuclear reaction analysis (NRA). To ensure high 3D spatial resolution a nuclear microbeam (spot size <10 µm) was used with 3He and 28Si beams. The release of hydrogen caused by the primary ion beam was monitored and accounted for. Large variations in surface (top 10 µm) deuterium concentrations in carbon fibre composites (CFC) from Tore Supra and TEXTOR was found, pointing out the importance of small pits and local fibre structure in understanding fuel retention. At deeper depths into the CFC limiter tiles from Tore Supra, deuterium rich bands were observed confirming the correlation between the internal material structure and fuel storage in the bulk. Sample cross sections from thick deposits on the JET divertor showed elemental distributions that were dominantly laminar although more complex structures also were observed. Depth profiles of this kind elucidate the plasma-wall interaction and material erosion/deposition processes in the reactor vessel. The information gained in this thesis will improve the knowledge of first wall material for the next generation fusion reactors, concerning the fuel retention and the lifetime of the plasma facing materials which is important for safety as well as economical reasons.

Für die elektrochemische Mikrobearbeitung superharter Werkstoffe, die Herstellung von faserbasierten Sensoren und die komplexe Funktionalisierung von faserverstärkten, polymeren Verbundwerkstoffen werden endlose Kohlenstoffeinzelfasern benötigt. Kohlenstofffasern werden in den jeweiligen Herstellungsprozessen (PAN und Pech) immer nur im Bündel gefertigt und angeboten. Einzelne Kohlenstofffasern sind nicht verfügbar. Für die Vereinzelung von Kohlenstofffasern aus dem Bündel wurden verschiedene Verfahren voruntersucht. Anschließend wurde auf Basis der Verfahren mit dem höchsten Vereinzelungspotenzial eine Vereinzelungsanlage aufgebaut. Die ersten Untersuchungen mit Hilfe der Vereinzelungsanlage zielten auf die Teilung von Faserbündeln als Vorstufe zu einer Einzelfaser ab. Die kontinuierliche Teilung von Bündeln konnte auf diese Weise erfolgreich durchgeführt werden. Die weitere Teilung halbierter Bündel wird aktuell untersucht. Halbierte Bündel können bereits in textilen Prozessen weiterverarbeitet oder für die Beschichtung genutzt werden. Auf diese Weise ist es möglich die Garnfeinheit der Rovings zu verringern und feinere Rovings als derzeit am Markt verfügbar anzubieten.

This thesis is a part of a larger project that focuses on the development of a highspeed, high energy flywheel using both high-tech composites and levitating magneticbearings alongside a custom made, permanent magnetized generator built into theflywheel itself. The goal of the project is then to integrate this flywheel into anelectrical vehicle.The main focus of this thesis is the composite material. The composite is to be usedas a shell around the flywheel rotor. This composite shell fills two purposes. The firstis to act as the main energy carrying material, storing above 75% of the total energy inthe flywheel. The second purpose it to strengthen the machine, holding it together.This so that higher speeds than normally possible can be achieved, with the goal beingset to 30 000rpm.In order to be able to design the composite shell correctly a method of calculating theload stresses had to be developed. This was done by the creation of a Matlabprogram, named Spin2Win, capable of calculating the stresses inside a compositemetal hybrid flywheel. Using said Matlab code, combined with modelling andsimulations from SolidWorks, a fully-fledged flywheel was designed complete withdrawings and material specifications.The composite analysis surprisingly shows that the best combination of compositematerials is a mixture of both high strength carbon fibres alongside softer glass fibrescoupled with the weight of the central core. This allowed for control of the radialstresses which was shown to otherwise be the limiting factor when designing rotatingcomposite materials.One of the most interesting, and perhaps even unique, parts of the design is that theelectrical machine has been integrated into the flywheel’s composite shell. Having thetwo entities working together in order to control the radial stresses in thecomposite, by utilizing the weight of the permanent magnets.

Ein großer Vorteil von Kunststoffbauteilen ist neben funktionellen Vorzügen die Kosten- und Gewichtsreduzierung durch integrale Gestaltungsmöglichkeiten. Es können Geometrien umgesetzt werden, die mit metallischen Werkstoffen nur unter hohem Aufwand realisierbar sind. Insbesondere im Bereich der Faser-Kunststoff-Verbunde (FKV) gibt es hohen Forschungsbedarf hinsichtlich Reduzierung von Herstellungskosten, Erhöhung der Langlebigkeit aber auch der Reparaturfähigkeit. Die Erkennung von Defekten ist dabei eine grundlegende Voraussetzung. Für einen FKV-Serieneinsatz im Automobilbau gibt es jedoch kein bekanntes und ausreichendes Prüfkonzept der Schadenserkennung für die geforderten Stückzahlen. Die aus der Luft- und Raumfahrt bekannten Methoden lassen sich aufgrund ihres hohen apparativen Aufwandes und der eingeschränkten Tauglichkeit bezüglich geometrisch komplexer Bauteile nicht unmittelbar übernehmen. Es bestehen andere Anforderungen an ein Prüfkonzept für FKV-Bauteile im Automobilbau. Im Rahmen dieser Arbeit wurden zerstörungsfreie Prüfmethoden hinsichtlich ihrer Eignung zur Detektion nicht sichtbarer Schäden systematisch untersucht und bewertet. Der Fokus lag dabei auf Bauteilen aus kohlenstofffaserverstärkten Kunststoffen des Automobils, die sowohl eine flächige als auch eine mehrfach gekrümmte Bauteilstruktur mit nicht-homogenen Wanddicken aufweisen können. In Abhängigkeit von der Art der Schädigung, etwa Einschlüsse, Zwischenfaserrisse oder Delaminationen wurden die unterschiedlichen Verfahren vergleichend in Hinblick auf Detektionssicherheit, -grenzen und Einschränkungen durch gegebene geometrische sowie werkstoffliche Bauteilausführungen bewertet und ein Konzept für eine fertigungsbegleitende Qualitätssicherung entwickelt.

Carbon nanotubes (CNTs) were successfully grown on the surface of carbon fibre reinforcements in carbon fibre architecture through in-situ catalytic chemical vapour deposition (CCVD). Success was also implemented on powders of oxides and non-oxides, including Y-TZP powder, ball milled alumina powder, alumina grits, silicon carbide powder. Preliminary results have been achieved to demonstrate the feasibility of making ceramic composites consisting of CNTs reinforcements.

Neste trabalho propôs-se a construção de um tubo de material compósito híbrido, com fibra de vidro e fibra de carbono, para utilização como prolongador de prótese de membro inferior a serem fabricadas pela AACD - Associação de Assistência à Criança Deficiente. O objetivo é avaliar as solicitações da prótese para otimizar custo e reduzir a massa. Fez-se inicialmente um levantamento das propriedades dos materiais comerciais utilizados para a fabricação do prolongador para referenciar o desenvolvimento do componente da prótese. Utilizou-se modelagem por elementos finitos para otimizar o componente em função dos esforços biomecânicos a que a prótese é submetida. Nesta modelagem, estudaram-se várias disposições, quantidade e material das camadas de forma a atender às solicitações e minimizar os custos. O levantamento bibliográfico permitiu encontrar uma rota de menor custo para a fabricação de compósito que utiliza um processo de transferência de resina auxiliado a vácuo e pré-formados de vidro e carbono. Como referência, foi fabricado um componente pelo processo de bobinagem filamentar que produz materiais compósitos de qualidade reconhecida. O processo de moldagem por transferência de resina assistido à vácuo, apesar de ter alguns insumos importados, pela sua simplicidade pode ser realizado na própria AACD e se mostrou capaz de obter componentes com custo que viabiliza sua produção sem grandes investimentos em equipamentos. Apesar da redução de algumas das propriedades em relação à peça de referência, o tubo apresentou vantagens na redução de massa e na absorção de impacto. / In this work it was considered a construction of a pipe of hybrid composite material, with carbon and glass fibre, for use as prosthesis extension of inferior member to be manufactured for the Associação de Assistência à Criança Deficiente AACD. The objective is to evaluate the requests of prosthesis to optimize cost and to reduce weight. A survey of the properties of the commercial materials commonly used for the manufacture extension became initially a reference to the development of the final component. A finite element modeling was used to optimize the component in the biomechanics function related to the efforts which the prosthesis is submitted. In this modeling some disposals and numbers of layers, amount and material have been studied to take care of the requests and to minimize the cost. A bibliographical survey allowed finding a shipper route for the manufacture of composite that uses a process of vacuum assisted resin transfer molding and preforms of glass with carbon. As reference, a component was produced using filament winding process to compare the quality of the obtained composite pipe. The process, although to have some imported feed-stock, can be proper carried out by AACD and if it showed capable to produce components with cost that makes possible its production internally. Despite the reduction of some of the properties in relation to the reference part, the component presented advantages such as weight reduction and the impact absorption.

Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving.