Från slutet på 1800-talet till runt 1970-talet gjordes tennisracket i trä och då tekniken inte var så avancerad var de tunga och böjliga. På 1970-talet började dock andra material som exempelvis kolfiber användas som var styvare och gav ett lättare racket. Över tid har metoderna för tillverkningen i trä fallit i glömska vilket gör att undersökningar som denna är intressanta att utföra. Då kolfiber framställs av råolja kan materialet bli mindre attraktivt både ur ett miljö- och ekonomiskt perspektiv då oljepriserna stiger. På grund av detta har företaget Epok Tennis, som arbetet har utförts ihop med, valt att experimentera och prova sig fram i tillverkningen av racket i trä i jakt efter den mest optimala uppsättningen och konstruktionen. Kunskapsläget är dåligt inom området då studie av denna typen generellt görs på större element för användning i exempelvis bostäder och dessa består då framför allt av gran och furu. Därför är det intressant för Epok Tennis att se inverkan av olika träslag som inte vanligtvis används i balkar av i små dimensioner som är jämförbara med tennisracket.Epok Tennis har undersökt hur träracketen byggdes förr och försökt implementera tekniken moderna racket byggs, detta för att skapa en träprodukt som kan fungera lika bra som en modern racket. De viktigaste parametrarna att ta hänsyn till i arbetet var produkternas vikt, styvhet och hållfasthet. I arbetet undersöktes 21 kors- och parallellimmade balkar bestående av totalt sex nordiska träslag. Träslagen i fråga var ask, björk, bok, ek, lönn och valnöt. Sju av balkarna var korslimmade och 14 parallellimade. De korslimmade elementen varierade mellan ett och två tvärgående skikt. Två av balkarna innehöll även produkter som kolfiberduk och linnetyg vilka inte beaktades i beräkningarna men vars resultat var av intresse att analysera. Syftet med arbetet var att undersöka hur olika kombinationer av olika träfanérskivor påverkarböjstyvheten och hållfastheten för en tennisrackets konstruktion. Målet var sedermera att fastställa vilken av balkarna som har högst böjstyvhetoch hållfasthet samt ge förslag om optimal komposituppsättning. Teoretiska beräkningar samt experiment av fyrpunktsböjning utfördes på balkarna där resultaten jämfördes och analyserades. Experimenten utfördes både i balkarnas flat- och kantvisa riktning. Även densiteterna noterades för elementen då konstruktionens totala vikt i slutändan är av stor betydelse.Resultaten av studien visade att de homogena parallellimmade balkarna av björk, lönn och valnöt hade högst böjstyvhet. Vid analys av resultaten noterades att korslimning av elementen generellt försvagade dem i både flat- och kantvis riktning. Till detta ändamål kan det därför vara klokt att endast använda parallellimmade element. I resultatet redovisas även balkarnas knäcklast i kantvisa riktningen.Förekomsten av kvistar i lamellerna ansågs ha en stor inverkan på balkarnas hållfasthet. Därför bör lameller med kvistar försöka undvikas vid framställningen av ramarna till tennisracketen. I förslaget om optimal komposituppsättning har en kombination av lönn och valnöt angetts då dessa visade högst böjstyvhet med avsevärt lägre densitet än björk som dock liknande värde på böjstyvheten.Enligt resultaten av studien är slutsatserna som dragits kortfattat att korslimning generellt försvagar elementen gentemot parallellimning och att bästa komposituppsättning består av lönn och valnöt, i kombination med varandra eller var för sig. / The knowledge of creating wooden tennis rackets has been lost since the emergence of materials like carbon fibre. In this study 21 cross- and parallel laminated beams have been examined, seven of which are cross laminated and 14 parallel laminated. The wood species used were ash, beech, birch, maple, oak and walnut.The purpose of the study was to determine how different combinations of wood lamellas affect strength and stiffness of the beams in terms of bending.The goal was to determine which of the 21 beams had the highest bending stiffness and to give a recommendation of what would be the optimal composite set.Calculations and experiments of four point bending were done in the flat- and edgewise directions, the results of which were compared and analyzed.The results of the study showed that the homogenous parallel laminated beams consisting of birch, maple and walnut had the highest bending stiffness. When analyzing the results, it was found that the parallel laminated beams were generally stronger and stiffer than the cross laminated specimens, for both flat- and edgewise bending.In the recommendation of optimal construction, a combination of maple and walnut has been suggested due to them having similar bending stiffness to birch but significantly lower density.

The mammalian adrenal gland (or suprarenal gland) is a small organ located on the superior aspect of the kidney. The central region of the gland, the medulla, consists of chromaffin cells, which release catecholamines into the blood during periods of stress. This is best known as the 'fight or flight' response and is regulated, in the adult animal, by neuronal signals from the cholinergic sympathetic fibres of the splanchnic nerve. Interestingly, in some mammals, such as rat and human, sympathetic innervation is immature at birth, yet the chromaffin cells can still secrete catecholamines in response to physiological stessors, e.g. hypoxia. Increased plasma catecholamines is thought to provide a vital protective role for the neonatal animal during, and following birth. This is mediated in part by promoting lung fluid absorption, surfactant secretion, heart rate stabilization, and brown fat mobilization. The observation that, in the neonate, catecholamines are secreted in the absence of functional sympathetic innervation suggests that the chromaffin cells possess other mechanisms for directly 'sensing' a fall in blood O2 tension (hypoxia). The primary goal of this thesis was to uncover the mechanisms of oxygen-sensing in developing chromaffin cells from the rat and mouse, using primary short-term cell cultures of chromaffin cells. The experimental approaches relied on patch clamp techniques to record ionic currents and membrane potential, carbon fibre electrochemistry to record catecholamine secretion from cell clusters, and fluorescent indicators to measure reactive oxygen species generation. Hypoxic chemosensitivity was found in embryonic and neonatal, but not juvenile chromaffin cells from both the rat and mouse. Exposure to hypoxia or anoxia caused a reversible suppression of whole-cell current, which was comprised of the differential modulation of three K+ currents: (1) suppression of a large-conductance Ca2+-dependent K+ current; (2) suppression of a delayed rectifier K+ current; and (3) activation of an ATP-sensitive K+ current. Hypoxia also induced membrane depolarization that was not initiated by any of these three voltage-dependent K+ currents. Additionally, hypoxia broadened action potentials in chromaffin cells that showed spontaneous activity, and this was mediated by a prolongation of the time course of membrane repolarization. All of these factors likely contribute to catecholamine secretion by enhancing the influx of Ca2+ through depolarization-activated L-type Ca2+ channels. Two sets of experiments were designed to identify the oxygen sensor in neonatal chromaffin cells. First, cells from transgenic mice, deficient in the gp91^phox component of the putative O2-sensor protein, NADPH oxidase, responded to hypoxia in the same way as wild type cell, indicating that NADPH oxidase is not primarily responsible for oxygen sensitivity in these cells. Second, inhibitors of the proximal electron transport chain (e.g. rotenone and antimycin A) mimicked and attenuated the hypoxic response, while inhibitors of the distal electron transport chain (cyanide) and uncouplers of oxidative phosphorylation (2,4-dinitrophenol) had no effect. Furthermore, reactive oxygen species production, primarily H2O2, decreased during exposure to hypoxia or inhibitors of the proximal electron transport chain, revealing a potential mitochondrial mechanism for 'sensing' of the hypoxic stimulus. Reduced oxygen availability to the electron transport chain is proposed to cause a fall in cellular reactive oxygen species (ROS), principally H2O2. This fall in ROS signals closure of Ca2+-dependent and Ca2+-independent K+ channels, which causes broadening action potentials and increases Ca2+ influx. The latter is further enhanced by the hypoxia-induced membrane depolarization, which in turn increases the probability of cell firing. The rise in intracellular Ca2+ then acts as the signal for catecholamine release from the chromaffin cells. / Thesis / Doctor of Philosophy (PhD)

Increasing demand for structural health monitoring in space highlights the need to make the creation of these systems more accessible. This study investigates the potential of additive manufacturing to achieve this goal by characterizing a self-sensing material made of a commercially available 3D-printed continuous carbon fibre filament. The results demonstrate the feasibility of converting the filament into a strain sensor with improved sensitivity compared to conventional foil strain gauges. Mechanical and electromechanical properties of the self-sensing material were characterized, including an ultimate tensile strength of 45.09 ± 3.45 MPa, a failure strain of 38.93 ± 3.41%, and a base resistance of 759.11Ω. The tensile gauge factor was calculated to be 467.06 ± 375.90 within the strain range of 0% to 3.8% with a linearity (R2) of 0.93. For the first time, a systematic literature review compares mechanical and electromechanical properties to enable material selection for mechanical design incorporating self-sensing material. The study highlights that the spread of material properties in a group of materials indicates how well-developed a material is for self-sensing purposes. This study advances our understanding of the feasibility of using additive manufacturing to create self-sensing materials for structural health monitoring systems and opens up new avenues for further research.

Assessing existing bridges is an important task in the sustainable management ofinfrastructure. In practice, structural bridge assessments are usually conducted usingtraditional and standardised methods, despite knowledge that these methods oftenprovide conservative estimates. In addition, more advanced methods are available, suchas nonlinear finite element (FE) analysis, that are used for research purposes and cansimulate the structural behaviour of bridges more accurately. Therefore, it would beuseful to develop practical and reliable procedures for refined assessments using theseadvanced techniques.Focusing on the ultimate load-carrying capacity of existing concrete bridges, this thesispresents a procedure for structural assessments. The fundamental idea is to improve theassessment successively, as necessary to predict bridges’ structural behaviour adequately.The procedure involves a multi-level assessment strategy with four levels of structuralanalysis, and an integrated framework for safety verification. At the initial level (Level 1)of the multi-level strategy, traditional standardised methods are used, no failures arecovered implicitly in the structural analysis and action effects are verified using localresistances calculated using analytical models. In the subsequent enhanced levels (Levels2 – 4), nonlinear FE analysis is used for stepwise integration of the verification of flexural,shear-related and anchorage failures into the structural analysis. The framework for safetyverifications includes partial safety factor (PSF), global resistance safety factor (GRSF) andfull probabilistic methods. Within each of these groups, verifications of desired safetymargins can be conducted with varying degrees of complexity.To demonstrate and evaluate the proposed structural assessment procedure, comparativestudies have been carried out, based on full-scale tests of a prestressed concrete bridge.This was the Kiruna Bridge, located in the northernmost city in Sweden, which was duefor demolition as part of a city transformation project, necessitated by large grounddeformations caused by the large nearby mine. Thus, it was available for destructiveexperimental investigation within the doctoral project presented in this thesis. The bridgehad five continuous spans, was 121.5 m long and consisted of three parallel girders with a connecting slab at the top. Both the girders and slab were tested to failure to investigatetheir structural behaviour and load-carrying capacity. Non-destructive and destructivetests were also applied to determine the residual prestress forces in the bridge girders andinvestigate the in situ applicability of methods developed for this purpose. The so-calledsaw-cut method and decompression-load method were used after refinement to enabletheir application to structures of such complexity. The variation of the experimentallydetermined residual prestress forces was remarkably high, depending on the sectioninvestigated. There were also high degrees of uncertainty in estimated values, and thusare only regarded as indications of the residual prestress force.Level 1 analysis of the multi-level assessment strategy consistently underestimatedcapacity, relative to the test results, and did not provide accurate predictions of the shearrelatedfailure observed in the test. With linear FE analysis and local resistance modelsdefined by the European standard, Eurocode 2, the load-carrying capacity wasunderestimated by 32 % for the bridge girder and 55 % for the bridge deck slab. At theenhanced level of structural analysis (Level 3), nonlinear FE analyses predicted thecapacities with less than 2 % deviation from the test results and correctly predicted thefailure mode. However, for existing bridges there are many uncertainties, for instance,the FE simulations were sensitive to the level of residual prestressing, boundaryconditions and assumed material parameters. To accurately take these aspects intoaccount, bridge-specific information is crucial.The complete structural assessment procedure, combining the multi-level strategy andsafety verification framework, was evaluated in a case study. Experiences from theprevious comparative studies were used in an assessment of the Kiruna Bridge followingthe Swedish assessment code. The initial assessment at Level 1 of the multi-level strategyand safety verification, using the PSF method, indicated that the shear capacity of one ofthe girders was critical. The most adverse load case (a combination of permanent loads,prestressing and variable traffic loads) was further investigated through enhancedstructural analyses implicitly accounting for flexural and shear-related failures (Level 3).Nonlinear FE analysis and safety evaluation using the PSF method, several variants of theGRSF method and the full probabilistic analysis for resistance indicated that the permittedaxle load for the critical classification vehicle could be 5.6 – 6.5 times higher than thelimit obtained from the initial assessment at Level 1. However, the study also indicatedthat the model uncertainty was not fully considered in these values. The modeluncertainty was shown to have strong effects on the safety verification and (thus)permissible axle loads. The case study also highlighted the need for a strategy forsuccessively improving structural analysis to improve understanding of bridges’ structuralbehaviour. The refined analysis indicated a complex failure mode, with yielding of thestirrups in the bridge girders and transverse flexural reinforcement in the bridge deck slab,but with a final shear failure of the slab. It would be impossible to capture suchcomplexity in a traditional standardised assessment, which (as mentioned) indicated thatthe shear capacity of the girder limited permissible axle loads. However, nonlinear FEanalyses are computationally demanding, and numerous modelling choices are required.Besides a strategy for rationally improving the analysis and helping analysts to focus oncritical aspects, detailed guidelines for nonlinear FE analysis should be applied to reduce the analyst-dependent variability of results and (thus) the model uncertainty. Clearly, toensure the validity of bridge assessment methods under in situ conditions, theirevaluations should include in situ tests. This thesis presents outcomes of such tests, therebyhighlighting important aspects for future improvements in the assessment of existingbridges.

At launching the shell body, especially the backplane of the shell body, will be exposed to very high stresses due to acceleration, pressure and increased temperature from the propellant combustion. Defects in the shell body could in worst case for example result in high temperature gas leakage into the warhead and thereby ignite the explosives before exiting the launcher. This kind of explosion results in serious damages and can seriously injure both the gunner and other people in the surroundings. According to earlier study, carbon fibre reinforced epoxy with filament winding manufacturing method was the primary focus. The purpose of this master thesis was to investigate requirements and testing methods on a shell body manufactured in composite that will guarantee the safety of the gunner and surroundings in the launch phase. The pre-study conducted in this project showed that matrix cracks and fibre breakages are most common defects in the shell body that occur during launching affected by burst pressure. Matrix crack is the less dangerous defect among the impact damage types. Discussion with composite manufacturing companies showed that fibre breakage is a very serious type of defect since more breakage of fibres leads to the shell body have reduced stresses and cannot built-up the fully potential burst pressure during launching.   Two requirement specifications were carried out, one for the shell body and another for the detection methods. These were created by own research and ideas according to found information, telephone- and e-mail contact with experts in areas and with personnel at Saab Dynamics AB. Some requirements for the shell body were that it should be fully usable after drop tests from different heights, vibration and transportation tests yield no cyclic damage after a long transport. Furthermore, the shell body should always use a fully isolated driving band to not have hot explosive gases penetrated into critical sections which results in detonation already in the launcher barrel. The most important requirements for the detection methods were to have depth analysis, high reliability and in-field inspection.   Elimination- and decision matrices were made to find which detection methods should be the final selections in order to find the defects in a shell body. The detection methods which did not fulfil the criteria from each separate matrix were eliminated and did not proceed further as a concept. Eliminations were performed in concept generation phase (elimination matrix) and concept selection phase (decision matrix). In final selection phase a couple of methods were chosen that together found as many defects as possible.   By using both acoustic emission and shearography all the critical defects and a wide range of other defects can be detected with very high reliability and resolution at an acceptable cost. These two methods “interact” perfectly with each other. Acoustic emission is the best method to find fibre breakage and matrix cracks, which are the most commonly occurring defects during launching. But shearography does not have a good detectability of fibre breakage and matrix cracks. On the other hand, shearography has good detectability of both planar- and volumetric defects. It is concluded that only two inspection methods, i.e. acoustic emission and shearography are needed to detect all of the possible defects in the grenade shell body. This is more economical solution requiring smaller space and fewer operators compared to one separate NDT method for detecting each type of defect. / Vid utskjutning av granathylsan utsätts framförallt bakplanet, för mycket höga påfrestningar genom acceleration, tryck och förhöjd temperatur från krutförbränningen. Vid en genombränning av granatskalet skulle sprängämnet i verkansdelen kunna tändas redan i eldröret och orsaka en vapensprängning. Den här typen av explosion resulterar i allvarliga skador både för skytten samt folk i dess omgivning.   Med hänsyn till tidigare studier har det varit fokus på kolfiberförstärkt epoxi som är tillverkad av fiberlindning. Syftet var att utreda kravställningar och metoder för provning, som garanterar skyttens och omgivningens säkerhet i utskjutningsfasen av en granat tillverkad av kompositmaterial.   Från förstudien i denna rapport visade sig att matrissprickor och fiberbrott är de vanligaste defekter som uppstår i granathylsan under utskjutningsfasen där den största påverkan är ifrån explosionstrycket. Matrissprickor är de mindre farliga defekter av de som uppstår under intryckning. Diskussion med komposittillverkande företag visade att fiberbrott är en väldigt farlig typ av defekt eftersom fibrerna står för styrkan och brott av fibrer leder till att granathylsan klarar av att utsättas för lägre påfrestningar och kan inte hjälpa till att bygga upp det önskvärda trycket som önskas under utskjutningen.   Två kravspecifikationer utfärdades, en för granathylsan och en annan för detekteringsmetoderna. Dessa två skapades genom egen studie och idéer med hänsyn till hittad information, ifrån telefon- samt email kontakt med experter inom områdena samt med hjälp av personal på Saab Dynamics AB. Några krav som valdes för granathylsan var att den ska vara fullt användbar efter fallskärmsprovning från olika höjder, vibration- och transport tester för att inte få cykliska skador efter en lång transportering samt att alltid ha en fullt isolerad gördel så att inte de heta gaserna från explosivorna tänds redan i eldröret vilket orsakar vapensprängning. Några krav för detekteringsmetoder var att de ska kunna göra mätningar/analyser på djupet, ha hög trovärdighet samt vara portabel.   Eliminering- och beslutsmatriser gjordes för att hitta vilka detekteringsmetoder som skulle bli de slutliga valen i jakten på att finna defekterna i granathylsan. De metoder som inte uppfyllde kriterierna från respektive matris blev eliminerade. Elimineringen utfördes i faserna för konceptgenerering och konceptval. I slutliga valet valdes ett par lämpliga metoder som tillsammans hittar så många defekter som möjligt.   Genom att använda akustisk emission samt shearografi hittades samtliga kritiska defekter plus många andra som inte anses vara kritiska med väldigt hög trovärdighet och upplösning till ett mer acceptabelt pris. Metoderna samverkar väldigt bra med varandra eftersom akustisk emission är bästa metoden att hitta fiberbrott och matrissprickor vilket är vanligt förekommande i utskjutningsfasen. Shearografi har inte samma detekterbarhet på dem två defekterna men de har å andra sidan istället väldigt god detekterbarhet på både volymetriska- och plana defekter.   Slutsatsen är att endast två metoder behövdes för att finna alla defekter vilket blir mer ekonomiskt, tar mindre plats och behöver färre certifierade operatörer jämfört med om man ska ha en detekteringsmetod för att finna respektive defekt.

Mit zunehmendem Alter zeigt das Verbundverhalten von Multifilamentgarnen aus alkaliresistentem Glas (AR-Glas) oder Kohlenstoff in Abhängigkeit von der Zusammensetzung der zementgebundenen Matrix eine sehr unterschiedliche Entwicklung. Während bei AR-Glas teilweise drastische Verluste des Leistungsvermögens zu verzeichnen sind, treten diese bei Kohlefasern nicht auf. Zur Untersuchung der Phänomene wurden beidseitige Garnauszugversuche durchgeführt und die Interphase zwischen Filamenten und Matrix im Rasterelektronenmikroskop (ESEM) untersucht. Die unterschiedlichen mechanischen Eigenschaften stehen in Zusammenhang mit verschieden ausgeprägten Mikrostrukturen der Interphasen. Welche Ursachen die unterschiedliche morphologische Entwicklung der Interphasen hat, ist Gegenstand aktueller Arbeiten.

Nowadays, thin-walled load bearing structures can be realised using textile reinforced concrete (BRAMESHUBER and RILEM TC 201-TRC [1]). The required tensile strength is achieved by embedding several layers of textile. By means of the laminating technique the number of textile layers that can be included into the concrete could be increased. To further increase the first crack stress and the ductility as well as to optimize the crack development, fine grained concrete mixes with short fibres can be used. By a schematic stress-strain curve the demands on short fibres are defined. Within the scope of this study, short fibres made of glass, carbon, aramid and polyvinyl alcohol are investigated in terms of their ability to fit these requirements. On the basis of these results, the development of hybrid fibre mixes to achieve the best mechanical properties is described. Additionally, a conventional FRC with one fibre type is introduced. Finally, the fresh and hardened concrete properties as well as the influence of short fibres on the load bearing behaviour of textile reinforced concrete are discussed.

Fibre composite materials are gaining recognition in civil engineering applications as a viable alternative to traditional materials. Their migration from customary automotive, marine, aerospace and military industries into civil engineering has continued to gain momentum over the last three decades as new civil engineering applications develop. The use of fibre composite materials in civil engineering has now evolved from non-structural applications, such as handrails and cladding, into primary structural applications such as building frames, bridge decks and concrete reinforcement. However, there are issues which are slowing the use of fibre composite materials into civil engineering. Issues include high costs, difficulties in realising potential benefits, general lack of civil engineers' familiarity with the material and relatively little standardisation in the composites industry. For composites to truly offer a viable alternative to traditional construction materials in the civil engineering marketplace, it is essential that these issues be addressed. It is proposed that this situation could be improved by demonstrating that potential benefits offered by composites can be achieved with familiar civil engineering forms. These forms must be well suited to fibre composite materials and be able to produce safe and predictable civil engineering structures with existing structural engineering methods. Of the numerous structural forms currently being investigated for civil engineering applications, the truss form appears particularly well suited to fibre composites. The truss is a familiar structural engineering form which possesses certain characteristics that make it well suited to fibre composite materials. In this research a novel monocoque fibre composite truss concept was developed into a working structure and investigated using analytical and experimental methods. To the best of the author's knowledge the research presented in this thesis represents the first doctoral research into a structure of this type. This thesis therefore presents the details of the development of the monocoque fibre composite (MFC) truss concept into a working structure. The developed MFC truss was used as the basis for a detailed investigation of the structural behaviour of the MFC truss elements and the truss as a whole. The static structural behaviour of the principal MFC truss elements (tension members, compression members and joints) was investigated experimentally and analytically. Physical testing required the design and fabrication of a number of novel test rigs. Well established engineering principles were used along with complex finite element models to predict the behaviour of the tested truss elements and trusses. Results of the theoretical analysis were compared with experimental results to determine how accurately their static structural behaviour could be predicted. It was found that the static structural behaviour of all three principal truss elements could be accurately predicted with existing engineering methods and finite element analysis. The knowledge gained from the investigation of the principal truss elements was then used in an investigation of the structural behaviour of the MFC truss. Three full-scale MFC trusses were fabricated in the form of conventional Pratt, Howe and Warren trusses and tested to destruction. The investigation included detailed finite element modelling of the full-scale trusses and the results were compared to the full-scale test results. Results of the investigation demonstrated that the familiar Pratt, Howe and Warren truss forms could be successfully manufactured with locally available fibre composite materials and existing manufacturing technology. The static structural behaviour of these fibre composite truss forms was accurately predicted with well established engineering principles and finite element analysis. A successful marriage between fibre composite materials and a civil engineering structure has been achieved. Monocoque fibre composite trusses have been developed in the familiar Pratt, Howe and Warren truss forms. These structures possess characteristics that make them well suited to applications as primary load bearing structures.

This thesis explores new methods for achieving load-carrying joints between the dissimilar materials of continuous fibre reinforced polymer matrix composites and structural metals. The new composite-to-metal joining methods investigated in this work exploit the metal-to-metal joining techniques of arc micro-welding, resistance spot welding, and metal filler brazing, to form novel micro-architectured metal adherends that can be used for enhanced composite-to-metal joining. Through a combination of equipment instrumentation and metallographic inspection of fabricated prototype joints, understanding is gained of how materials respond when processed by manufacturing techniques that have not previously been exploited for dissimilar material joining. Mechanical testing of prototype joints; both to ultimate loading strength and partial failure states, with subsequent inspection of specimens and comparative performances evaluation enabled joining performance characterisation of the new joining methods. Key results include: the identification of micropin reinforced adhesive joints to exhibit pseudo-ductile failure characteristics, resistance spot weld reinforcement of adhesive joints to boost bonding performance, and the use of a polymer infused metal foam to overcome difficulties of thermoplastic to metal adhesion. Through this work knowledge of how novel micro-architectures reacted under mechanical loading enabled insights to be gained into how perceived manufacturing defects can benefit joining performance. Such examples include, localised material weakness that lead to global pseudo-ductile failure behaviour, and low-strength secondary joining mechanisms boosting primary load transfer systems. By comparison of the diverse joining methods investigated in this work, trends were identified that suggest joining performance between the two dissimilar materials is improved by increasing the direct interaction between the composite reinforcement fibres and the metal structure. It is demonstrated that joining improvements are gained by forming mechanical connections between metals and composite precursory material before the final manufacturing process of the composite.

With industries aiming at higher efficiencies, lightweight parts, and easier manufacturability there has been a recent trend of replacing the metallic materials with polymeric materials and its composites. Particularly in the automotive industry, there is a demand of replacing metallic material of bushes and bearings with polymer based materials (PBM). For these heavy performance requirements (as in automobiles), the commonly used industrial polymers like Acetal and Nylon fail to provide good mechanical and tribological performance. High-performance polymer like Polyphenylene Sulfide (PPS) is a relatively newer material and shows a potential of being a PBM alternative for metallic bearings in automobiles if their tribological performance can be improved.  One of the ways of improving the tribological performance of the polymer is by the addition of filler material, hence making a polymer composite. In this study, we used Short Carbon Fibre as micro-reinforcement material and Nano-diamonds and Graphene Oxide as nano-reinforcement material to make PPS composites. The varying mechanical and tribological behaviour of PPS composites with different weight percentage of reinforcement materials was investigated. The optimum composition of the reinforcement materials was identified, which resulted in significant improvement in mechanical and tribological properties of the base material.