Since their discovery Carbon Nanotubes (CNTs) have attracted much interest from many fields of the scientific community owing to their range of unique and impressive properties. Measurements of the mechanical properties of these nanoscale molecules have shown strengths up to five times greater than that of steel at only a quarter of the density. Consequently many have attempted to unlock these remarkable properties by creating nano-composite structures where CNTs effectively reinforce materials with little increase in density. Unfortunately the tendency of CNTs to form agglomerations when allowed to disperse in fluid suspensions has made this process non trivial, and led to difficulties in achieving effective reinforcement when simply mixing CNTs into a matrix material. As a result it has become clear that new approaches to composite construction will be required if effective composite reinforcement using CNTs is to be achieved. Recent advances in CNT synthesis using Chemical Vapour Deposition (CVD) where tall forests of these nanoparticles are grown from the vapour phase have begun to solve the agglomeration problem. These forests are produced in aligned and dispersed arrays, and wetting of these structures with polymer matrices has demonstrated improvements in modulus of several hundred percent. These improvements arise as the CNTs retain both the dispersion and alignment of the forest when incorporated into the matrix thus overcoming the difficulties observed using traditional manufacture methods. New complications arise when attempting to extend these promising results to larger scale composite components owing to the typically millimetre size of CVD grown vertically aligned CNT (VACNT) forests. From these results it follows that to create large composite parts it will be required to incorporate many individually CVD grown VACNT forests into a single composite structure. Strategies to achieve such a composite are being developed, with a range of ideas extending from knowledge gained from the emerging technology of additive manufacture (AM) described as ‘...the process of joining materials to make objects from 3D model data, usually layer upon layer....’. Indeed it is desirable to reinforce materials used in AM processes and the nano scale diameter of CNTs makes them the perfect choice owing to their high aspect ratios at the micron scale. In this thesis investigations are conducted into the feasibility of manufacturing CNT composite structures using CVD grown forests and AM techniques. These investigations include measurement of the anisotropic mechanical properties of composite samples, and studies of the wetting interactions that occur between CNT forests and polymer materials. Composite samples are constructed and tested mechanically in the transverse orientation and results compared to traditional fibre composite reinforcement models in order to understand the material properties that can be expected if such an AM process is achieved. Results show greater mechanical improvements in transverse modulus than expected, and these results are attributed to the wavy nature of individual CNTs within forest structures providing multi directional reinforcement to the matrix material. Further studies are conducted to investigate the flow of molten thermoplastic materials into CNT forest structures under capillary driven flow. Thermoplastics were allowed to flow into VACNT forests before being cooled and inspected using micro x-ray computed topography (μ-CT) to gain an understanding of the wetting mechanism. Results from μ-CT scans show that the polymer flows into the structure in peaks of similar radius. Finally dynamic investigations were conducted into the fast capillary driven flow of a low viscosity thermoset resin into VACNT forests using a high speed camera. Results are fitted to traditional models for dynamic capillary driven flow in porous media and an effective radius and porosity is calculated for VACNT forests. Experimental values illustrate that these nanoscale structures still fit to traditional flow models of fluids where the height of capillary rise is proportional to the square of the elapsed time. These results provide a further step in understanding methods of incorporating many VACNT structures into polymeric matrices to achieve large scale effective polymer VACNT composite materials.

The titanium alloy Ti-6Al-4V has been favoured by the aerospace industry for the past several decades due to its good combination of specific mechanical properties, alongside corrosion and fatigue resistance. Titanium alloys are naturally suited to the near net shape processing technique of Additive Manufacture (AM) due to both the inherent high cost of the raw materials, and the difficulties associated with machining the alloys. Unfortunately, the combination of Ti-6Al-4V with AM has been found to lead to undesirable microstructures with respect to large columnar prior β grains being found to grow potentially across the entire height of builds. This microstructure has been shown to lead to property anisotropy and poor fatigue resistance. However, it has recently been found that the integration of an additional process step that lightly deforms the deposited material between added layers leads to the refinement of this undesirable microstructure. This work characterises the effect that two different deformation processing techniques have on two different additive manufacturing processes; the effect of peening on a laser-powder AM technique, and the effect of rolling on an electric arc-wire AM technique. In both cases far more randomly textured prior β grains were found with an average grain size of > 100 µm rather than mm long columnar grains with a common growth direction formed in the non-deformed builds. The refined β microstructure was found to lead to a reduction in texture of the room temperature alpha phase. The low stains involved (>10%) indicated that the refined grain structures did not form by traditional recrystallisation mechanisms. In-situ EBSD measurements at temperatures spanning the alpha → β phase transformation have been used to observe the growth of new β orientations from crystallographic twins in the deformed microstructure that may explain the origin of the refined grains. New β orientations were observed to grow from twinned alpha colonies and from between alpha laths, where the new β is found to grow sharing a twinning relationship with the residual β. Simulation of both of the individual processing steps under laboratory conditions has been found to successfully replicate the refinement observed in process. Orientation analysis suggests that twinning of the residual β could lead to the texture observed in the refined grains. It is therefore suggested that the refined grains are formed from β twinned regions in the deformed material growing under the alpha → β phase transformation, as the material is heated by the next added layer during AM.

Additive Manufacture (AM) is a novel manufacturing method; it is a process of forming components by adding materials. Owing to material saving and manufacturing cost saving, more and more research has been focused on metal AM technologies. WAAM is one AM technology, using arc as the heat sources and wire as the material to create parts with weld beads on a layer-by-layer basis. The process can produce components in a wide range of materials, including aluminum, titanium and steel. High deposition rate, material saving and elimination of tooling cost are critical characteristics of the process. Cost estimation is important for all companies. The estimated results can be used as a datum to create a quote for customers or evaluate a quote from suppliers, an important consideration for the application of WAAM is its cost effectiveness compared with traditional manufacture methods. The aim of this research is to find a way to develop a cost estimating method capable of providing manufacturing cost comparison of WAAM with CNC. A cost estimation model for CNC machining has been developed. A process planning approach for WAAM was also defined as part of this research. An Excel calculation spreadsheet was also built and it can be easily used to estimate and compare manufacture cost of WAAM with CNC. Using the method developed in this research, the cost driver analysis of WAAM has been made. The result shows that reduced material cost is the biggest cost driver in WAAM. The cost comparison of WAAM and CNC also has been made and the results show that with the increase of buy-to-fly ratio WAAM is more economical than CNC machining.

This thesis investigates the application of online monitoring for the optimisation of flow chemistry, as well as how additive manufacturing can aid the integration of analysis and confer new functionality to flow reactors. The additive manufacturing (AM) processes used were stereolithography (SL) and the metal printing techniques selective laser melting (SLM) and ultrasonic consolidation (UC). Chapter 1 contains a short literature review, intended to give a clear background to the work contained herein. The literature reported gives a brief introduction to flow chemistry and some of the instrumentation used to perform it. Additionally, the evolution of reactor design is investigated leading to an overview of the use of AM for custom reactors. The subsequent use of online analytical technologies and how they relate to the enhancement of flow chemistry is discussed, as well as some of the protocols that have been employed to date to facilitate automated reaction optimisation. Chapter 2 investigates the design and manufacture of flow cells capable of online spectroscopy, as well as the integration of spectroscopic monitoring capability directly into reactors. In addition, the use of AM to produce accessories, not necessarily part of the wetted flow path, was investigated and showed that many useful parts such as fibre optic holders and screws could be produced. The capability of these flow cells was assessed through standard material analysis as well as through the online analysis of flow chemistry. In particular, the use of SL has enabled the production of flow cells with features smaller than 100 microns. This allowed in situ spectroscopy to be performed by embedding fibre optics directly adjacent to the flow channel, offering a new way for reaction monitoring by ultraviolet (UV) spectroscopy to be performed cheaply, and with full user control over the flow cell specification. No additional quartz features were required for these cheap and highly customisable parts. Flow cells of larger path lengths were also produced, and their performance tested, identifying designs and materials suitable for the inline analysis of flow chemistry. These designs were then successfully incorporated directly within the flow channels of larger scale reactors, tailored specifically to commercial flow equipment, for true inline analysis of flow chemistry. Chapter 3 examines the use of metal reactors formed through more expensive printing processes, SLM and UC. As the parts these techniques produce are fully dense, chemically resistant and thermally stable, they were used to perform high temperature chemistry, taking solvents substantially above their boiling points to accelerate reactions and perform them in a fraction of the time of the batch process. UC was also used to produce a reactor with a copper flow path and the possibility of reaction catalysis performed with active metal sections was investigated, revealing that chemical modification of the reactor surface greatly improved the reaction yield. UC was also utilised to produce a flow reactor incorporating a thermocouple in the main body, close to the flow channel to enable accurate reaction temperatures to be measured, a significant improvement over the temperature control offered through the flow instrument. This represents the first use of UC for the production of complicated geometry flow reactors and this work has shown that many more applications of the technique for flow chemistry should be investigated. The ability to perform light mediated coupling reactions in AM produced reactors was also demonstrated successfully for the first time, and further to this that the extended UV curing of SL reactors is crucial for improved robustness of these parts. Chapter 4 centres on the use of online analytical methods to provide rapid, selective, and quantitative online analysis of flow chemistry. This chapter also outlines some of the steps required for automation to be possible, including equipment specifications and the coding approach undertaken to integrate multiple different instruments. A combination of online nuclear magnetic resonance (NMR) spectroscopy analysis and automated experiment selection was then used to optimise a pharmaceutically relevant, photoredox catalysed, C-N coupling reaction between amines and aryl halides, performed under continuous flow conditions for the first time. This optimisation required minimal user input, operating completely unattended, and revealed that lower concentrations of catalyst could be employed than previously identified, reducing the amount of toxic and expensive metal salts required, while achieving high conversion of the starting material. In summary, this thesis has demonstrated that AM, in particular SL, can be used for the production of new high resolution microfluidic flow cells, as well as larger scale flow cell designs which can be integrated into the body of large reactors, not easily performed with other manufacturing methods. SL has also been used to produce reactors capable of performing light catalysed reactions directly, with no further modifications. The use of metal printing AM techniques has allowed in situ catalysis and high temperature, high pressure reactions to be carried out with ease. Finally, the use of online NMR with computer control and experiment automation has allowed the rapid optimisation of a pharmaceutically important C-N coupling reaction.

<p>  </p> <p>The additive manufacturing of energetic materials is a novel way to alter the properties of an energetic material without necessarily changing its chemical structure. There are many methods of additive manufacturing which can be applied to energetic material fabrication, each of which have unique advantages and disadvantages. The most well characterized additive manufacturing method is the commercially refined technique of fused filament fabrication (FFF) printing. FFF manufacturing techniques can be applied to additively manufacture thermoplastic energetic materials. The thermoplastic aluminum and polyvinylidene difluoride (Al/PVDF) system is suitable for manufacture with FFF techniques, shapeable into pyrotechnics with custom geometries using commonly available FFF printers. This theoretically allows Al/PVDF systems to be tailored for a wide variety of multifunctional needs, such as reactive structures. Following a literature review describing energetic material additive manufacturing techniques, this thesis focuses on the creation of outwardly identical Al/PVDF samples and the use of a geometric correction factor to control for uneven feedstock diameter. By varying the infill pattern, infill density, and interior geometry, different sample energy densities were obtained and observed during combustion. High speed videography measurements and the mass of individual samples were used to estimate the overall energy release rate. An Ashby plot contrasting the energy density and energy release rate was obtained. While full density printed samples burned similar to cast propellant strands in a linear burn, the energy release rates of additively manufactured Al/PVDF could be increased via convective combustion by varying the infill type and density. These results have significance for the fields of structural energetic materials and for additive manufacturing studies of energetic materials.</p>

This thesis aims to investigate the use of additive manufacturing (AM) as a novel manufacturing process for the production of milli-scale chemical reaction systems. Five well developed additive manufacturing techniques; stereolithography (SL), selective laser melting (SLM), fused deposition modelling (FDM), ultrasonic additive manufacture (UAM) and selective laser sintering (SLS) were used to manufacture a number of miniaturised flow devices which were tested using a range of organic and inorganic reactions. SL was used to manufacture a range of functioning milli-scale flow devices from Accura 60 photoresin, with both simple and complex internal channel networks. These devices were used to perform a range of organic and inorganic reactions, including aldehyde and ketone functional group interconversions. Conversion of products within these reactors, were shown to be comparable to commercially available milli-scale coil reactors. More complex designs, which allowed SL parts to be integrated to existing flow and analytical instrumentation, allowed us to develop an automated reaction analysis and optimisation platform. This platform allowed precise control over the reaction conditions, including flow rate, temperature and reagent composition. We also designed a simplex type reaction optimisation software package that could input data in the form of reaction conversions, peak intensities, and thermocouple data, and generate a new set of optimal reaction conditions. SL parts which incorporated embedded analytical components were also manufactured, which allowed us to perform inline reaction analysis as a feedback method for input into the optimisation platform. Stereolithography was shown to be a highly versatile manufacturing method for designing and producing these flow devices, however the process was shown to be still limited by the range of processable materials currently commercially available. SLM was also used to manufacture a number of functioning milli-scale flow devices from stainless steel and titanium, which had simplistic internal channel designs of diameters ranging from 1 to 3 mm. Again, SLM parts were manufactured which incorporated embedded analytical components, which could be integrated into an automated reaction platform. These devices, unlike parts produced via SL, could be attached to heating platforms to allow us to perform high temperature reactions. This control over the reaction temperature formed an essential part of the reaction optimisation platform. These parts were again used to perform a ketone functional group interconversion. Internal structures of these SLM parts were also visualised via micro computed tomography (μCT or microCT) scanning as well as optical microscopy. FDM was used throughout the project as an inexpensive method of prototyping parts which were to be manufactured via more expensive manufacturing processes. This prototyping allowed the optimisation of intricate design features, such as the manufacture of an inline spectroscopic flow cell for integration with a commercially available LC system. FDM was also proposed as a customisable approach to designing and manufacturing flow devices with embedded components, however the current limitations in build resolution and materials choices severely limited the use of FDM for this application. UAM was also proposed as a novel manufacturing process whereby the build process would allow discrete components to be embedded directly into a flow channel. This was demonstrated by embedding a type-k thermocouple across a 2 mm channel. The data from this thermocouple was monitored during a heated reaction, and used as a method of determining the exact reaction conditions the reaction medium was being exposed to. SLS was also proposed as a possible manufacturing method for milli-scale flow devices, however it proved difficult to remove un-sintered powder from parts with internal channel diameters as high as 5 mm. It was shown that this powder was forming a dense semi solid, due to the large degree of shrinkage upon cooling of the SLS parts, which was compressing the powder. More research into optimum processing conditions is required before SLS could be used for the production of intricate channel networks.

Atualmente a área de saúde vem buscando auxílio na engenharia para a contribuição no estudo e confecção de próteses para casos específicos de fraturas ou doenças ósseas. Com o avanço da tecnologia surgiram processos de manufatura que tornam possível a fabricação de próteses personalizadas. Uma dessas tecnologias é a manufatura aditiva. O grande desafio no momento está na fabricação de próteses por manufatura aditiva que combinem desempenho biomecânico e resistência estrutural. Nesse contexto, o objetivo deste trabalho é desenvolver elementos de fixação, especificamente âncoras de sutura de polímeros PEEK e PEKK, considerando seus requisitos estruturais através de simulações pelo método dos elementos finitos, e considerando que sejam fabricadas através de processos de manufatura aditiva. Este desenvolvimento permitirá a substituição de âncoras de sutura de liga de titânio, hoje largamente empregadas pelos cirurgiões, por âncoras de sutura de polímeros biocompatíveis, o que possibilitará que estes polímeros sejam absorvidos pelo corpo humano em curto e médio prazo, permitindo a completa restituição do osso afetado, melhorando a qualidade de vida do paciente pós-cirurgia. Os resultados obtidos neste trabalho indicam que a técnica poderá resultar em próteses com a biocompatibilidade desejada e resistência mecânica adequada. Próteses permanentes (articulações) ou provisórias (âncoras de sutura) seriam um dos critérios para a escolha do material a ser utilizado, absorvível ou não pelo corpo humano. / Nowadays medicine is searching assistance from engineering that may contribute in studies and confection of prothesis to specific cases of fractures and bone diseases. With the advance of technology new processes of manufacture were risen, making possible the confection of personalized prothesis. The biggest challenge of the moment is in the manufacture of additive prothesis that can combine biomechanics performance and structural resistance. In this context, the objective of this dissertation is to develop PEEK and PEKK polymer suture anchors, considering its structural requirements, taking into account their mechanical strength, through simulation by the finite element method, and considering additive manufacturing processes. This development will allow the replacement of titanium alloy suture anchors, now widely used by surgeons by suture anchors of biocompatible polymers, which enable these polymers to be absorbed by the human body in the short and medium term, allowing full regeneration of affected bone, improving the quality of life of the patient. The results of this study indicate that the technique could result in prosthesis with the desired biocompatibility and adequate mechanical strength. Permanent prosthesis (joints) or temporary (suture anchors) would be one of the criteria for the choice of material to be used, absorbable or non absorbable by the human body.

Selective electron beam melting (SEBM) is a promising powder bed Additive Manufacturing technique for near-net-shape manufacture of high-value titanium components. An extensive research program has been carried out to characterise in 3D the size, volume fraction, and spatial distribution of the pores in model samples, using X-ray computed tomography (XCT), and correlate them to the SEBM process variables. The average volume fraction of the pores (97.5 %) where fatigue cracks would initiate based on the relative stress intensity factor of all the pores. In contrast, crack growth was found to be insensitive to porosity, which was attributed to the much higher stress concentration generated by the crack in comparison to the pores. Some crack diversion was associated with the local microstructure, with prior β grain boundaries often coincident with crack diversion.

For many years, the biggest issue that causes discomfort and hygiene issues for patients with lower limb amputations have been the interface between body and prosthetic, the socket. Often made of an inflexible, solid polymer that does not allow the residual limb to breathe or perspire and with no consideration for the changes in size and shape of the human body caused by changes in temperature or environment, inflammation, irritation and discomfort often cause reduced usage or outright rejection of the prosthetic by the patient in their day to day lives. To address these issues and move towards a future of improved quality of life for patients who suffer amputations, Loughborough University formed the Next Generation Prosthetics research cluster. This work is one of four multidisciplinary research studies conducted by members of this research cluster, focusing on the area of Computer Aided Design (CAD) for improving the interface with Additive Manufacture (AM) to solve some of the challenges presented with improving prosthetic socket design, with an aim to improve and streamline the process to enable the involvement of clinicians and patients in the design process. The research presented in this thesis is based on three primary studies. The first study involved the conception of a CAD criteria, deciding what features are needed to represent the various properties the future socket outlined by the research cluster needs. These criteria were then used for testing three CAD systems, one each from the Parametric, Non Uniform Rational Basis Spline (NURBS) and Polygon archetypes respectively. The result of these tests led to the creation of a hybrid control workflow, used as the basis for finding improvements. The second study explored emerging CAD solutions, various new systems or plug-ins that had opportunities to improve the control model. These solutions were tested individually in areas where they could improve the workflow, and the successful solutions were added to the hybrid workflow to improve and reduce the workflow further. The final study involved taking the knowledge gained from the literature and the first two studies in order to theorise how an ideal CAD system for producing future prosthetic sockets would work, with considerations for user interface issues as well as background CAD applications. The third study was then used to inform the final deliverable of this research, a software design specification that defines how the system would work. This specification was written as a challenge to the CAD community, hoping to inform and aid future advancements in CAD software. As a final stage of research validation, a number of members of the CAD community were contacted and interviewed about their feelings of the work produced and their feedback was taken in order to inform future research in this area.

Atualmente a área de saúde vem buscando auxílio na engenharia para a contribuição no estudo e confecção de próteses para casos específicos de fraturas ou doenças ósseas. Com o avanço da tecnologia surgiram processos de manufatura que tornam possível a fabricação de próteses personalizadas. Uma dessas tecnologias é a manufatura aditiva. O grande desafio no momento está na fabricação de próteses por manufatura aditiva que combinem desempenho biomecânico e resistência estrutural. Nesse contexto, o objetivo deste trabalho é desenvolver elementos de fixação, especificamente âncoras de sutura de polímeros PEEK e PEKK, considerando seus requisitos estruturais através de simulações pelo método dos elementos finitos, e considerando que sejam fabricadas através de processos de manufatura aditiva. Este desenvolvimento permitirá a substituição de âncoras de sutura de liga de titânio, hoje largamente empregadas pelos cirurgiões, por âncoras de sutura de polímeros biocompatíveis, o que possibilitará que estes polímeros sejam absorvidos pelo corpo humano em curto e médio prazo, permitindo a completa restituição do osso afetado, melhorando a qualidade de vida do paciente pós-cirurgia. Os resultados obtidos neste trabalho indicam que a técnica poderá resultar em próteses com a biocompatibilidade desejada e resistência mecânica adequada. Próteses permanentes (articulações) ou provisórias (âncoras de sutura) seriam um dos critérios para a escolha do material a ser utilizado, absorvível ou não pelo corpo humano. / Nowadays medicine is searching assistance from engineering that may contribute in studies and confection of prothesis to specific cases of fractures and bone diseases. With the advance of technology new processes of manufacture were risen, making possible the confection of personalized prothesis. The biggest challenge of the moment is in the manufacture of additive prothesis that can combine biomechanics performance and structural resistance. In this context, the objective of this dissertation is to develop PEEK and PEKK polymer suture anchors, considering its structural requirements, taking into account their mechanical strength, through simulation by the finite element method, and considering additive manufacturing processes. This development will allow the replacement of titanium alloy suture anchors, now widely used by surgeons by suture anchors of biocompatible polymers, which enable these polymers to be absorbed by the human body in the short and medium term, allowing full regeneration of affected bone, improving the quality of life of the patient. The results of this study indicate that the technique could result in prosthesis with the desired biocompatibility and adequate mechanical strength. Permanent prosthesis (joints) or temporary (suture anchors) would be one of the criteria for the choice of material to be used, absorbable or non absorbable by the human body.