Surface triangulation is an active area of research due to its wide usage in a range of different computer aided applications, including computer aided design (CAD), manufacture (CAM) and finite element analysis (FEA). Although these applications are used to create, interrogate, manipulate and analyse surfaces, internally they actually approximate the surface geometry using a triangulation and then operate on the triangles, making them triangulation dependant algorithms. However, despite the reliance on the triangulation by the downstream application, there is very little work which has been focused on the inherent affects of the underlying triangulation on the performance or result of the application. Therefore, the impact of the triangulation on the downstream application is still not well known or defined. This thesis investigates triangulation and the downstream effects on the triangulation dependant method of surface flattening. Two novel topics are explored, notably right angle triangulation configurations (RATCs) and axis of minimum principal curvature (AMPC) influenced triangulations, each which was found to have an impact on the triangulation dependant method of surface flattening. Right angle triangles (RATs) are commonly used throughout surface flattening. However, given a set of uniformly sampled points, there are many different ways in which the diagonals can be placed to form a final triangulation consisting of RATs. These different configurations of edges are introduced as RATCs. To investigate the effects of RATCs on surface flattening, three global configurations are proposed; regular, diamond and chevron. In addition, local variations of RATCs are explored by fitting RATCs that best approximated the local Gaussian curvature of the original surface. Also considered is the influence of triangulation developability and its effects on flattening. Developable surfaces should flatten without inducing any area or shape distortion. However, it is shown that the transfer of this developabilty information from the surface to the triangulation can be lost. It is established that skewing the vertices of a triangulation so that no triangle edges followed along the AMPC, causes the flattening to induce distortion. As the shape of a triangulation is defined by its edges, if no edges follow along the AMPC, this means that the triangulation will not inherit this shape characteristic. Therefore, a new method is proposed to triangulate a surface, whilst ensuring that one edge of every triangle follows along the general direction of the AMPC. This thesis also introduces a new efficient and robust parametric trimmed surface triangulation method. Efficiency is gained during trimmed curve tracing by minimising the number of cells processed. Key features are the efficient tracing algorithm and knowledge of orientation of the trimming curves is not required. This approach also minimises the occurrence of degenerate triangles and copes with holes independently of the grid size.

The combustion and emissions performance of oxygenated fuels has been investigated in a modern direct-injection spark-ignition (DISI) engine. In particular, the new biofuel candidate, 2,5-dimethylfuran, otherwise known as DMF, has been assessed as a future automotive fuel against ethanol, the most commercially accepted spark-ignition (SI) biofuel. When operating with DMF, the engine performance and emissions are less sensitive to changes in key control parameters than with gasoline. This allows a wider window for improving performance and/or reducing emissions. The relevance of modern injection strategies to increase performance or efficiency has also been assessed when using DMF. The use of split-injection at full load is shown to be less beneficial than with gasoline. Novel fuel preparation techniques have been investigated by comparing externally supplied gasoline-biofuel blends (conventional method) to internally mixed, dual-injection blends. This new mode presents an avenue for optimising oxygenated fuels with a low heat of vaporization, such as DMF and n-butanol; low blends with gasoline (≤25% by volume) are more efficiently utilised than in external blends. Furthermore, the particulate matter (PM) emissions can be reduced with dual-injection because gasoline is supplied through PFI. The unlegislated emissions when using DMF have been benchmarked against gasoline and compared to other oxygenated fuels. In particular, the emissions of the major carbonyls are lower when using DMF compared to gasoline and even less so than ethanol, which heavily emits acetaldehyde and formaldehyde. The dual-injection mode further reduces the total carbonyl emissions when using DMF and ethanol blends compared to direct-injection (DI).

The static and dynamic properties of carbon fibre composites of varying orientation, stacking sequence and geometry has been analysed in terms of modulus and material loss factor up to strain rates applicable to golf club shafts. No noticeable change in modulus or damping was seen at strain rate applicable to golf club shafts. All panels tested strain rate sensitivity onset occurred at around 0.4 s\(^{-1}\), which is above the maximum observed during a golf swing (0.1 s\(^{-1}\)). The strain rate sensitivity was found to be sensitive to aspect ratio (for strain rates above 0.4 s\(^{-1}\)). Two 20° panels of the same fibre interfacial area, but with different aspect ratios (length/width) showed different strain rate sensitivities. The short wide panel (aspect ratio 1.5) showed a higher stiffness and lower strain rate sensitivity when compared to a panel with an aspect ratio of 2.6. A model was created to predict the modulus and damping of lay-ups for laminates and golf club shafts. The model was validated against three composite systems at varying orientations and stacking sequences. The software agreed well with laminate experimental data (data sets showed a RMSD of less than 5 %). From this an optimising software was developed to provide the user with a stacking sequence that will optimise modulus, damping or the product of both. This thesis also evaluated commercial shafts in order to determine the models applicability to this application. Commercial shafts were tested for both stiffness and damping, where a number of aspects such as inter-ply resin rich regions and seam were observed as possible areas for discrepancy with the models prediction. Shafts were fabricated in order to analyse these aspects in greater deal, and to determine the models limits for this application. The model accurately predicted the stiffness of the shafts however the model failed to predict the damping of the shafts when comparing to the average values taken. When damping was compared to the areas where no seams were present, the model agreed well except for in two cases, which have been attributed to shafts flaws (cracks or excess inter ply resin). The model presented in this research consistently characterised the stiffness of fabricated shafts, however the seams proved too dominant a feature to be neglected in the prediction of damping.

Shot peened steel tubing made from 304HCu-grade austenitic stainless steel was exposed to temperatures of 600-750°C in three atmospheres: vacuum, deoxygenated atmospheric pressure steam and deoxygenated 70bar steam. The microstructural changes and oxide morphologies of the shot peened material were observed with SEM, TEM, microhardness testing and TKD mapping. An estimate of the lifetime of the shot peened microstructure in service conditions was made based on service temperature. MnCr2O4 spinel was observed on oxidized samples and the consequences of this are discussed.

This PhD project is set out to study the mechanism of gigaseal’ formation and to provide techniques which enable the frequent formation of high resistance seals. Such techniques are highly desirable at both research and industrial levels. The research can be divided into three main sections. In the first section the most important factors in seal formation were identified. Then a group of novel approaches have been developed to alter these factors and achieve better sealing conditions. In the second section the effect of roughness, hydrophilicity and tip size on gigaseal’ formation has been studied. Patch clamp experiments were carried out using conventional and treated pipettes. In the third section of this research, glass micropipettes were characterized using various measurement techniques. The proposed techniques in this thesis not only explain the gigaseal formation in more detail, but also provide techniques to increase both the seal resistance and probability of seal formation. FIB polished pipettes improved the seal resistance significantly and chemically treated pipettes resulted in the formation of seals for more than 80% of trials. Therefore the research aims have been successfully met.

Following an extensive literature survey focusing on the machinability of carbon fibre reinforced plastics (CFRP), three main phases of experimental work were undertaken to evaluate the drilling of CFRP and associated stack materials. Phase 1 and 2 involved small diameter holes (1.5 mm) in thin CFRP laminates (3 mm thick) while Phase 3 addressed the feasibility of one-shot drilling (6.35 mm diameter holes) in multilayer workpiece stacks comprising titanium, CFRP and aluminium. Machinability was assessed in terms of tool life/wear, force/torque, hole size and geometrical accuracy, workpiece surface integrity and chip morphology.

Understanding the influence of the fabrics microstructure on frictional noise was investigated in terms of surface roughness for three multi-fibre apparel fabrics (denim, cotton and silk) and single-fibre polyester model fabrics. Surface roughness (R\(_a\)) correlated strongly with total noise emitted (R\(^2\) = 0.97) and was attributed to the ‘hairy’ nature of multi-fibre fabrics. In terms of specific frequencies emitted within a fabric’s sound spectrum, the microstructure of the model fabrics was strongly correlated (R\(^2\) = 1.00) with the fundamental harmonic predicted, enabling a ‘fingerprint’ theory to be proposed. Friction coefficients, measured using tribology, of apparel and model fabrics were established, and showed that the major impact on friction was R\(_a\) and fibre type. Furthermore, friction was reduced via the lubrication of hydrocolloid fluid gel particulates, by means of reducing the surface roughness by filling in asperities and reducing the hairy nature of the fibres. Consumer perceptions of fabrics and fabric sounds were established with one-to-one interviews, and the influence of sound on sensory perception and liking was established by manipulating real-time fabric sounds, showing that by altering high and low frequencies, and overall noise, a significant difference in sensory attribute 'textured' can be observed.

Friction Stir Welding (FSW) is a suitable technology for aerospace structure development and is a possible replacement for mechanical fastening. To achieve the application of FSW, pre and post-weld treatments are required. A pre-weld treatment of surface preparation was required to ensure a weld with good mechanical properties. The surface preparation necessary is the removal of paint and anodising layers from aerospace alloys. Laser paint removal was assessed and designed to remove these layers with only an oxide remaining, which welded to produce high quality welds. The post-weld treatment was essential to increase the corrosion resistance of the welded area. The improvement in corrosion resistance was achieved with High Power Beam Surface Modification (HPBSM), which created a homogeneous surface through rapid surface melting and solidification. The rapid thermal processing dissolved and dispersed the precipitate solute atoms which were retained in solid solution through planar solidification. Electron beams and various lasers were used in the HPBSM processing. Excimer Laser Surface Melting (LSM) improved corrosion resistance but the layer depth was restricted by processing parameters. HPBSM processing studies using an electron beam, USP-CO\(_2\) laser and Nd:YAG laser provided understanding on how processing parameters controlled the modified layer characteristics.

An investigation has been carried out into the mechanisms of failure of silica bonded investment casting moulds, with the aim of reducing failure rates for larger components. The analysis begins with a detailed microstructural examination of a current commercial mould system using scanning electron microscopy and other allied analysis techniques. The mould structure is shown to be nonuniform and unpredictable, with poor packing of the ceramic constituents leading to a non-uniform porosity network. The structure and distribution of the binder is also established and this indicates that the major load bearing points within the mould consist of thin areas of silica. As such, the overall performance of the mould is directly related to that of the silica itself. This binder is shown to contain impurity elements leached from the ceramic filler at various stages during mould manufacture. These elements alter the phase composition and thermal properties of the binder. Mould temperature profiles for a range of casting sizes have been measured and used to illustrate the relationship between metal weight and maximum temperature attained within the mould section. The profiles are also used to investigate the creep response of silica based binders. It is found that a combination of high temperatures and creep within the silica phase is responsible for the casting defects found with larger components. From these observations, a prediction is made regarding failure mechanisms and suggested remedial action. The thermal properties of several commercial water based binders are evaluated and the suitability of each as an alternative binder is discussed.

A knowledge of the flow occuring in metal-forming processes is of great industrial importance, and the finite-element technique is the only form of deformation analysis which can predict the flow of the material. The examination of forging operations requires a full elasticplastic treatment to be used. This thesis is concerned with an elastic-plastic, finite-element program which has been developed to investigate three-dimensional examples of this process. The fundamental theory of the finite-element method is first introduced, and then the finite-element program is described in detail. The deformation, and distributions of hardness and die-interface pressure, predicted by this technique for the unlubricated upsetting of a rectangular block are compared with experimental results, and found to be in broad agreement, the differences being attributed to the incorrect imposition of very high friction by the friction-layer technique used in the analysis. With a corrected form of the friction technique, the finiteelement program predicts results for the axisymmetric friction-ring test and a new three-dimensional friction test which are in good agreement with experimental findings up to deformations of approximately 30%; the friction-layer technique used successfully in previous axisymmetric treatments appears to be unsuitable for threedimensional formulations when large deformations are considered. The finite-element program developed here is shown to be capable of modelling an example of a more complicated three-dimensional forging, that of an automobile connnecting rod. The experimental measurements of cteformation and hardness for an aluminium con rod forged using graphite lubrication are found to be in good agreement with the finite-element predictions obtained assuming sticking friction conditions but not with the results of a zero-friction idealisation. Finally, suggestions are made for the future development of this technique.