Many foods contain large amounts of saturated fatty acids (SaFa), which are considered unhealthy, and their presence in the diet is one of the contributing factors of cardio-vascular disease, obesity and the inherent risk of diabetes. It has become the driver of food producers to manufacture products with as little of these oils as they can. Reformulation work based on Elmlea whipping creams sought to address this issue, by which the ingredients of the principal formulation were taken and ever increasing levels of liquid oil were added, but keeping the total oil concentration at 34%. Many of its’ properties were tested and the optimum formulation was found to be that containing 20% hydrogenated and 14% liquid oil. Further formulation work was associated with another product: ice-cream. Ice-cream distribution, particularly with its transport over the Rocky Mountains in the US, poses a large problem. Taking ice cream across the Mountains involves travelling at altitudes in excess of 2000 metres and this leads to its expansion due to the reduced air pressures. The product can spoil in transit. Further instabilities arise when extruded from a freezer. This instability was studied extensively in this work. It was seen that larger drops in pressure and at a slower rate were more detrimental to the model foam structure than small pressure differences and a fast rate. The fast pressure release seemed to have less of a detrimental effect on the resultant bubble foam microstructure.

The present investigation has been focused on the design, deposition and characterisation of novel low-friction, wear-resistant multilayer nanocomposite CrAlTiCN coatings. Systematic materials characterisation and property evaluation were conducted on the as-deposited and oxidation-tested CrAlTiCN coatings, and the results are presented and discussed. It is possible to generate novel CrAlTiCN coatings with the carbon content up to 24.34 at% by closed-field unbalanced magnetron sputtering of graphite target. The microstructure of the CrAlTiCN coatings mainly depends on their carbon content. When the carbon content is low, carbon atoms are mainly dissolved in the fcc metastable phase (Cr, Al, Ti) (C, N); when the carbon content is high, the major carbon atoms will form amorphous carbon with a C-C bond state and in a sp\(^2\) dominated graphitic environment. Both the hardness and brittleness of CrAlTiCN coatings reduce with increasing the carbon content. When tested at room temperature under unidirectional sliding conditions, the friction coefficient and wear of the CrAlTiCN coatings decrease with the carbon content, and the thermal stability of CrAlTiCN coatings is similar to the CrAlTiN coating but better than graphite-like carbon coatings. The good performance of the new CrAlTiCN coatings can be attributed to the optimised design of the coating system: the Cr/Al for oxidation resistance, the amorphous C for lowfriction and the multi-layered nano-composite microstructure for high toughness.

Ultrasonic metal welding (USMW) has received significant attention in the past few years, and has become more reliable and suitable for a wide range of applications. In recent years, the technique has been extensively used due to the advent of component miniaturisation and improvements in producing lightweight components. There are a number of advantages for USMW, including greater efficiency and speed, longer tool life, higher accuracy and no filler or flux needed to be used. Thus the technique can be viewed as being environmently friendly. However, the technique is not inexpensive, primarily due to the high cost of welding tools. Therefore, the design and construction of a lateral-drive USMW system which is capable of joining thin metals is presented in this thesis. The fundamental aspect of this study is the design of an integrated spot welding horn, along with other welding components such as a stationary anvil, mounting holder, welding bed, as well as the relevant fixing tools and fixtures. High precision is required in the design of the components, and in particular the welding horn. Because the horn is responsible for transferring energy to the welding zone, specimens must be prevented from sliding during the joining process, and an appropriate clamping force must be applied which will ensure acceptable bonding. Many criteria have been examined to enhance the performance of a working horn. The horn excitation frequency has been matched to the transducer frequency, ensuring that the horn will be vibrated longitudinally close to 20 kHz, thereby allowing the tuned mode to be isolated from other non-tuned modes, which guarantees uniformity of the vibration amplitude at the horn working surface, high gain factor of 4.108, and the avoidance of any stress initiated at the points between connecting components. Examining of these criteria is essential in order to optimise the excitation of the horn and to transmit the energy with minimum dissipation. The analytical studies and the finite element (FE) modelling of the welding components were successfully simulated, from which the vibrational behaviour and dynamical characteristics of the system were precisely verified using experimental modal analysis (EMA). The welding stack (the horn connected to the transducer), welding components and fixtures were then set-up on the driving machine. The device was examined prior to welding to ensure the excitation at high vibration. Many tests were successfully conducted on the welding together of aluminium and copper in a number of different configurations using the ultrasonic metal spot welding system. Weld strength and quality were shown to depend on complex relations of process parameters such as clamping force, amplitude of vibration, welding time and input power. A series of weld combinations with different thicknesses and ii variations in metal conditions were studied. The results of the lap tested specimens suggest that the bond strength is sensitive to the relationships between clamping force and vibration amplitude. Overall, the weld strength results suggest that the Al-Al welds are stronger and more consistent in terms of weldability than the Cu-Cu welds. In the welding of dissimilar metals, stronger welds are produced when the aluminium specimen is placed on top and in contact with the horn tip, rather than the copper. The thickness and surface condition of the metals such as hardness, surface roughness and oxides, are significantly affect the weld strength. In welding of Al-Cu or Cu-Al, an increase in energy and time was necessary to generate an acceptable bond. The use of stepped amplitude profiling results in a pronounced increase in the weld strength improves consistency and enhances weldability. However, horn tip/specimen adhesion and specimen marking did not occur under certain conditions. The results of the FE simulation and experimental tensile tests, for the load displacement curves profiles, allow for good estimation of the maximum load and therefore weld strength. Weld quality of aluminium and copper specimens were observed through investigation of the deformed surfaces using Nomarsky optical microscopy and scanning electron microscopy (SEM). The results illustrate that good quality welds can be achived by joining specimens, regardless of the surface condition of the metal. The SEM confirmed that no mixing occurred by melting or fusion between intimate surfaces, which indicates that USMW occurs due to adhesion and cohesion mechanisms. Furthermore, xray diffraction confirms the percentage of morphology between Al and Cu, which indicates that largest weld formations are prevalent for those specimens that are softer and lower in hardness and surface roughness, regardless of the type of tempering.

The research addresses the topic of design for assembly from an aerospace structures perspective. Aerospace assembly has traditionally taken secondary important to aircraft performance. This approach has been validated through healthy sales, most recently demonstrated in the Single Aisle market. However, in recent times, design for assembly has become more important. There are two main drivers behind this shift in focus. The first is a desire from aircraft manufacturers to maximise profits on existing aircraft orders through redesign. The second is the future outlook of aircraft sales, estimated to be in the trillions of dollars 2035. Aircraft manufacturers have therefore recognised that optimising their manufacturing system is critical lest market share is lost to emerging aircraft manufacturers through an inability to meet rising demand. Three methods are then developed to provide design for assembly indicators for development decisions. The underpinning methodology behind these methods is a data driven approach. This is that cost saving decisions can be made using the mass of existing available data from production systems at early stages provided that key indicators are identified. The methods allow engineers to make informed decisions on design for assembly and technology development. The first method addresses the issue of redesign. A tool is presented that relies on available data of assembly processes to make recommendations on redesign projects. The method is populated with real data and its output is compared against real business decisions. The results show that the method provides positive direction and is beneficial when filtering between costly redesign projects. The second method addresses design for assembly at early product development. A complexity metric is developed using a combination of historical data and known data at a particular development stage to produce a complexity metric that carries out an analysis of a full assembly system. It provides the engineer with a macro view enabling the identification of potential bottlenecks. Data from a previous product was used to demonstrate this method. The results shown were able to highlight real issues and make recommendations about technology strategy. The final method developed in this research recognised that design for assembly and assembly technology were synergetic and should be developed together. It proposed an assembly process characterisation technique to enable future technology strategy planning at design for assembly stage. The tool was demonstrated using existing data and proposed several concepts for a future product to enable higher levels of automation and more cost effective future technology implementation. The research concluded that there was a definite advantage in using the demonstrated methods in providing direction to an aircraft manufacturing business. In the redesign method and the complexity analysis method this was validated through comparison against real business decisions. The two methods were in line with business thinking. Also, where the redesign method was different in its advice compared with business direction, it was shown that following the advice of the method would have been beneficial to the business. It was more difficult to validate the shared platform approach method due to its results providing indicators for future decisions. Early analysis into its potential validity through technology benchmarking looked promising.

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This thesis investigates the feasibility of establishing a generalised approach for defining similarity metrics between 3D shapes for the casting design problem in Case-Based Reasoning (CBR). This research investigates a new approach for improving the quality of casting design advice achieved from a CBR system using casting design knowledge associated with past cases. The new approach uses enhanced similarity metrics to those used in previous research in this area to achieve improvements in the advice given. The new similarity metrics proposed here are based on the decomposition of casting shape cases into a set of components. The research into metrics defines and uses the Component Type Similarity Metric (CTM) and Maximum Common Subgraph (MCS) metric between graph representations of the case shapes and are focused on the definition of partial similarity between the components of the same type that take into account the geometrical features and proportions of each single shape component. Additionally, the investigation extends the scope of the research to 3D shapes by defining and evaluating a new metric for the overall similarity between 3D shapes. Additionally, this research investigates a methodology for the integration of the CBR cycle and automation of the feature extraction from target and source case shapes. The ShapeCBR system has been developed to demonstrate the feasibility of integrating the CBR approach for retrieving and reusing casting design advice. The ShapeCBR system automates the decomposition process, the classification process and the shape matching process and is used to evaluate the new similarity metrics proposed in this research and the extension of the approach to 3D shapes. Evaluation of the new similarity metrics show that the efficiency of the system is enhanced using the new similarity metrics and that the new approach provides useful casting design information for 3D casting shapes. Additionally, ShapeCBR shows that it is possible to automate the decomposition and classification of components that allow a case shape to be represented in graph form and thus provide the basis for automating the overall CBR cycle. The thesis concludes with new research questions that emerge from this research and an agenda for further work to be pursued in further research in the area.