The work within this Thesis is concerned with the manufacturing processes associated with the production of blade root mounting slots in aeroengine compressor and turbine discs. Typically slots are of dovetail or fir-tree geometry dependent on specific design requirements. The state of the art process across the industry is broaching however, despite achieving required geometrical tolerances and surface integrity for decades the process is not without its disadvantages. Primarily these include the inflexibility of the process, machine tool cost; size and cutting forces, complexity of tooling and set up and further the limited level of control of the process beyond tooling design. This has led to research into alternative processes across a range of conventional and non-conventional manufacturing techniques. Work presented here focuses on two key technology areas, namely point grinding and electrolytic point grinding. The former applies small diameter single layer grinding wheels on a high speed machining centre with spindle capability in the region of 60,000rpm. Target geometry was a complex fir-tree root form requiring dimensional control to within +/- 5um and a surface integrity in line with critical aerospace components. The later process investigated the unification of point grinding and electrochemical machining on a vertical machining centre to assess process performance across a range of variables.

Microneedle arrays have been proposed for drug delivery and point-of-care diagnostics to improve the quality of health care delivery systems. Unskilled and painless applications of microneedle patches for blood collection or drug delivery are two of the advantages of microneedle arrays over hypodermic needles. Microneedle designs which range from sub-micron to millimetres feature sizes are fabricated using the tools of the microelectronics industry from materials such as metals, silicon, and polymers. However, to date, large-scale manufacture of microneedles has been limited because of the high cost and complexity of microfabrication techniques. This thesis aims to develop new manufacturing methods that may overcome the complexity of microneedle fabrication and scale-up problems. Three different microfabrication methods were investigated. (1) Silicon microneedles were manufactured through deep reactive ion etching (DRIE) with variable heights and tip sharpness. A series of experiments were also performed to investigate the influence of design and process parameters on the fabrication outcomes. (2) Plastic microneedle arrays were fabricated by three-dimensional (3D) printing. (3) A great variety of microneedle array geometries were manufactured using 3D laser lithography. The novel microneedle array design and fabrication technique proposed in this thesis may facilitate the manufacture of low-cost patches for drug delivery and collection of subcutaneous capillary blood or interstitial fluid.

As a part of the sign-off procedure for body and power unit mounted components, random vibration testing is carried out to original equipment manufacturer (OEM) specification which the components must survive without damage. With the current move to minimise design and development costs and time-scales in the development of new vehicles, the use of CAE to validate system design through the use of virtual testing is becoming ever more important. The desire is therefore to develop computer aided analysis/numerical techniques that will replicate the vibration testing of body and power unit mounted components. The research demonstrates the development of numerical analysis to replicate the vibration testing of a Diesel Engine EGR Coolant Rail. A Finite element model of the coolant rail with rubber hoses was developed. The rubber material properties were derived from a series of tests (tensile test, relaxation test and DMA test) and were modelled using visco-hyperelastic constitutive equations. In order to check the validity of the simulation results, a test rig was designed and developed. In this research, the influence of the fluid dynamics on the vibration of a mechanical structure is also presented using the FSI method. A FE analysis was conducted to simulate the vibration behaviour of an EGR coolant rail consisting of a metal tube and rubber tubes at both ends of the metal tube with water inside it. The correlation study suggests a close agreement between the test and simulation results in terms of the prediction of the natural frequencies. This analysis enables design engineers to extract the natural modes and frequencies of vibrating parts with flowing fluid in order to investigate the failure modes and redesign brackets, supports, and fittings for desired strength.

Finding solutions for increasing energy demands is being globally pursued. One of the promising solutions is the utilization of renewable forms of energy with thermo-mechanical conversion systems such as Stirling engines. Nowadays, effort is made in industry and academia to promote the development of Stirling technology. In this context, this thesis was first focused on modelling of High Temperature Difference (HTD) gamma-type Stirling engine prototype (ST05-CNC) and investigating means of improving its performance. Secondly, newly parallel-geometry mini-channel regenerators (with hydraulic diameters of 0.5, 1, 1.5 mm) and their test facility were developed and fabricated to enhance engine performance.

This project focuses on understanding and improving the technology used in the ceramic processing of the investment casting of orthopaedic implants. The shell making process is a time consuming and costly stage of the Investment casting process. This work reviews the use of a super absorbent polymer as a means to decrease lead time within the shell room and improve capacity. The technology allowed a typical shell which had 2 hours dry time to be reduced by 75% to 30 minutes between coats. Following initial analysis, a greater understanding on the flaws of the Rapid Shell system was sought. Work was also conducted to improve and understand the parameters which affect a generic shell system. Changes to the raw material were reviewed by changing the particle size of stucco and flour materials to improve strength. Different processing methods were also analysed to gain a better understanding into the fundamentals of ceramic processing. The use of rainfall and fluid bed stucco applications were analysed within a DOE experiment to better understand the effect of changes in microstructure affecting the overall performance of the shell. The results showed the microstructure varied greatly between processing method which in turn affected the thickness and strength of the respective shell systems. Rainfall sanded shells exhibited a thinner stucco layer while the flexural strength was 20% higher than fluid bed shells.

The research focused primarily on the effects of WEDM on the surface / subsurface integrity of Ti-6Al-2Sn-4Zr-6Mo titanium alloy and Udimet 720 nickel base superalloy, and encompassed measurement of surface roughness and contamination, workpiece microhardness, recast layer thickness, residual stresses and fatigue performance. Associated productivity and manufacturing costs were also evaluated in respect of blade root slot machining in aerospace turbine / compressor discs. Preliminary tests results showed that machined surfaces with Ra of ~0.5μm, less than 2μm of recast layer and almost neutral residual stresses were obtained following a roughing and four finishing passes. In a subsequent phase it was possible to reduce the number of finishing passes into only 2 while maintaining similar surface integrity figures, where also it was possible to wire machine firtree slots geometrical accuracy of ±7μm. This phase also entailed extensive assessment of the impact of pulse shape on surface integrity when using similar pulse energies. Fatigue performance tests proved no statistically significant differences between WEDM and flank milling at 5% level. The research also investigated the use of coated wires and oil based dielectric compared to standard brass wire and de-ionised water, where significant differences in productivity were recorded.

Focused ion beam (FIB) systems have been used widely in micro/nano technology due to their unique capabilities. In this fabrication technique, ions are accelerated towards the sample surfaces and substrate atoms are removed. Despite the ubiquity of this method, several problems remain unsolved and are not fully understood. In this thesis, the effects of FIB machining and its halo effects on substrate are investigated. A novel detector which can perform measurements of the current density profile of the generated beam, was successfully demonstrated. The effect of ion solid interactions for 30keV Ga FIB are investigated through atomic force microscopy (AFM) and Raman spectroscopy, for various machining parameters such as current, dwell time and pixel spacing. The FIB implanted regions were also studied for use as a hard mask in plasma etching, and was found to be suitable for high speed patterning in large area fabrication of nano-featured surfaces for metamaterials. It was observed by controlling the implantation parameters, the ultra-thin structures could be made. These structures have wide range of applications such as nano-scale resonators with application of chemical and biological sensing, membranes with nano-pores for DNA translocation and fabrication of near field optical devices.

This study aims to enhance the performance of the solar heater, consisting of parabolic dish concentrator and thermal receiver, as well as the expander, Small Scale Turbines SSTs. Using an advance ray tracing technique, OptisWorks software, both; a small scale parabolic dish concentrator and thermal cavity receiver were developed and optically enhanced. Simultaneously, small scale axial and radial turbines were developed using meanline approach and 3D CFD modelling using ANSYS CFX software. Then, the stator and the rotor of the SSRT were parametrized using two optimization techniques of multi-objective Genetic Algorithm optimization. To examine the SSRT mechanical design reliability, finite element analysis was utilised to determine the values and the locations of each; stresses, deflection and minimum allowed cycle number for the rotor. Consequently, to reduce the Von Mises stresses and deflections and increase the minimum number of cycles on both the rotor shaft and blades, multidisciplinary optimization was conducted to ensure better structural performance without influencing its aerodynamic performance. Comparing numerical and experimental, results showed that the maximum deviation in predicting the compressed air outlet temperature for the thermal receiver was less than 5%. Also, the deviation in SSRT efficiency and power output were about 16% and 14% respectively.

Regions with unimodal, bimodal and trimodal y\(^'\) distributions were created using selected heat treatments prior to mechanical testing. Effects of environment and test temperature on the high temperature mechanical behavior of this alloy have additionally been studied.

The microstructure and mechanical properties of direct laser deposited IN718 have been investigated and compared to forged IN718 base material (BM). Typical laser deposited microstructural features such as deposit layers, columnar grains and dendritic structures are observed in material addition (MA). Secondary phases such as γ’’, γ’, Laves phase, δ phase, carbides and α-Cr in MA are identified. Microhardness is measured throughout the deposit build - comparable hardness is obtained for both MA and BM. Tensile tests are carried out at room temperature and 600 °C for both MA and BM. Higher yield stress and lower elongation to failure are obtained when the loading direction is parallel to the deposit layers. Fatigue crack growth resistance tests at stress ratio of 0.1 and 0.7 have been carried out at 600 °C for MA. A higher threshold value and better fatigue crack growth resistance are found for crack growth direction perpendicular to the deposit layers. Both orientations in MA show higher threshold values and increased fatigue crack growth resistance to BM. Fractography and cross-sections after tensile and fatigue crack growth resistance tests indicate that layer interfaces, columnar grains boundaries and interdendritic regions are weak regions in MA.