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The civil aerospace industry is moving towards the 'more electric aeroplane'. The benefits are reduced weight and reduced maintenance which will result in better fuel economy and lower flight cost per mile. One of the important technologies is fault tolerant yet power dense electrical drive systems which have very high reliability to meet safety-critical aircraft applications. The particular subject of this thesis is fault detection in permanent magnet synchronous machines. The specific target application is a 16kW, 15,000 rpm aircraft engine fuel pump drive that has previously been developed by the Power Electronics, Drives and Machines Research Group at the Newcastle University.

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The primary aim of this study is to develop and validate a computer model for the design of pleated cartridge filters. Mathematical modelling of incompressible creeping flow and low permeability Darcy flow are well established and a number of reliable schemes for the simulation of these regimes are available in the literature. In the context of the present studies a computer model for modelling of combined Stokes/Darcy flows encountered in pleated cartridge filters has been developed. A two-dimensional simulation code that can model fluid hydrodynamics in permeable media as in dead-end pleated cartridge filters has been developed in FORTRAN. The developed code named as ACFAMP- Aircraft Cartridge Filter Analysis Modelling Program has been used to evaluate the performance and design of pleated cartridge filter elements. The governing equations of the flow model can be well represented by the Continuity, Stokes and Darcy equations respectively. Viscosity variations and non-Newtonian effects have been introduced to model the behaviour of shear-thickening fluids used in aircraft hydraulic circuits. The governing equations of the flow model are solved by using a weighted residuals finite element method. Two separate modelling approaches have been adopted in the model development. The first approach is based on modelling of flow through porous media by employing a slightly compressible form of continuity equation utilising nine-noded Lagrangian elements for domain discretisation in conjunction with a U-V -P finite element scheme. The second strategy is based on modelling of coupled Free/Porous regimes making the model industrially complaint. This scheme utilises the stabilised C0 continuous Taylor-Hood element, which generates stable solutions for incompressible flows without any problems of numerical locking. Initial numerical experiments were based on simple geometries and the complexity of the geometries was finally extended to model the pleated cartridge filters. A permeability model that interprets medium compression effects and which is based on data obtained from flat sheets of the filter material used in the fabrication of the filter cartridge is incorporated within the main model. During pleating, bending and creasing the medium deforms and leads to a loss of permeability and/or effective filtering area results. The combined effects of compression and reduction in filtration area cause deviations from Darcy's law. The effects of medium compression, pleat deformation and pleat crowding have also been analysed. The present work is directed towards the prediction of accurate values of compression factors and percentage losses in the filtration area, which assist in designing pleated cartridge filter elements. The simulated results have been compared against the experimental data for purposes of validation.

A selection of cleaning procedures are discussed which may be used to remove epoxide resin flash contamination bonded on metal and carbon fibre reinforced composite mould tooling that is used in the aerospace industry. Laser ablation, dry ice blasting and chemical cleaning using sodium hydride are three cleaning procedures studied in depth and have been used to treat a range of industrially sourced and model substrates, and contaminants. The effectiveness of the different cleaning regimes have been evaluated using Scanning Electron Microscopy, Atomic Force Microscopy, Auger Electron Spectroscopy, X-ray Photoelectron Spectroscopy and other analytical characterisation techniques. The necessity to clean aerospace tooling arises when moulded parts cannot be easily released from mould tooling and this is associated with mould release residues that have built up over a number of moulding cycles and eventually cause the moulding to stick. A comprehensive literature review of non-stick coatings is given and alternative mould non-silicone based release coatings are evaluated using the above analytical techniques. Coatings investigated include; fluoroalkylsilane, fluoropolymers and metal-fluoropolymer composites and the problems and merits associated with each are discussed.

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Research focused on the selective laser melting (SLM) of stainless steels and aluminium alloys. For steels, the possibility of creating a magnetically graded material was demonstrated as well as the ability to improve consolidation with austenitic and martensitic stainless steel powder mixtures. Stainless Steel/CoCr hybrid samples were also manufactured and tested to investigate the advantages of functionally graded materials (FGMs). Al alloy research began with examining the requirements for successful Al alloy consolidation in SLM and through experimentation it was found that Al alloys with good welding properties were the best choice: pure Al was found to be completely unsuitable. 6061 Al alloy was then used as a base material to manufacture Al-Cu alloy samples. Single layer SLM samples were produced first, which resulted in recognised Al-Cu microstructures forming. Multilayer Al alloy SLM research resulted in the discovery of the theorised ability to manufacture Al-Cu alloy parts with a nanocrystalline Al matrix with dispersed Al2Cu quasicrystals, resulting in a material comparable to a metal matrix composite that showed excellent corrosion resistance and compressive strength. Finally, a demonstration part was made to test the capability of the SLM process producing an aerospace type geometry using a customised Al alloy. Observations during manufacture and post process analysis showed that Al alloys were susceptible to changes in mechanical properties due to the geometry of the manufactured part.