The current methods for manufacturing super-abrasive elements result in a stochastic geometry of abrasives with random three-dimensional abrasive spatial locations. This thesis covers the laser generation of novel micro-cutting arrays in ultra-hard super-abrasive composites (e.g. polycrystalline diamond, PCD and polycrystalline cubic boron nitride, PCBN). Pulsed laser ablation (PLA) has been used to manufacture repeatable patterns of micro cutting/abrasive edges onto micro structurally different PCD/PCBN composites. The analysis on the influence of microstructural factors of the composite materials in the use of laser ablation technology has been carried out via a novel technique (Focused Ion Beam/High Resolution Transmission Electron Microscopy/Electron Energy Loss Spectroscopy) to identify the allotropic changes occurring in the composite as a consequence of PLA allowing the laser ablated PCD/PCBN surfaces to be characterized and the nanometric changes evaluated. The wear/failure characteristics/progression of the ultra-hard laser generated micro cutting/abrasive arrays has been studied in wear tests of Silicon Dioxide workpiece shafts and the influence of the microstructural factors in the wear properties of the super-abrasive micro cutting edges has been found. Opposing to these highly-engineered microcutting/abrasive arrays, conventional electroplated abrasive pads containing diamond and CBN abrasives respectively have been chosen as benchmarks and tested under the same conditions. Contact profiling, Optical Microscopy and Environmental Scanning Electron Microscopy have been employed for the characterization of the abrasive arrays/electroplated tools before/during/after the wear/cutting tests. In the PCD abrasive micro-arrays, the type of grain and binder percentage proved to affect the wear performances due to the different extents of compressive stresses occurring at the grain boundaries. In this respect, the micro-arrays made of PCD with mixed diamond grains have shown slower wear progression when compared to the electroplated diamond pads confirming the combination of the high wear resistance typical of the fine grain and the good shock resistance typical of the coarse grain structures. While PCD laser manufactured arrays indicated edge break as typical wear mechanism, the abrasive pad confirmed flattening of grits as main wear mechanism. Mixed grained PCD arrays performed 25% better than fine grained arrays. The improved wear performances of laser manufactured arrays when compared to industrial benchmark is proved by the different wear failure mechanism in the array and in the electroplated pad: in the first one the edges break creating new sharp edges during testing, while in the latter grit flattening is the main wear mechanism. This increases up to 60% the life of the laser manufactured array when compared to the benchmarked pads. As for the PCBN abrasive micro-arrays, two are the main wear mechanisms experienced by the arrays: edge flattening for the high CBN content array and edge breaking for the medium CBN content array. The wear performance of the high content PCBN array is directly comparable to the electroplated boron nitride pad, because they both worn out with edge/grit flattening. The increase of metallic binder and the presence of metalloids in the medium content-CBN specimens have shown to produce higher contact pressure with the workpiece when compared to the electroplated specimen, causing fracturing as the main wear mechanism; while the PCBN micro-array with purely a metallic binder phase has shown better wear performances and lower contact pressure in comparison to the electroplated CBN specimen. In particular, the laser manufactured array proved to perform 50% better than the electroplated ones in terms of wear resistance. Among all of the tested arrays, the mixed grained PCD and the purely metallic binder phase PCBN micro-arrays have shown slower wear when benchmarked to the electroplated pads, giving a possible application of their use in the cutting tool industry.

TWIP (Twining Induced Plasticity) steel is very promising AHSS (Advanced High Strength Steel) grade owing to its superior toughness and ductility. Recently it has attracted the interest of the automotive and steelmaking industries, as the need for reducing weight to provide better fuel efficiency is of paramount importance with the gradual depletion of fuel resources. A high Al, TWIP steel is being commercially developed as Al has been found very well in delaying fraction in deep drawn products. However these steels are difficult to continuous cast and cracking can occur at the slab surface. Therefore it becomes very important to gain an understanding of the cause of this cracking, in order to prevent their occurrence. To assess the likelihood of the cracking in these high Al TWIP steel slabs (1~1.5%Al, 0.6%C, 18%Mn), conventional hot tensile tests were performed to simulate the continuous casting process. A variety of TWIP steels were tested in order to determine the influence of such factors as chemical composition, cooling rate and thermal cycle on hot ductility. Using a cooling rate of 60oC/min after heating to 1250oC, ductility was generally <40% RA (Reduction of Area) indicating that these high Al TWIP steels it will be difficult to cast without transverse cracking occurring. The 1.5%Al containing steels had worse ductility than the low Al containing steels (0.02%Al) because of the presence of large amounts of AlN precipitated at the austenite grain boundaries. Reducing the Al and N level improved ductility. Higher strength Nb/V high Al containing TWIP steels were also examined although ductility was likely to be worse than the simpler microalloying free TWIP steels as was confirmed. Increasing the cooling rate from 60 to 180oC/min after melting caused the ductility to further deteriorate and high N levels produced only a small reduction in the ductility, probably because ductility is so poor. Increasing the S level from 0.003 to 0.01% caused the ductility to deteriorate in TWIP steels free of microalloying. Increasing the S level to 0.023% caused no further deterioration in ductility even though the MnS volume fraction increased. The worse ductility in the higher S steels was not caused by a simple increase in the sulphide volume fraction but more a consequence of the change from coarse hexagonal plate AlN, which are mainly within the matrix and so have little influence on the hot ductility, to very long dendritic rod precipitates, which are situated at the dendritic or close to the austenite grain boundaries. This dendritic precipitation was rarely observed in the low S steel. The MnS inclusions appeared to act as nucleation sites for the precipitation of AlN and when there was few inclusions precipitation of AlN was mainly confined to the matrix. The ductility of Nb containing high Al, TWIP steels was very poor in the as-cast condition. Adding B and Ti still gave rise to extremely poor ductility when a cooling rate of 60 oC/min was used but reducing it to 12oC/min caused the ductility to improve so that RA values were now close to the 35~40% RA value required to avoid transverse cracking. To improve ductility B and Ti additions were examined. 0.04%Ti and 0.002%B are required to ensure good hot ductility in high Al, TWIP steels. Sufficient Ti is needed to remove all the N as TiN so preventing AlN precipitating as films over the austenite grain surfaces. B is also needed as it can segregate to the boundaries and strengthen them. A SIMS technique confirmed that B had indeed segregated to the boundaries. The slower cooling rate 10~15oC/min compared to 60oC/min will result in the optimum segregation of B as well as coarsening the TiN precipitates so they are no longer effective in reducing the ductility. Following all these recommendations, i.e. a low S level, slow secondary cooling rate, a Ti level above the stoichiometric for TiN and a boron addition of 0.002%, transverse cracking was avoided commercially in these very difficult to cast high strength TWIP steels.

Fibre optic sensors have been developed extensively over the past several decades, showing their potential and suitability for real-time measurement and thus meeting various industrial challenges. This has been achieved through the continuous innovation both in the fibre structural design and in the exploration of a variety of sensing mechanisms employed. Optical fibre sensors have shown advantages over conventional electrical counterparts by being of small size, immunity to electromagnetic interference and resistance to chemical attack, thus revealing their potential for a range of industrial applications. High-birefringence (Hi-Bi) optical fibres represent an important type of specialist fibres that have been explored widely by researchers. The focus of this thesis is to explore their potential for different sensing applications as the birefringence of these polarization maintaining (PM) fibres varies in response to the change in the surrounding environment, such as force and pressure. Extensive evaluation of high-birefringence optical fibres, such as those with an elliptical core or elliptical inner cladding, Bow-Tie, Panda and Hi-Bi Photonic Crystal Fibres (PCFs), has been made both experimentally and theoretically, using numerical or analytical techniques. In this thesis, the material birefringence of Polarization-Maintaining fibres, e.g. PM side hole fibre(s) with one or two hole(s) located in its cladding, is calculated using a thermo-elastic displacement potential method through the superposition of sectional displacement potentials. These PM fibres have shown the potential for pressure/force measurement based on their birefringence characteristics when exposed to a transverse force. The methodology used is generic and thus applicable to any one-hole fibre structures, should the hole diameter or position vary in the fibre cladding, or the fibre hole be empty or filled in with any material. This enables the analysis to be applied more widely in a range of optical fibre sensor applications. Direct measurement of transverse force through the interrogation of induced birefringence variation has also been investigated in this thesis by using two specialist single mode Polarisation-Maintaining (PM) side-hole(s) fibres and four different types of Hi-Bi and low-Bi PCFs. The variation in the pressure sensitivity of these PM fibres has been investigated both theoretically and experimentally and it was confirmed that they are dependent upon several key parameters of the system, including the fibre structure, the magnitude and the direction of the applied external force, the fibre length used and the birefringence of the fibre. The theoretical data obtained have shown a good agreement with those from experiments, confirming the suitability of the use of such PM fibres for the measurement of pressure, force and mass of an object, applied in different directions, over a wide range and in real time. It is concluded based on the theoretical and experimental data obtained that PCFs of low birefringence are more sensitive than those of high birefringence (Hi-Bi) although the former require a longer length to achieve a similar level of birefringence. Compared to conventional Hi-Bi fibres (e.g. Panda and Bow-Tie fibres), PCFs have demonstrated much lower temperature sensitivity and this suggests that they are well suited to measure pressure, force, and mass in real time when temperature varies by using a fibre loop mirror (FLM) configuration. To solve the length problem in the low birefringence PCFs, a joint PCF approach can be used by fusion-splicing a short length of Low-Bi with a short section of a Hi-Bi PCF and their sensitivity to lateral pressure has been investigated and reported in detail in this thesis.

The topic of this thesis is mesoscale mechanics analysis of textile composites. The need for such analysis originates from the need to accurately predict structural performance of textile composite structures, which is known to vary as a function of textile geometry parameters. Because of textile composites' suitability for use in large deformation forming methods, modelling of yarn geometries and their deformation mechanisms have seen much developments in recent years, in particular, the development of dedicated CAD modelling tools like TexGen. The work in this thesis was started to devise automatic mechanics modelling of textile composite geometries, which was achieved by avoiding the generation of a mesh that follows yarn boundaries and instead assigns properties to integration points using textile querying implemented in TexGen. The conceptual advantage is that in such a method any additional effects (like prestress, initial damage or voids) can be added without adding geometric complexity. The effect of spatial averaging on the convergence of relevant outputs is analysed and a case study on a simple plain weave textile is presented. Good correlation of experimental and modelled strength was found and parametric studies on the textile geometry show that the range of strengths found in tests could be explained by the effects of geometric variables. More importantly, a practical automatic link between TexGen and FE analysis is implemented and demonstrated to work.

On complex systems with built-in health management systems, the faults diagnosed during a mission can number in the tens of thousands. When these faults are evaluated, many are found to be false. This work has, therefore, developed a technique by which diagnosed faults can be evaluated using known system data and a system modelling technique to automatically verify their legitimacy. Petri nets (PNs) were selected as the modelling technique since they allow systems to be modelled in a componentistic and flexible way, that still provides a high level of accuracy. The PN technique was used to model the performance of an experimental facility, the BAE Systems fuel rig, which represents an aircraft fuel system. A wide range of faults were injected into the system and sensor outputs were recorded. By comparing the sensor outputs from the fuel rig to the PN predicted system behaviour, the faults were assessed as either genuine or false. The standard deviation technique is used as part of the comparison process as it provides a high level of detail with low computational requirements. A piece of software was written to automate the PN simulation and comparison of the output data. The ability of the overall technique to verify diagnosed faults was demonstrated by a thorough consideration of failure modes in the fuel rig system. First and second order faults were evaluated and the results showed that the technique was very successful at identifying both genuine and false faults. Some issues were evident when hidden failures were considered and faults which were revealed for only short periods of time were injected. The PN technique was also successfully used to model the behaviour of the fuel system of the Airbus A340 aircraft. This system contains a higher level of complexity in terms of both design and operation compared to the fuel rig. The behaviour of the system in normal operation was modelled to replicate that described in literature and a number of first and second order faults were modelled. The PN predicted behaviour of the fuel system in the presence of these faults matched well with that expected. The PN technique can be used to obtain the output of sensors when failures occur, and such information can be used in the process of system design. An approach is presented by which a sensors value can be calculated and used to select sensors in a system. The technique considers the change in the value measured by a sensor as a result of faults for single sensors and their pairs.

As a strictly two-dimensional carbon material, graphene has attracted great interest in recent years due to its unique mechanical, electrical and optical properties. Currently, the principal methods for mass production of graphene are focused on the solution-based chemical redox reaction. The oxidation of graphite introduces a large amount of oxygen functional groups attached onto its basal plane or edges, which makes graphene oxide (GO) sheets hydrophilic to form stable aqueous colloids. However, the raw material graphite gradually becomes an insulator during the oxidation process as part of planar sp2-hybridized geometry transformed to distorted sp3-hybridized geometry, which loses its excellent electronic properties. As a result, reduction of GO is definitely necessary to recover its “lost” electrical conductivity for practical applications. In addition, the hydrophilic property of GO sheets allows metal oxide (MO) nanoparticles (NPs) anchoring on reduced graphene oxide (rGO) plane to fabricate MO/rGO composites with excellent electrochemical performance. However, the current preparation methods for the electrical conductive MO/rGO composites are very complicated which might have negative effects on the properties and hinder mass production. The objective of this project is to synthesize aluminium oxide (Al2O3)/rGO nanocomposites via oxygen annealing without using an Al2O3 precursor. This method establishes a very simple and efficient way to yield Al2O3 NPs on rGO plane by filtering GO dispersion through an Anodisc membrane filter with oxygen annealing, which is named oxygenally reduced graphene oxide (OrGO). The characterizations reveal that the Al2O3 NPs are formed exclusively on the edges of defective regions with uniform particle size less than 10 nm. As for the electronic properties, OrGO has a higher electrical conductivity at 7250 S m−1 with a narrower range of the electrical conductivity mostly between 6500 and 7250 S m−1, which can be due to the increase of the sp2/sp3 carbon ratio caused by the formation of Al2O3 NPs at the edges of defective regions in OrGO plane. Moreover, the formation of Al2O3 NPs maintains OrGO sheets with good hydrophilic property with a contact angle around 71.5°. The electrochemical performance of OrGO paper fabricated as electrode materials for lithium-ion batteries (LIBs) is also investigated. OrGO electrodes exhibit a high specific charge and discharge capacity at 1328 and 1364 mAh g−1. The cyclic voltammograms (CV) performance reveal that the insertion of Li+ ions begins at a very low potential around 0 V vs. Li+/Li while the extraction process begins in the range of 0.2–0.3 V. In addition, the OrGO electrode has excellent rate capability and cycling performance. The average coulombic efficiency (CE) was measured at 99.608% for 30 cycles, indicating a superior reversibility of the Li+ ion insertion/extraction process.

This thesis concerns a study including testing, analysis and design on beam-to column connections for the frames of pultruded glass fibre reinforced plastic profiles. The research consists of the two principal aspects of a laboratory test programme to determine connection behaviour and the formulation of a plane frame analytical tool to determine the effect of real connection on frame behaviour. The laboratory tests involved three different 10 inch beam-to-column connections which can be categorised as having a moment-rotation behaviour that is pinned. These connections had web cleats and the method of connection was by bolting, or bolting combined with adhesive bonding. The test configuration had a central column and two beams in a cruciform arrangement. Loading was applied at the ends of the cantilever beams in such a way that the two identical connections experienced the same moment and shear force. The non-linear moment-rotation characteristics for the connections were determined and the modes of failure established. Another four tests were conducted on different 8 inch beam-to-column connections which can be categorised as being semi-rigid. Two of these connections used steel cleats for the top and bottom seat cleats while the other two had these pieces manufactured of pre-preg glass FRP using a pressure moulding process. The details and the results of these connection tests are presented. The results of the three tests on pinned connections confirmed conclusions previously reported on similar tests where the beams and column were of the 8 inch wide flange profile. The current practice of recommending that the cleated webs have combined bonding and bolting is shown to provide little additional benefit over that when the connection is bolted. It is found that a semi-rigid connection with an acceptable moment-rotation behaviour can be obtained using steel angles for the connection pieces. One of the two 'all' FRP connections was also found to have an acceptable moment-rotation characteristic but would be too complicated for real applications. The search therefore continues for the all FRP connection details giving suitable connection behaviour. Combining the results from these experiments and the analysis of the failure modes, a number of futuristic connection designs are proposed. They include a thin shell cleat piece with curvature to increase its stiffness, six connection details using pieces that connect together by interlock and bonding (this approach reduces the need for bolting) and a radically novel system which does not mimic current steelwork practice. A new analytical method is presented which predicts the static response of nonlinear elastic plane frames of polymeric composite members. Options allow for horizontal and vertical loading, second-order deflections and connections with nonlinear moment-rotation characteristics. The matrix stiffness method uses a new approach to cope with the real connection behaviour. The other novel aspects of the analysis are shear deformable members and new stability functions which account for the shear deformation when determining second-order deflections. A number of new (< p) functions are derived to group the new stability functions, and these can readily be employed in the computing analysis. The analysis is successfully benchmarked against known semi-rigid frame problems of steelwork and with the limited results from a single experiment on a pultruded single bay frame. A serviceability beam line is presented for beam design and a moment equalized connection stiffness is obtained. Two unbraced and one braced frame problems are analysed in a parametric study to determine the effect on frame response of having connections with various properties. Live loading is vertical with a horizontal component. Results of overall sway deflection showed how the frames respond when the connection properties are changed from pinned, through semi-rigid, to fully fixed. The sensitivity of the connection stiffness on the overall frame behaviour is demonstrated by the sway and the midspan deflections results, and by the moment distribution in the members. The analysis is shown to provide useful information in our quest for the optimised connection design and their performance when viewed as an integral part of a whole frame. To establish which connection details are best suited to pultruded frame construction recommendations for further research and development work are given.

Thermal spray tooling is one of a number of technologies which have been developed to satisfy the need for low cost tooling, which is used when prototype components are required in the correct engineering material. In its current state, the technology has a number of fundamental shortcomings. The aim of this portfolio was to address these shortcomings, via a combination of experimental work and technology demonstrators - these are summarised as follows: • An experimental programme aimed to quantify many of the problems associated with thermal spray tooling. A wide variety of tests on thermal spray surfaces was carried out, in order to compare their performance with other 'low cost' tooling techniques. For the first time, tooling shells were produced using the High Velocity Oxy-Fuel (HVOF) technique. This system is capable of producing extremely high quality tool shells, and the technique developed involves the novel use of castable ceramic patterns - the first time a releasable pattern has been developed for this spray system. In addition, it was established that 'hybrid' tooling shells could be produced - these were formed using a combination of arc spray and HVOF layers. The work proved that these hybrid shells could provide substantial performance benefits in terms of wear performance and vacuum integrity, when compared to conventional arc sprayed shells - this benefit was also achieved without significant cost penalty. The programme also investigated the effect of thermal cycling on thermal spray samples - it was shown that repeated cycling at high temperature had an adverse effect on both arc sprayed and HVOF samples - the extent of this effect was very much dependent on the material. • The portfolio includes a technology demonstrator programme, which was carried out for Rover Group to show the potential of thermal spray tooling. The programme entailed the manufacture of a suite of 5 tools for compression moulding of Glass Mat Thermoplastic(GMT). The actual route used for the production of the tooling suite involved many unique features, which had not previously been utilised for thermal spray tooling production. One of the tools is the largest ever produced for compression moulding using thermal spraying, being approximately 4m2, and weighing in excess of 3 tonnes. Due to the compressive stresses involved in the moulding process, conventional resin backing systems were unsuitable for this tooling. It was therefore necessary to use a Chemically Bonded Ceramic (CBC) material, with an exceptionally high compressive strength. However, this material does not adhere to thermal spray surfaces, and it was therefore important to develop a novel fixing method at the interface of the materials. Further to this, in certain cases the use of thermal spraying was precluded by the component geometry - in these cases it was necessary to use the CBC material as the direct tool face. This was the first time that CBC tooling had been used for compression moulding GMT, and it was therefore necessary to develop new post-treatments for this inherently porous material. The moulding operation then entailed the development of specific techniques and conditions for this prototype tooling, which would not generally be used in production - normal moulding conditions for 'production' tooling were therefore inappropriate. Further work will entail materials development, the introduction of automation and development of design rules, specifically aimed at the production of large tooling for the aerospace and automotive sectors - this will be carried out via a successful project submission under the Innovative Manufacturing Initiative (IMI).

Communication between the parties in a project of an integrated collaborative engineering system has been the subject of active research for many years. The construction industry has a long tradition of collaborative working between the members of the construction team. At the design stage, this has traditionally been based on physical meetings between representatives of the principal design team members. To aid these meetings, the information and communication technologies that are currently available have been used. These Information Technology (IT) tools have produced some success but are held back by the problems posed by the use of diverse software tools and the lack of effective collaboration tools. The collaboration tools are necessary to reduce the time and distance constraints, in the increasingly global design teamwork. IT-supported collaborative construction design refers to actors in product design processing, working together on the same project with IT networks used for mediation to overcome time and geographical constraints. Fragmentation of the project management of a building construction between different specialists may be necessary, but good communication and coordination among the participants is essential to accomplish the overall goals of the project. New information technologies can be helpful in this process, especially the Internet and specialised extranets. A collaborative Architecture, Engineering and Construction (AEC) design environment has been proposed by this research to integrate the work of distributed project participants. Based on identified functional requirements, the conventional building product models have been extended to incorporate high-level concepts such as activity and organisation, which are essential for coordination and collaboration. A generic human-project-human interaction model has been developed, which could not only make the building domain models interaction-aware, but also serve as a base model for developing general interaction utilities. A collaborative design environment prototype has been described, covering the common project workspace, general interaction utilities and multi-user interfaces. This study characterises collaboration as a function of time, space and shared working environment with enabled real-time design tools over the World Wide Web (WWW). To realise the proposal of this research the inter-mediated design communication, visual presentation, integration and organisation frameworks, groupware technology, and interactive multimedia tools are used. This study presents the CODE (COllaborative Design Environment) system. This Architecture, Engineering and Construction (AEC) virtual working space is argued to support collaboration and teamwork in real time. The evaluation of the system showed its feasibility and reliability through a workshop. The results showed that the CODE system can assist the collaborative AEC design process.

This thesis documents a programme of work undertaken from mid-2005 to mid-2009 as a part-time PhD, investigating the application of signal-processing methods to ultrasonic non-destructive evaluation (NDE) data from fibre-reinforced composite materials. The aims of the project were: •to push the boundaries of defect detectability by applying knowledge-based filtering methods to remove the response of the structure; •to produce 3D profile maps of various measured parameters to assist in differentiating between defects and structural effects; •to present the NDE information in terms of actual material properties that can be easily interpreted. These aims are linked to specific NDE problems in inhomogeneous materials: •3D characterisation of the material properties and defects in composite materials such as carbon-fibre reinforced plastic (CFRP); •3D mapping of ply wrinkling and fibre orientation in CFRP and glass-fibre reinforced plastic (GFRP). By developing and using a model, it was possible to understand the ultrasonic response of multi-layered structures when the layers themselves comprise both fibres and matrix. Various defects were inserted into the model to determine which parameters from the ultrasonic response would provide good distinction between defect types and enable quantitative 3D profiling of the required material properties. A toolset of signal-processing and image-processing algorithms was used to apply the methods to both simulated and real ultrasonic data from the above NDE problems in order to demonstrate the benefits of the new methods. At various stages through the project a validation process was undertaken to evaluate the methods for use on real composite aerostructures.