Electrochemical Jet Processing (EJP) techniques have been traditionally limited in application by the inherent geometric inflexibility and limited process precision in comparison to alternative processes. It has been stated that process resultant geometries are defined by the Gaussian in-jet energy distribution and the hydrodynamic stagnation region formed under a jet on an impinging surface. This thesis reports upon investigations and innovations designed to challenge these assumptions. EJP is an emergent manufacturing process with a unique capability of subtraction and deposition of metals within a common machine tool. EJP demonstrates advantages beyond traditional electrochemical machining and electrochemical deposition including a high degree of flexibility, simplistic and therefore low-cost plant, requiring no complex, high-cost tooling and no masking requirement to achieve high fidelity geometries. These process traits are attractive to industry but EJP has yet to find significant commercial use. Electromechanical and electrochemical innovations are presented here demonstrated by electrochemical jet machining (EJM) the subtractive mode of EJP, which allow modulation of the properties of the inter-electrode gap leading to a paradigm shift in the functionality, precision and application of EJP. Electromechanical innovations demonstrate that the Gaussian energy distribution can be modified through the articulation of the jet angle of address and modified jet nozzles to manipulate the in-jet resistance. The outcome being the capability to produce bespoke removal profiles with increased precision and flexibility of form alongside refined surface finishes. Electrochemical innovations demonstrate an increase in precision through reducing overcut and reducing the feature shoulder radius when using a modified electrolyte. When these electromechanical and electrochemical innovations are coupled together, the overcut traditionally seen to be twice the nozzle diameter is reduced by 99%. Therefore, features can be created at kerfs approaching the nozzle diameter. Alongside this, a bespoke research platform has been built and developed to exploit these findings and incorporate features such as the rotational head for constant profiling and multiplexing of electrolytes to enhance the flexibility of the process. Process enhancements developed through this thesis have allowed the manipulation of the in-jet energy density profile and dissociation of the dissolution region from hydrodynamic phenomena thus allowing surface structuring by EJP to be developed well beyond the state-of-the-art.

Electrochemical jet processing (EJP) is an applied electrochemical technique capable of exercising highly localised control of material removal independent of mechanical properties. This makes the process suitable for both micromachining and surface texturing operations in high-value engineering materials, without altering the near-surface in a thermomechanical manner. The research presented in this thesis primarily investigated the generation and characterisation of topographies arising from EJP, since topography can strongly affect functional and mechanical properties of the material. It was found that the resulting surface texture was directly influenced by the starting material microstructure, even in processing regimes beyond which the microstructure was thought to make a difference. This was proposed to be the result of the high flow velocities in EJP. In addition, under appropriate processing regimes, the microscale topography is sensitive to underlying microstructural characteristics such as orientation, localised composition, defect density and thermal history. This was applied to develop a large-area microstructural characterisation technique, which when calibrated against a conventional approach, is capable of identifying localised crystallographic texture. This was applied to common engineering materials such as nickel, aluminium alloys and copper. The second objective of the thesis was to innovate the geometry of processed features. Conventionally, material removal is shown to be a transformation of the Gaussian energy distribution within the electrolyte jet. Through small additions of doping agents, the low energy area, responsible for tapering of the machined feature, can be reduced. This leads to an increase in precision and dimensional accuracy. In addition, it is shown that individual corrosion pits can be propagated, which represents the development of a novel form of electrochemical processing, capable of further reducing the scale of this micromachining process, as well as easily generating fractal surface patterning. In addition, the thesis explores the viability of EJP as a coating technology. This was firstly observed through electroplating operations, where a high level of control over the deposit morphology was demonstrated through electrolyte design. Subsequently a methodology was presented regarding the co-deposition of particulate matter within a metallic deposit. Finally, EJP was presented as a route through which more robust surfaces with interesting functional properties could be generated as part of an in-jet plasma electrolytic oxidation process.

Early fault detection and diagnosis of diesel engines are paramount now, especially with countries like the UK and France, in-line with the 2015 Paris agreement on climate change, making plans to ban the use of an automobile with diesel and petrol engines before the year 2040. This ban could affect other sectors where diesel engines are the prime mover and result in more stringent exhaust emission regulations. The instantaneous angular speed (IAS) model based fault diagnosis has shown more prospects of fault detection and location. However, there are serious gaps in available knowledge regarding IAS model based fault diagnosis which takes into account the effect of the system’s modal properties. Hence, this research focuses on the online modal properties identification of a typical engine-load system for an improved performance of IAS based fault diagnosis. Having acknowledged the essentials of IAS based fault diagnosis techniques through a comprehensive literature study, this research firstly investigates the impact of modal properties on the IAS of a four-cylinder engine. This is achieved through a three degree of freedom (DOF) torsional vibration model of the engine-load system, which allows for the modal properties of the system to be calculated and analysed. The calculated modal properties of the system showed one rigid and two flexible modes which had a low (< 13Hz) and high (< 92Hz) frequencies. The mode shape of the low frequency resonance shows more amplitude on the flywheel-load reference point of the system while that of the high frequency resonance shows more amplitude on the engine-flywheel reference point of the system. It then simulated the IAS which represents the torsional vibration signature with altered modal properties. The simulated result demonstrated that the low frequency resonance is more sensitive to the peak and trough values of the IAS waveform. After identifying the deployment merits of operational modal analysis (OMA) techniques through a comprehensive literature study, this research then explore the prospect of an IAS based output-only modal properties identification of a typical engine-load system. This was done through both experimental and simulation evaluations, which allowed simulated and experimental IAS to be used for implementing covariance-driven reference based stochastic subspace identification (SSI). The simulated result using pseudo-random input shows that the identified resonance frequencies and mode shapes are 80% correlated with the calculated ones. The simulation results also demonstrated that the accuracy of the identified modal properties is dependent on the number of IAS responses used for implementing the covariance-driven reference based SSI technique. The experimental result using estimated IAS during engine shutdown operation showed that both high and low frequency vibration mode can be identified. The identified resonance frequencies with their mode shapes are 80% correlated with the predicted ones. Having identified the modal properties of the engine-load system online through the implementation of an IAS based covariance-driven SSI, this research then investigates the impact of misfire on the system’s modal properties especially the mode shape of the low frequency resonance. This was achieved experimentally by inducing a complete misfire in respective cylinders (1st, 3rd and 4th) and the IAS estimated during engine’s transient shutdown operation was used for implementing a covariance-driven reference based stochastic subspace modal properties identification. While the mode shape of the identified high frequency resonance (< 80Hz) showed no characteristics for cylinder misfire detection, that of the low frequency resonance (< 13Hz) did. Faults in the engine’s injection system and an abnormal clearance valve train conditions significantly affects its combustion process. The cylinder by cylinder pressure torque obtained from measured IAS through order domain deconvolution technique can be used to detect and diagnose injection faults. In the interim, this research has also recognised that the closer the low-resonance frequency of the model used for the order domain deconvolution gets to its real time value the more accurate the pressure torque becomes. The reconstructed pressure torque which takes into consideration the real time low frequency resonance can be used to detect faulty injection system with different severities and abnormal clearance valve conditions of several severities. Furthermore, the importance of an accurate modal properties utilisation in IAS model.

Local measurements of the dispersed phase properties in air-water bubbly flows are of primary importance to understand the hydrodynamic characteristics of multiphase flows. One of the essential requirements in designing multiphase flow systems is to determine its flow regime since many constitutive models are flow regime dependent. In bubbly multiphase flow, the bubble diameter plays a vital role in hydrodynamics of flow. In this study, a novel invasive measuring instrumentation system has been designed and developed to determine the bubble size and shape accurately by minimising the effects of the bubble-sensor interactions. This instrumentation system has been used to determine the effects of the bubble size on the volume fraction distribution and the hydrodynamic behaviour of air-water two-phase flow. The novelty of this probe arises from the fact that the data is collected from the first bubble-sensor contact, unlike the previous methods in which the data has been collected from two points namely, first when the sensors’ tips immersed a bubble and second when the sensors’ tips left the bubble. The seven-sensor conductivity probe subsequently has been used to determine the dispersed phase local parameters. These parameters include bubble velocity, time-averaged local void fraction and bubble shape and size. The data from this probe has been acquired using National Instruments Data Acquisition (DAQ) and LabVIEW software. The experiments have comprised of two methods, namely bubble column and flow loop. For the bubble column experiments, a new image processing code has been developed for capturing the dispersed phase properties, including the void fraction from the images that have been captured by the high-speed cameras. From the comparison between both methods, the seven-sensor probe and the high-speed camera measurements, good agreement has been achieved. In the flow loop experiments, the novel seven-sensor probe system has been used for measuring the dispersed phase properties from the first bubble sensor contact; moreover, the effect of variation of gas superficial velocity, with the values of 0.05, 0.07 and 0.1 m/s, on the dispersed phase properties have been also investigated.

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Annular extrusion dies have been widely used for the production of plastic pipes and tubes. But they are usually designed according to engineering experience which has led to the overweight and waste in material of them. With increasingly stringent environmental regulations in many countries, attaining lightweight design of mechanical parts and components becomes an ever-lasting goal of designers during design process. Thus a systematic lightweight design methodology which integrates the tools of numerical simulation, structural optimization and life cycle assessment is proposed for annular extrusion dies in the thesis. The implementation of the lightweight design depends on the numerical simulation to model the coupled fluid-thermal-structural process of a typical extrusion operation. The simulation begins with the prediction of the rheological behaviours of polymer melts flowing through an annular extrusion die. The essential flow characteristics including velocity, pressure drop, wall shear stress and temperature are investigated. The Smart Bucket Surface mapping algorithm is then applied to transfer the temperature and pressure loads on flow channel for the following thermal and structural analysis of the extrusion die. The finite element analysis software ANSYS workbench 15.0 is used to calculate the temperature, deformation and thermal stress distribution of the die body. The effects of structure parameters and processing parameters on both the flow pattern of polymer melts and the mechanical properties of the die body are further investigated. Besides, a deformation and high temperature stress measurement system for the extrusion die is constructed using the corresponding sensors and data logger. The measurement results are compared with the simulation results which indicates the effectiveness of the proposed numerical model. Lightweight design of the extrusion die is then conducted using structural optimization. The design parameters and their threshold values which indicate the required performances of productivity, static stiffness, static strength, and manufacturability are identified according to the above numerical simulation results. The Adaptive Response Surface Method (ARSM) is used to solve the optimization scheme to achieve the targeted design parameters with minimum mass. The so-called lightweight coefficient is employed to characterize and evaluate the lightweight designed extrusion die. An extrusion die design example is solved by applying the design criterion of reducing the thickness of die wall. The results show that the structural lightweight design can significantly reduce the weight and increase the lightweight coefficient of extrusion die. To evaluate the effect of lightweight design on the environmental performances of the extrusion die, the life cycle assessment (LCA) is conducted. The stages of life cycle are composed of material stage, manufacture stage, use stage and end of life (EOL) stage. The environmental impacts (EIs) of the extrusion die are modelled as a function of geometrical and processing parameters. The EIs between the original and lightweight designed extrusion die are compared which shows that the proposed lightweight design method has a contribution to both material reduction and EIs of the extrusion die in the entire life cycle. It is foreseeable that the work in the thesis provides a foundation for dealing with lightweight design of conventional heavy duty machine components with complex functionalities.

Solar energy assisted heat pump (SAHP) and Direct Expansion Solar Assisted Heat Pump (DX-SAHP) systems are among the promising means of reducing the consumption of fossil fuels for heat production in residential building applications. The research in this thesis introduces a novel system that integrates solar energy, THS storage, and DX-SAHP. The objective is to develop an efficient heating system for existing homes in the cold climatic region which is sustainable and acts as an alternative to the conventional high energy loss domestic water and space heating systems. One of the prospective techniques of producing and storing of thermal energy is the application of thermochemical materials. Storage of heat in salt hydrates provides an efficient and compact way of storing energy. Hence, the properties of salt hydrates that determine the storage capacity are being investigated. An experimental test has undertaken to assess the effect of integrating the new design of thermochemical storage materials with a solar-assisted multifunctional heat pump system. This research presents a novel design that involves the integration of DX-SAMHP and a hot water tank with a thermochemical sorption jacket. Investigations have been carried out to determine a suitable temperature range for household heating systems. Expanded Vermiculite (host matrix) and CaCl2 (hygroscopic salt) have been used as composite material in an adsorbent reaction jacket for a domestic water tank. The new design has a total volume of 20 kg of V/CaCl2, which can store the thermal energy with a complete reaction. The results show the high capability of the tested materials to enhance the domestic heating system performance when applied in cold regions. The feasibility of the designed system for residential space and water heating is also demonstrated. The maximum energy density obtained through the discharging process is 565 kJ/kg. It is also revealed that the coupling of thermochemical heat storage and heat pump increases the thermal production capacity by 1.166 kWh during the discharging process.

In this work, parametric FE (Finite Element) modelling has been developed and used to study the deformation of soft materials with different embedded systems under indentation and more complex conditions. The deformation of a soft material with an embedded stiffer layer under cylindrical flat indenter was investigated through FE modelling. A practical approach in modelling embedded system is evaluated and presented. The FE results are correlated with an analytical solution for homogenous materials and results from a mathematical approach for embedded systems in a half space. The influence of auxeticity on the indentation stiffness ratio and the de-formation of the embedded system under different conditions (indenter size, thickness and embedment depth of the embedded layer) was established and key mechanisms of the Poisson’s ratio effect are highlighted. The results show that the auxeticity of the matrix has a direct influence on the indentation stiffness of the system with an embedded layer. The enhancement of indentation resistance due to embedment increases, as the matrix Poisson’s ratio is decreased to zero and to negative values. The indentation stiffness could be increased by over 30% with a thin inextensible shell on top of a negative Poisson’s ratio matrix. The deformation of the embedded layer is found to be significantly influenced by the auxeticity of the matrix. Selected case studies show that the modelling approach developed is effective in simulating piezoelectrical sensors, and force sensitive resistor, as well as investigating the deformation and embedded auxetic meshes. A full scale parametric FE foot model is developed to simulate the deformation of the human foot under different conditions including soles with embedded shells and negative Poisson’s ratio. The models used a full bone structure and effective embedded structure method to increase the modelling efficiency. A hexahedral dominated meshing scheme was applied on the surface of the foot bones and skin. An explicit solver (Abaqus/Explicit) was used to simulate the transient landing process. Navicular drop tests have been performed and the displacement of the Navicular bone is measured using a 3D image analysing system. The experimental results show a good agreement with the numerical models and published data. The detailed deformation of the Navicular bone and factors affecting the Navicular bone displacement and measurement is discussed. The stress level and rate of stress increase in the Metatarsals and the injury risk in the foot between forefoot strike (FS) and rearfoot (RS) is evaluated and discussed. A detailed full parametric FE foot model is developed and validated. The deformation and internal energy of the foot and stresses in the metatarsals are comparatively investigated. The results for forefoot strike tests showed an overall higher average stress level in the metatarsals during the entire landing cycle than that for rearfoot strike. The increased rate of the metatarsal stress from the 0.5 body weight (BW) to 2 BW load point is 30.76% for forefoot strike and 21.39% for rearfoot strike. The maximum rate of stress increase among the five metatarsals is observed on the 1st metatarsal in both landing modes. The results indicate that high stress level during forefoot landing phase may increase potential of metatarsal injuries. The FE was used to evaluate the effect of embedded shell and auxetic materials on the foot-shoe sole interaction influencing both the contact area and the pressure. The work suggests that application of the auxetic matrix with embedded shell can reinforce the indentation resistance without changing the elastic modulus of the material which can optimise the wearing experience as well as providing enough support for wearers. . Potential approaches of using auxetic structures and randomly distributed 2D inclusion embedded in a soft matrix for footwear application is discussed. The design and modelling of foot prosthetic, which resembles the human foot structure with a rigid structure embedded in soft matrix is also presented and discussed.

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The BDyn device is a bilateral posterior dynamic stabilisation spinal implant used to treat degenerative disc disease. The BDyn device consists of a polycarbonate urethane (PCU) component, a silicone component, a mobile titanium alloy rod, a fixed titanium alloy rod and it is fixed to the vertebrae by titanium alloy pedicle screws. The viscoelastic properties, chemical structure and surface morphological changes of the untreated, in vitro degraded and in vivo degraded were compared. The macro and micro-scale viscoelastic properties, chemical structure and surface morphology of five long-term implantable PCU biomaterials, which were in vitro degraded by four separate degradation methods were also investigated. No resonant frequencies were reported for the untreated and in vitro degraded components and devices however, resonance was detected in the frequency sweep test of BDyn Explant 2 with the sharp increase of the loss stiffness occurred at 4 Hz; this highlights the importance of evaluating orthopaedic devices with frequency dependent mechanical testing techniques. The biomaterials were viscoelastic throughout the frequency range tested and were significantly different at specific frequencies when comparing untreated specimens to specimens degraded by a specific degradation method; this further highlights the need to evaluate elastomeric biomaterials with frequency dependent mechanical testing techniques.