Truck manufacturers are currently under pressure to reduce pollution and cost of transportation. The cost efficient way to reduce CO[sub]2 and cost is to reduce fuel consumption by adaptation of the vehicle speed to the driving conditions - by heuristic knowledge or mathematical optimisation. Due to their experience, professional drivers are capable of driving with great efficiency in terms of fuel consumption. The key research question addressed in this work is the comparison of the fuel efficiency for an unassisted drive by an experienced professional driver versus an enhanced drive using driver assistance system. The motivation for this is based on the advantage of such a system in terms of price (lower than driver's training) but potentially it can be challenging to obtain drivers' acceptance of the system. There is a range of fundamental issued that have to be addressed prior to the design and implementation of the driver assistance system. The first issue is related to the evaluation of the correctness of the prediction model under development, due to a range of inaccuracies introduced by slope errors in digital maps, imprecise modelling of combustion engine, vehicle physics etc. The second issue is related to the challenge in selecting a suitable method for optimisation of mixed integer non-linear systems. Dynamic Programming proved to be very suitable for this work and some methods of search space reduction are presented here. Also an analytical solution of the Bernoulli differential equation of the vehicle dynamics is presented and used here in order to reduce computing effort. Extensive simulation and driving tests were performed using different driving approaches to compare well trained human experts with a range of different driving assistance systems based on standard cruise control, heuristic and mathematical optimisation. Finally the acceptance of the systems by drivers been evaluated.

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In this dissertation a study of numerical simulations of turbulent diffusion flames and pool fires is presented. In order to account for the physical coupling of turbulent mixing and combustion, the large eddy simulation (LES) technique is used. The subgrid-scale (SGS) modelling for both turbulence and combustion are examined in details and a modified version of SGS combustion model has been proposed. For SGS turbulence modelling, the dynamic approach is used. This approach allows the model coefficient to be updated temporally and spatially and it can be used to account for the energy back-scattering. For SGS combustion modelling, a conserved scalar approach, namely the laminar flamelet model is used. Due to the tiny scale of combustion, it could be infeasible for modern computers to execute a direct calculation of an industrial combustion application. By treating the fire flame as an assembly of thin flames (flamelets), the laminar flamelet model has managed to separate the chemical reaction from the turbulence mixing. The calculation of laminar flamelet approach is relatively independent of LES. The calculations of turbulence and combustion are interacted by a conserved scalar called mixture fraction. Contribution has been made by the candidate to the application and optimisations of the SGS models. Those optimisations are based on the applications to pool fires and bluff body flows. In SGS combustion modelling, the variance of mixture fraction and the scalar dissipation rate are modelled from the mixture fraction rather than solving the governing equations. This simplification has dramatically cut the computational expense and has virtually turned the 3-D look-up table to a 1-D format. During the calculation of the heat release rate, the contribution of both reactants and products are considered. For pool fires, the constant thermodynamics pressure is used to effectively establish the relation between the temperature and density fields. Pool fires with different burner diameters and various types of fuels have been simulated using LES with the above SGS modelling. All cases are studied under 3-D mode. In addition to the analysis of the distribution of mean flow quantities (temperature, density, velocities, etc), considerable effort has been directed towards the sudy of the time development and the dynamic behaviours. Different characteristics have been identified for medium and small pool fires. The dynamic approach of SGS turbulence modelling has also been applied to the simulation of bluff body flows. The simulations were carried out using the LES package called Fire Dynamics Simulator (FDS), which is developed by the researchers in the National Institute of Standards and Technology (NIST), U.S.A. During the period of the Ph.D study, the FDS codes were updated several times by both the researchers in NIST and the candidate. The update covers the combustion modelling, radiation modelling, meshing and some other aspects. The simulations were carried out on a single processor Pentium IV PC with 2G-RAM. The number of cells in each simulation was generally between 1 and 2 million with the finest grid resolution being in the order of millimetre. The predictions are compared with the experimental measurement and other established simulation data. The ability of capturing the instantaneous flow movement and dealing with the realistic geometries has made LES with appropriate SGS modelling an effective and promising tool for the numerical study of turbulence and combustion. The laminar flamelet approach of SGS combustion modelling has established progressive relationship between the modelling of turbulence and the modelling of combustion. As a recommendation, the extending use of the dynamic approach has been proposed. With more accurate determination of the model coefficient in SGS modelling, LES is expected to cope with even higher Reynolds number flows in more complicated geometries.

The experimental and analytical modal analysis is used to establish a system modelling methodology in rotating structures, which subsequently can help in design and development of rotating machinery. The purpose of the study is to develop and use modal testing and vibration analysis which would involve obtaining the mathematical model of the system from the test data and subsequently obtaining the unbalanced parameters. The research work includes the application of modal testing method in rotor rig to investigate different modal parameters and detect the behaviour and performance of rotating machinery. This method would be capable of solving many of the related rotating machine problems, such as in turbine and compressor. Unbalance is one of the problems which exist in rotating machinery. Balancing is usually an expensive and laborious procedure and a balancing system would be beneficial for rotor dynamic systems and power generation applications. Excess vibration can cause noise, cyclic stress and wear in machinery. It is important to identify all the critical speeds within the range of operation and analyse the damping effect, mass unbalance and other phenomena in rotating machinery and their effects in their safe operation. These will be investigated in this study. There are several phenomena associated with rotating machinery such as centrifugal and gyroscopic forces which would create complexity in the mathematical procedures in modal analysis that they need to be addressed and interpreted appropriately before they could be used in modal testing of rotating machinery. The experimental technique used in this thesis to obtain the modal and dynamic response properties of structures. This technique has been applied to rotating structures, however the full implementation of modal testing in rotating structures and the implications are not fully understood. and are therefore in need of further investigations. In this study the Frequency Response Function (FRF) data obtained from the specific experimental results are curve-fitted by theoretical data regenerated from overall statistical analysis of measured data. Different excitation methods are used in experiment (hammer and shaker). For hammer test, transient signal is produced. While for shaker test, different vibration signals are produced (Sine, Random and Burst Random). In shaker test, a special frame was designed and used around a plain bearing and the accelerometers were attached to the outer surface of the bearing to measure the response of the lateral motion on several points of the shaft. The excitation force with help of push' rod was generated and applied to the shaft. This method can help to solve the problem in the attachment of shaker and force transducers to the rotor system. The analysis of vibration suppression with different locations and configurations of the unbalanced masses and effect of the adding of balance masses to suppress the vibration amplitude has been studied properly. The experimental results were used for verification of Finite Element (FE) models, since it has good capability for eigen analysis and also good graphical facility. 3-D models result in large number of nodes and elements. This project demonstrates how to extract a plane 2-D model from the 3-D model that can be used with fewer nodes and elements with no loss in accuracy of the results. Transient orbit analysis in the literature indicates that the bearing stiffness and damping affects the vibration amplitude. In this project the study of the effects on the bearing reaction forces and cyclic. bending stress will be investigated. It is envisaged that the approach is not limited to the condition diagnosis and predictive failure but could help the designers to have better understanding of rotor performance at the system design stage. The experimental data are used to characterise the dynamic behaviour of the system and introduce to the correction unbalance to suppress the excess vibration. The experimental data are also used to generate the FE models and subsequently calculate the dynamic reaction forces in the bearings and the cyclic bending stress.

In this study, a new method to fabricate high performance intermetallic and ceramic materials and coatings was developed using the SHS process. Induction heating was used as an ignition source to initiate the SHS reaction of Ni/Al and preheat the steel substrate, while titanium was used as an underlayer to facilitate the adhesion between the coatings and the substrate. The reactions were performed in a reaction chamber with an atmosphere of argon gas, while the combustion temperatures were measured using type-K thermocouple and infrared pyrometer. The microstructure characterizations of synthesized products were conducted using SEM, XRD and laser Raman microspectroscopy. Vickers indentation tester was used to evaluate the microhardness and the adhesion strength of the coatings. In the fabrication of NiAl coating, the formation of NiAl was initiated by the melting of Al and subsequently reacted with Ni to form NiAl after receiving the heat generated by induction heating. The synthesized product formed a liquid phase during the reaction and partly diffused into the Ti underlayer. The heat released by Ni/Al reaction then promoted the melting of Ti and further reactions between Ti and Ni/Al to produce Ti3Al–Ti2Ni composites, whereas the unreacted Ti formed an alloy with the coating material. The heat released by Ni/Al reaction and that generated by induction heating were also responsible for the formation of metallurgical bonding in the interface between the underlayer and the substrate. The effects of current variations, underlayer thickness, compaction pressure and melting point of underlayer on the microstructure of synthesized products were investigated. The mechanical properties and thermal shock resistance of synthesized products were also studied. To investigate the effect of reactant compositions on the combustion temperature, microstructure and mechanical properties of synthesized products, NiAl–TiC–Al2O3 composites were fabricated using a low cost TiO2. The microstructure of synthesized product showed that the reaction of Ni/Al and TiO2/Al/C was complete. Two reaction stages were observed from the temperature profiles which represent the exothermic reaction of TiO2/Al/C system and the phase transformation of Ni/Al system. An increase in the TiO2/Al/C content increased the combustion temperature. However, the maximum temperature was still lower than the melting point of TiC and Al2O3 indicating that both products were formed in the solid state during the reaction. An increase in the TiO2/Al/C content produced a higher porosity in the product due to the increase of the solid TiC and Al2O3 particles compared with that of the liquid NiAl. The Ni/Al reactions acted as an exothermic agent to the ignition of TiO2/Al/C reaction, and increased the liquid content for improving the density of synthesized product. The microhardness of synthesized product also increased with an increase in the TiO2/Al/C content due to the increased content of the ceramic particles. In the fabrication of TiC intermetallic composite coating, induction heating was successfully used to initiate the exothermic reaction of the reactants composed of multilayer configurations of Ti/C, Ni/Al and Ti. The synthesized product was inhomogeneously composed of TiC/Ti3Al/Ti2Ni, while a small amount of TiO2 oxides and unreacted C were also observed. The hardness of TiC/Ti3Al/Ti2Ni was 1135.48 ± 139.58 HV, indicating that a hard TiC intermetallic composite coating was successfully synthesized using induction heating.

Sprinklers are automatically activated fixed installation suppression devices. They have found extensive applications due to minimum protection they provide for a wide range of applications including residential and warehouses. Modelling sprinkler atomization is a challenging task, due to the stochastic nature in impingement of water jets and the added complexity of sprinkler configuration. In the literature, a spray initiation framework has been developed to address the multidimensional stochastic complexity associated with fire sprinklers. The initial sprinkler spray is completely characterized in terms of the following main parameters: droplet spatial location (radius, elevation angle and azimuthal angle), droplet velocity, droplet diameter and the spatial volume flux. The present thesis aims to improve the prediction of the initial sprinkler spray characteristics through exploring different physics based modelling approaches. The sub-models for film flow and sheet trajectory adopted in the development of the fire sprinkler spray models are reviewed. Three new deterministic approaches for sprinkler atomization have been proposed by employing an existing film submodel and a detailed water sheet trajectory sub-model which has never been used for fire sprinkler applications. The developed methods simulate the orthogonal impingement of water jet to a deflecting disk, with the potential to be adapted for tilted deflectors. A comparative analysis is carried out between the three introduced methods and a reference model in terms of their predictions for droplet median diameter and initial droplet location for a range of ambient temperatures and water injection pressures. The developed methodologies have been further expanded by incorporating random behaviour to the spray formation procedure. The stochastically predicted mean velocity and volume median diameter have been compared against robust experimental data and empirical correlations. The improvements obtained by the developed methodologies are promising. In further steps, a dimensionless formulation for predicting spray characteristics, sheet breakup distance and droplet sizes, in impinging atomizers have been developed. The developed formulation is validated for impingements led the spray to occur in the rim breakup mode. Building on the proposed methodologies, a semi empirical model has been developed capable of predicting the near field spray characteristics such as spatial distribution of droplet sizes, velocities and spray volume flux from local volume fraction measurements. The research outcome would benefit the computation fluid dynamic packages to initialize the spray in a more realistic manner. The study undertaken would lead to more efficient fire suppression and/or water and fire interaction studies. In addition to this, the methodology could reduce the cost of experiments in order to quantify new sprinkler sprays.

Lidars are very promising instruments for the remote-sensing of the Earth, and are eagerly awaited for operational missions, particularly in the observation of the atmosphere. However, spaceborne lidars are still in their early development and there have been many setbacks associated with their technology. The high energy of the laser beam contributes to the formation of contamination deposit on laser optics, leading to the degradation of the lidar performance and eventual failure of the instrument. This high energy requirement can partially or totally be offset by a larger telescope and / or a lower orbit, with the implication of a greater drag force acting on the satellite. This work investigates the options for satellite and lidar telescope configuration which minimise their contribution to drag while maximising the telescope aperture diameter for lidar performance. A MATLAB/Simulink trajectory model is developed to establish the propulsion requirements for drag compensation. Parametric models are used to size the satellite, its subsystem and the lidar. This study elaborates the conditions under which a lidar mission might work in a low altitude orbit. In particular, it explores the feasibility and applicability of four concepts against the requirements of some challenging lidar missions. The model developed also identifies that past studies may have under-estimated the electric propulsion requirements for lidar missions in low altitudes.

Ice accretion on the wing and nacelle leading edges diminishes aerodynamic performance and increases fuel consumption and chances of aircraft crash. For these reasons, the Federal Aviation Administration mandates aircraft manufacturers to demonstrate that their aircraft can fly safely in icing conditions. This study has investigated the thermal performance and measures for improvement of Swirl Anti‐Icing (SAI) systems in preventing ice accretion on nacelle leading edges. A Piccolo Tube Anti‐Icing (PTAI) system with experimental data was used as the benchmark of this study. PTAI consists of perforated pipe and is installed inside the wing and/or nacelle leading edge. The hot air from the compressor is directed onto inner skin through the holes/nozzles in a perforated pipe. As a result, the inner skin is warmed up and free from icing. In this study, numerical simulations have been performed to analyse the thermal performance of PTAI at 4 different altitudes/scenarios namely Ground Run, Climb, Hold and Descent. The FLUENT CFD results demonstrated excellent agreements with the experimental data obtained by Bombardier Aerospace. Based on the results, the gradient coefficients of the empirical equations proposed by colleagues have been modified to take into account the ambient air temperature in order to make the correlations suitable for all the 4 conditions analysed. In future, Bias flow Acoustic Liner (BAL) is expected to be employed in engine nacelle and to form part of the inner skin of nacelle lip. The hotspots produced by PTAI would possibly destroy BAL. Thus, an old and mature technology, SAI, was further investigated in the present study with a hope to get rid of hotspot phenomenon on the inner skin and to increase the efficiency of the system. SAI has better temperature distribution along nacelle lip‐skin than that of PTAI. In addition, SAI contains fewer components, requires simple plumbing, and is light and inexpensive both for the system itself and for maintenance of the system compared to PTAI. Some potential modifications of nozzle including sloped nozzle, altered nozzle length and nozzle outlet, rotated nozzle towards inner skin, decreased exhaust area and increased nozzle diameter have been proposed and investigated in order to improve thermal performance of SAI. According to the results, only nozzle directions and nozzle diameters had significant effects on the thermal performance of SAI although all the modifications would have certain effects on anti icing performances of SAI. Thermal performance of SAI was inversely related to nozzle diameter. The hotspot temperature decreased by 18.53°C and cold spot temperature increased by 2.30°C respectively as the nozzle rotated 13° towards inner skin at hot air mass flow rate of 0.0118kg/s. For hot air mass flow rate of 0.04536 kg/s, the cold spot temperature decreased from 28.78 to 6.37°C as nozzle diameter increased from 0.0127m to 0.0254m. In addition, the temperature distribution on the nacelle lip‐skin has improved as the angle of nozzle direction towards inner skin increased. Based on the results, novel empirical correlations for SAI system have been developed and presented. The augmentor was employed in SAI system in order to enhance momentum and heat exchanges between hot air and cold air in the D‐chamber. As a result, the uniformity of temperature distribution and thermal performance of SAI on the nacelle lip‐skin were improved. The results showed that the thermal performance of SAI with augmentor increased with the increase of hot air mass flow rate. Although SAI with Augmentor 3 at 2° rotation showed poor thermal performance than SAI without augmentor but nozzle rotating at 13° with hot air mass flow rate above 0.028kg/s, the former showed better thermal performance than latter for hot air mass flow rate equal to or lower than 0.028kg/s. The performance of the Final nozzle was also tested and compared with the performances of Circle nozzle and ellipse nozzle 1. The final design of the nozzle has demonstrated the best performance at any given hot air mass flow rate, especially at 0.04356 kg/s. At this mass flow rate, Ctem deviation, hotspot temperature and cold spot temperature were 13.19%, 371.42K and 322.02K respectively. The hotspot temperature, temperature difference between hotspot and cold spot, standard temperature deviation and coefficient of temperature deviation produced by SAI were lower, while anti‐icing efficiency and cold‐spot temperature of SAI were higher than PTAI despite PTAI having higher average inner skin temperature than SAI. In other words, SAI showed better uniform temperature distribution on the nacelle lip‐skin compared to PTAI.

Two configurations that have received a great deal of attention in the last decades are namely the single-fin and double-fin. In these interactions, deflected un-swept sharp fins are used to generate single-swept and double-crossing oblique shock-waves that interact with a supersonic/hypersonic turbulent boundary-layer developing over a flat plate. Following the swept-shock interaction, the study of crossing-shock interaction represents a logical progression in the general study of shock- wave / turbulent boundary-layer interactions (SWTBLIS). These rather simple geometries allow isolating the inherent flow physics which can be applied to more complex configurations. Besides having fundamental importance, swept- and crossing-shock interactions also have important engineering applications. Research findings on single-fin can be applied, for example, in the design of wing/tail fuselage juncture, and in high incidence flows on swept delta wings and slender bodies. The double-fin, on the other hand, could represent a simplification of a high-speed inlet of vehicles employing air-breathing propulsion. Such an inlet geometry concepts employ side- wall compression to increase, in reasonable short distance, the air pressure prior combustion. The side-wall compression surfaces (i.e. fins) generate an oblique shock-wave that crosses one another and interacts with the boundary-layer developing on the windward of the fiJselage. The nature of such complex 3-D interactions can affect the performance of the inlet as well as the engine. If the physical principles governing these interactions are well determined and understood, then an active control system can be developed so that to reduce the risk of engine fail and optimise its performance. Note that the findings of this investigation are crucial for the design of effective thermal protection systems since these interactions produce high peaks of heating which can damage materials severely around concentrated areas where shock-waves hit surfaces. The main objective of this thesis is to predict accurately secondary separation flows and wall heat transfer under conditions of turbulent and separated flow, which has represented a challenging problem for computational fluid dynamists for the past thirty years. Steady RANS modelling has been carried out for a symmetrical double-sharp-fin configuration with an inclination angles from 7 degrees to 21 degrees, Mach 3.92 and Reynolds number RC5 = 3.08X105, aiming for comparison and improvement of wall heat transfer predictions. Grid refinement and turbulence modelling studies have been carried out carefully in order to improve previous numerical predictions against experimental measurements. Overall, current steady Reynolds Averaged Navier-Stokes computations with co-based Reynolds Stress Model (RANS-RSM) outperformed one- and two-equation conventional turbulence models as well as other numerical investigations carried out over the last three decades. My original contribution to knowledge focuses primarily on improving numerical prediction of wall heat transfer in supersonic/hypersonic side-wall compression inlets and deflected aerodynamic surfaces. Different methods of evaluation of the wall heat transfer, to improve the comparison with available experiments, have been proposed for both single- and double-fin configurations. Results are compared with experimental measurements and previous numerical studies. The most challenging numerical prediction of wall heat transfer coefficient in strong pressure gradient flows has been largely improved, for the first time, by adopting three approaches: (1) choosing a suitable turbulence model - the wall heat transfer coefficients peaks computed by RANS-RSM are in fact closer to experimental peaks (50% improvement) in comparison with other conventional two- equation eddy-viscosity turbulence models; (2) increasing the wall turbulent Prandtl number in region of high shear strain; (3) and finally, adopting a pressure-based correlation formula. The latter appeared to be the most effective method of predicting wall heat transfer coefficient, provided accurate wall pressure distributions being obtained by numerical simulations. Within the scope of this original research, complex flow structures are also numerically investigated in detail to verify and further examine, existing conclusions on the nature of incipient and secondary separation evolution at monotonic increasing shock strengths, for the single-fin configurations at Mach numbers 3, 4 and 5 and at beta fin’s deflection angles [if ranging from 9 degrees to 30.6 degrees. The nature of secondary separation will be explained at different regimes III-VI in condition of subsonic and supersonic transverse conical cross-flow. Computational Fluid Dynamics (CFD) analyses using conventional two-equation turbulence models are unable to capture secondary flow separations at moderate interaction strength - a phenomenon observed in experiments and believed to be associated with a ‘weakly-turbulent’ boundary-layer separation. I investigated this aspect in further details. In fact, RANS-RSM, due to its capability of reproducing correct level of turbulence kinetic energy (TKE), confirmed the presence of such a ‘weakly-turbulent’ state of transverse cross-flow in the near-wall regions underneath the main cross-flow vortex at moderate interaction strength (regime 111/] V). Computations revealed that the development of the secondary separation at early stage (regime III) is caused by the interaction of (1) the ‘conically-subsonic’ (Mn < 1) flow region of the transverse cross-flow developed from the primary reattachment (R[sub 1]) line with (2) the subsonic (M < 1) region of the near-wall secondary cross-flow which forms within the primary separation zone. Turbulence behaviour was also analysed, for the first time, in the reverse cross-flow in order to investigate the influence of the (laminar or turbulent) flow state in evolution of secondary separation phenomenon at increasing shock strengths. Remarkably, computed results are in good agreement with the conclusions of experimentalists. In fact, the secondary separation (S[sub 2]) cross- flow gradually disappears in transitional (laminar-to-turbulent) supersonic conical cross-flow regions (regimes IV and V), except at the regime VI, where S[sub 2] reappears, accompanied by a secondary reattachment (R[sub 2]) line, once the supersonic conical cross-flow becomes fully-developed turbulent. At this stage, the embedded normal shock-wave reaches the critical shock strength (xi[sub i]- 1.56) which is typically required to force turbulent separation. This study demonstrated numerically that the critical value xi[sub i]= 1.5 corresponds to the incipient secondary separation condition which is typical for the separated turbulent flows (regime V). A careful quantitative and qualitative analysis on the developments of the turbulence kinetic energy across the 3-D domain excitingly also confirms these findings. Thus, it was concluded that evolution of the secondary separation phenomenon at increasing shock strengths is influenced not only by the acceleration of the transverse cross-flow to conically-supersonic regime but also by some physical mechanisms that amplify the turbulence levels in the near-wall reverse cross-flow. One unique feature of the crossing-shock interaction at regime III; i.e. the secondary separation phenomenon, initially observed in the single-fin flow, has been successfully reproduced in a double-fin configuration by numerical computation using RANS-RSM. CFD predicted 3-D flow stream-surfaces showed that the initially weak secondary separation has been further strengthened in span-wise direction towards the central separated zone. Additional flow topology at stronger crossing-shock interactions has been also presented showing the evolution of surface flow-pattems at increasing shock strengths. To the author’s knowledge, the present study represents the first attempt to predict the evolution of secondary separation phenomenon in single- and double-fin configurations at different interaction regimes. Findings suggest that the classification originally made by Zheltovodov er al. for single- fin flows (hence for Swept-Shock-Wave/Turbulent Boundary-Layer Interaction, S-SWTBLI) can be also applied to double-fin configurations (thus for Crossing-Shock-Wave/Turbulent Boundary- Layer Interaction, C-SWTBLI).

Surgery for early onset scoliosis (EOS) often requires instrumentation which enables the pediatric patient’s spine to grow. The drawback of growing rods (Ellipse Technologies, USA) is the requirement of periodical extension (at least twice a year). In contrast, in growth- guidance sliding devices such as the Shilla (Medtronic, USA) or LSZ-4D (Conmet, Russia) the extension procedure is not necessary since only one or few fixtures are locked whilst other fixtures make it possible for rods to slide allowing growth of the spine. However, due to the absence of fusion in sliding devices increased rate of fractures of rods is possible. Additionally, movement of rods against fixtures may result in the generation of wear debris. Among traditional metallic materials used for such instrumentation titanium alloys are the most biocompatible and are widely used as fixtures material, while Nitinol, an alloy with Shape memory effect, is a promising material for rods due to having potential for more gradual and sustained correction associated with its shape memory effect and potentially reducing adjacent segment degeneration due to its super-elastic properties. The aim of this thesis was to investigate complications associated with implantation of growth-guidance sliding LSZ-4D in pediatric patients and to investigate the use of Nitinol and titanium alloy (Ti6Al4V) for this application. Analysis of retrieved components of LSZ growth-guidance sliding device (LSZ-4D) made from titanium alloy (Ti6Al4V) implanted in paediatric patients together with associated tissues showed metallosis which in some cases led to the development of complications including seromas and fistula formation. These complications occurred in 5 out of the 25 patients investigated. Another 4 patients encountered fatigue fracture of rods. The volume wear rate measured for the retrieved components of LSZ-4D was found to be 12.5 mm3 per year. In these 25 patients with implanted LSZ-4D devices there was a statistically significant increase in titanium and vanadium ions in the whole blood. With a view to replacing titanium alloy rods with Nitinol an investigation on the fatigue behaviour of Nitinol revealed that creating a microstructure which increased deformation due to a martensitic phase transformation improved high strain amplitude fatigue resistance of Nitinol, whereas precipitation of nanosize Ni-rich particles and decreasing of Ti4Ni2ox inclusions resulted in an increase in low strain fatigue resistance. The wear behaviour of Nitinol in comparison to titanium alloy was also investigated and showed that the wear resistance of Nitinol tested against titanium alloy (Ti6Al4V) in the simulated body environment is approximately 100 fold greater compared to titanium alloy (Ti6Al4V) and is similar to that of CoCr alloy. Nevertheless, Nitinol - Ti6Al4V combination still generates high volumetric wear associated with debris release from the Ti6Al4V component. Coating and treating the surface with TiN (titanium nitride), DLC (diamond like carbon) coatings and ion implantation of nitrogen ions in some instances reduced the wear. The deposition of a TiN coating only on the titanium component in a Nitinol - Ti6Al4V combination significantly improved the wear performance and this was associated with the protection of titanium component whereas the application of DLC improved the wear performance of both titanium and Nitinol. [on implantation or deposition of TiN or DLC coatings on both counterparts was found to be less effective. The current study indicates the importance and potential of reducing the reliance on titanium alloy by using Nitinol for patients with scoliosis and especially in those cases where relative moment of the fixtures is required, such as in growing patients.