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This thesis investigates how current hybrid bus technology can be improved, through the application of a waste heat recovery system capable of operating on a hybrid bus. At present modem internal combustion engines reject the majority of fuel energy consumed as waste heat through the engine coolant and exhaust streams. By employing innovative technology it is proposed that this, otherwise wasted, heat can be captured and converted to power or to provide useful heating or cooling on the hybrid bus. This recaptured heat will therefore allow an improvement in fuel consumption and a reduction in exhaust emissions. The research carried out in this thesis attempts to determine if the fuel economy of a hybrid bus can be improved by using a waste heat recovery system. The work also aims to discover which type of system is the most suitable for installation on such a vehicle. To achieve this, the modeling of system performance, as well as the design and testing of a fully operational waste heat recovery system on a hybrid bus is presented. The result of the system modeling is benchmarked against the actual, installed system, experimental results which were conducted at M ill brook proving ground U. K. A novel model of an expander was also developed during the research. This model was compared to test data obtained during experimental testing of an expander at Queen's University Belfast. The purpose of the model was to gain a greater understanding of expander leakage and performance while operating in a waste heat recovery system.

The purpose of this research into Design Paradigms in Car History is to evaluate how production car design has changed over the last hundred and twenty-five years or so, using numerical analyses of specific cars, which act as exemplars. This evaluation should lead to a better understanding of car design history and how car designers think. Design thinking can be evidenced from how products have changed over the course of time. Design paradigms have been used to produce a structured analysis of these products (cars) to develop a more holistic understanding of design history than may be available from a purely narrative approach. The research sought to answer some basic questions, including what are design paradigms, when did specific ones appear, and when, why and how quickly did they change? A positivist, quantitative analysis was carried out, analysing over 500 cars from 1878 to 2013 for layout and form design, using a categorical principal components analysis. Timelines and maps were produced identifying paradigms, changes and timescales. A complementary qualitative approach was taken, interviewing car experts – historians, designers, industry leaders and enthusiasts – to identify their constructs on car history and design. Methods used included affinity diagrams and a novel use of repertory grids. Car design paradigms were identified from static layout variables, from about 1904 to 1934, from the mid-1970s onwards, and less pronounced from the late 1930s to the 1980s. These show tight clustering of features. Stepwise changes tend to occur between paradigms. Form changes more smoothly, but still indicates likely dates and paradigmatic thinking. Constructivist analysis identified further wide-ranging paradigms, including societal changes, technology, political and economics. The main conclusion of this research was that design paradigms not only exist, but they can also be measured and this measurement can improve historical understanding. This finding will benefit not only those interested in cars and their history, e.g.museum curators and those training future designers, but also other researchers, who could use a combination of both analytical and constructivist processes, in particular repertory grids, to develop their subject thinking and understanding of historical processes.

The work in this thesis is aimed primarily at developing a vehicle ride simulation program based on a generalised vehicle model formulation to evaluate the effect of various system parameters on the ride quality of a vehicle, and secondly to develop an optimisation scheme for determining the optimum setting of suspension parameters as related to ride comfort. The simulation program can accommodate the non-linearity of the suspension components such as tyres, shock absorbers and suspension springs. Based on a twin tube shock absorber in production, a damper model was developed. This damper model was included in a vehicle model and was run in parallel with the simulation program. A variety of vehicle models were developed and simulated in the time domain with various road obstacles such as half-sine, half-circle and ramp, and the results are presented. In order to improve the accuracy of the simulated response in the time domain, an attempt has been made to find the wheel envelope as it passes an obstacle. Based on a real car in production, two different vehicle models were developed and simulated in the frequency domain and the simulated responses were compared with those obtained from experiments. A series of tests were carried out on a test vehicle on the ride simulator and the transient responses were compared with those obtained from the simulation program. Attempts were made to improve the accuracy of the simulated response by inclusion of bilinear damper models in the simulation process. Several studies has been made to investigate the effect of various vehicle system parameter on the overall ride performance.

Motor car crosswind stability can be adversely affected by reductions in both vehicle mass and drag coefficient. As these are two likely results of future developments the importance of research into vehicle aerodynamic stability is set to increase, moreover, there is evidence that transient effects will be the critical. An experimental facility has been designed and constructed and tests have been carried out to investigate the implications of simulating dynamic flow-fields. Vehicle models of approximately 1/6th scale have been propelled along a test track, in the laboratory, to pass through a simulated crosswind gust of variable resultant yaw angle. Force and moment measurements have shown the aerodynamic inputs to be highly repeatable, though the technique has been restricted somewhat by the presence of mechanical "noise". Additional dynamic yaw experiments were conducted on a bluff-body model mounted in the College of Aeronautics' Oscillatory Facility. In some ways this technique is not as realistic as the Crosswind Track in its simulation of the full scale flow, however, despite its simplicity valuable aerodynamic data was derived from this test. Quasi-static tests have also been conducted and demonstrate that for certain model configurations a clearly defined yaw angle range exists where two different wake flow-structures are possible. At any given yaw angle, the dominant structure is determined by the flowfield history - essentially the direction in which the model is moved. This causes hysteresis in the forces and moments generated. In such a situation the flow is referred to as being bi¬stable. Both track and dynamic yaw tests indicate that the bi-stable flow phenomenon, witnessed in quasi-static experiments, can influence the dynamic forces and moments measured on a model. The flow structures associated with bi-stability are viscous-dominated and the slow development of viscous loads can be an important feature. It is possible that various vehicle configurations could induce bi-stable flow. If such flow behaviour is apparent then quasi-static forces and moment measurements will not provide an adequate engineering estimate of the transient aerodynamic loads. In this event it is imperative that the automotive engineer conducts investigations into the vehicle's dynamic performance.

This thesis investigates the characteristics and performance of a new type of active suspension for cars through modelling, simulation, control design and experimental testing. The Series Active Variable Geometry Suspension (SAVGS) concept is first put in context by reviewing the history and current trends in automotive suspensions. Its potential is then critically evaluated and work is carried out to maximise its performance for various suspension functions. A multi-model multi-software modelling and simulation approach is followed throughout the thesis in order to cross-check and substantiate simulation results in the absence of experimental data. The simpler linear models are used to inform the selection of suitable parameter sets for the case studies, to synthesise control systems and to qualitatively validate the more complex, nonlinear multi-body models. The latter are developed as a platform to virtually test the system and its control algorithms. When possible, these tests are based on standard open-loop test manoeuvres and on standardised external disturbances. The SAVGS-retrofitted suspension displays a very nonlinear behaviour, which is at the same time a liability and an opportunity from the point of view of control. Nevertheless, different linear control techniques are effectively applied to improve various suspension functions: PIDs are applied to the lower frequency suspension functions such as mitigation of chassis attitude motions, and the H∞ framework is applied to the higher frequency suspension functions such as comfort and road holding enhancement. In all cases, a cascade control approach is employed, and mechanisms are implemented to ensure that physical and design actuator constraints are always respected. This thesis also covers the design and construction of a quarter-car experimental test rig facility. Step-by-step recommendations for its refinement as well as a testing plan are also outlined.

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The impact of human activity on the environment is significant. One way to reduce our carbon footprint is to decrease the mass of passenger vehicles, improving fuel efficiency. In addition, the use of recycled materials can reduce environmental impact further. The aim of this project is to fabricate and evaluate novel recycled carbon fibre reinforced aluminium as a lightweight material for passenger vehicles. Recycled carbon fibre reinforced aluminium materials were fabricated by gas pressure infiltration. The infiltration behaviour of the preforms was quantified by mercury intrusion porosity, compared to other preform types, and compared to composite materials fabricated at different pressures. Recycled carbon fibre reinforced aluminium materials can be fabricated by gas pressure infiltration, using less than 12 bar gas pressure, resulting in fibres occupying approximately 11% of the material volume. A sodium silicate binder was utilised in an effort to increase the fibre packing fraction and improve preform handle-ability. Silicon was added to the aluminium matrix to inhibit the formation of aluminium carbide during fabrication at the fibre/matrix interface. Although this was not successful, the composite materials containing silicon exhibited reduced porosity and fibre breakage, and no aluminium carbide was observed after up to 4 hours of heat treatment. Nickel-coated carbon fibre was used to improve the wetting behaviour between the fibres and the matrix, which reduced the required pressure for infiltration with aluminium by five times. The mechanical properties of the composite material were evaluated using wear testing and a novel small-specimen creep test. The testing specimen size may not be representative of the composite material as a whole, as in most cases, the addition of carbon fibres had a deleterious effect on the mechanical properties of the material.

The high cost of raw materials, high labour costs and lengthy cycle times have limited the use of conventional ply-based composites in the automotive industry. This thesis seeks to identify the potential of using low cost discontinuous fibre composites (DFCs) for structural applications. Properties of DFCs are governed by the degree of homogeneity of the reinforcement and discontinuities at the fibre ends, which cause stress concentrations; thereby limiting the mechanical performance of the material. This work focuses on material characterisation of laminates moulded from discontinuous carbon fibre preforms manufactured by a robotic spray process. Through the culmination of this work, a suitable design methodology for automotive applications has been identified. Design procedures for aerospace have also been considered. An analytical model has been developed to determine the tensile stiffness and strength of a discontinuous carbon fibre preform composite. The model can be used within automotive and aerospace design methodologies to define material properties, but a number of other factors must be considered. Areal mass of the preform has been identified as the governing factor in achieving target compaction levels. Poor homogeneity in thin parts prevents the ability to achieve high volume fractions, which determines mechanical performance. It has been demonstrated that the matrix has a greater influence on the properties of DFCs when compared to continuous fibre composites. Toughened resins were particularly effective in improving tensile strength of DFCs that exhibited poor homogeneity. Damage tolerance of DFCs has been evaluated through open-hole and compression after impact testing. Higher property retention was observed compared to continuous fibre equivalents. Greater damage tolerance of DFCs could lead to increased weight-saving in structural applications. However, current safety factors based on conventional laminates may be too conservative and could lead to over-engineering thus limiting the potential of the material.

Reclined seats in transport suggest luxury and comfort, but a review of the literature revealed little study of how backrest inclination influences the discomfort caused by vibration of a seat or a backrest. This thesis seeks to advance understanding of the influence of backrest inclination on vibration discomfort and provides a model for evaluating vibration discomfort and metrics for optimising seats with different backrest inclinations. Vibration discomfort depends on the direction and location of vibration input to the body. Subjects used magnitude estimation to judge vibration magnitudes from thresholds of perception up to 2 ms-2 r.m.s. at the 11 preferred 1/3-octave centre frequencies from 2.5 to 25 Hz. The first two experiments determined absolute thresholds and discomfort with x-axis backrest vibration (Experiment 1) and z-axis backrest vibration (Experiment 2) with four backrest inclinations (0°, 30°, 60°, and 90° from vertical). The third experiment investigated discomfort with vertical seat pan vibration and five backrest conditions (no backrest and backrest inclined to 0°, 30°, 60°, and 90°). With x-axis vibration of the back, inclining the backrest had similar effects on thresholds and equivalent comfort contours. Thresholds increased at frequencies from 4 to 8 Hz with increasing inclination of the backrest. With inclined backrests, 40% greater magnitudes of vibration were required from 4 to 8 Hz, to cause discomfort equivalent to that with the upright backrest. Frequency weighting Wc in current standards predicted discomfort and perception of x-axis vibration of the upright backrest (0°) but weighting Wb was more appropriate for inclined backrests. Frequency weighting Wd was appropriate for both discomfort and perception of z-axis vibration of the back at all backrest inclinations. With vertical seat acceleration, the frequency of greatest sensitivity decreased with increasing vibration magnitude. Compared to an upright backrest, around the main resonance of the body the vibration magnitudes required to cause similar discomfort were 100% greater with 60° and 90° backrest inclinations and 50% greater with a 30° backrest inclination. The fourth experiment investigated whole-body vertical vibration on a rigid seat with no backrest and with four backrest inclinations. With an inclined backrest, discomfort caused by high frequency vibration increased at the head or neck but discomfort at the head or neck caused by low frequencies (5 and 6.3 Hz) reduced. With inclined backrests, the procedures in current standards overestimate overall discomfort at frequencies around 5 and 6.3 Hz but underestimate discomfort caused by frequencies greater than about 8 Hz. The final experiment investigated a model for predicting vibration discomfort with three compliant reclined seats. At each frequency, the measured seat dynamic discomfort, MSDD (the ratio of the vibration acceleration required to cause similar discomfort with a compliant seat and a rigid reference seat), was compared with seat effective amplitude transmissibility, SEAT value (the ratio of overall ride values with a compliant seat and a rigid reference seat using the weightings in current standards). The compliant seats increased vibration discomfort at frequencies around the 4-Hz resonance but reduced vibration discomfort at frequencies greater than about 6.3 Hz. The SEAT values provided appropriate indications of how the foam increased vibration discomfort at some frequencies but decreased vibration discomfort at other frequencies. Differences between the SEAT values and the measured seat dynamic discomfort are consistent with the need for different frequency weightings when the body is supported by an inclined backrest. An empirical model was evolved from the experiments for predicting vibration discomfort with reclined seats. It is concluded that reclining a backrest will tend to be detrimental at frequencies greater than about 10 Hz with greater discomfort in the head or neck induced by vibration of the backrest. At frequencies around 5 and 6.3 Hz, reclining a backrest can reduce discomfort.