Fast heat dissipation from brake discs is sought in current vehicles, where high power braking duties demand harmonic combination of strength, (undamped) disc mass and cooling abilities for a wide speed range. This work analyses the convective heat dissipation from ventilated brake discs and proposes means for its optimisation. The focus of research is the ventilation geometry of a standard brake disc with an outer diameter of 434mm and radial channels of 101mm in length. After analysing in detail data calculated with CFD simulations and from experimental work for various ventilation patterns, a parameter relating the local channel-averaged convective heat transfer coefficient to channel circumferential width, and radial location was derived. This new numerical parameter termed Flow Index, depicts graphically the link between channel geometry (width and position) to the heat transfer coefficient level attained. The FI was not only used as a tool to analyse the convective performance of conventional and new ventilation geometries, but it also allowed clear identification of changes necessary in the channel width in order to improve its convective heat transfer coefficients. New, optimised for convective heat transfer, ventilation geometries designed with the FI were achieved in this Thesis. Industrial (patenting) and academic applications are foreseen from the results of this Thesis and its future activities. Also, the work developed in this Thesis gives path and supporting frame for future research in the field of brake disc convective heat dissipation.

Chapter 1 presents a literature review concerned with the background to trailer steering, rollover prevention, vehicle parameter and state estimation, and integrated steering and braking. Chapter 2 presents simulation results of various brake actuation events on articulated vehicles with path following control. It is shown that the vehicle is stable under braking with path following control provided the Anti-lock Braking System is functioning. Active trailer steering can compensate the changing direction of trailer body caused by the braking forces and thus maintain the vehicle’s yaw stability. Chapter 3 and 4 present a strategy for estimating vehicle parameters and states. Chapter 5 develops an optimal active trailer steering controller at high speeds and a PID controller at low speeds. Simulations show that the active trailer steering controller can reduce lateral acceleration significantly, while maintaining acceptable path error. The active steering vehicle improves the roll stability by reducing the lateral acceleration of trailer CoG up to 27% while maintaining path tracking performance as good as a passive vehicle at high speeds. It is more manoeuvrable at low speeds, reducing the tyre wear and causing less road damage.

One potential interaction between environmental and safety goals in transport is found within the vehicle fleet where fuel economy and safety impose conflicting requirements on vehicle design. Larger and heavier vehicles have a better secondary safety performance during a crash. On the other hand, they are associated with higher levels of fuel consumption and emissions. This issue has generated debate amongst researchers and policy makers when formulating policies to improve the environmental performance of the road transport system. An extensive review of literature reveals that arguments has often been based on either little research evidence, or research that has inadequacies in the applied methodologies. This research investigates the safety consequences of changes in vehicles mass within the vehicle fleet aimed at increasing fleet fuel economy. The partial effects of mass on fuel consumption rate and secondary safety performance were estimated using a cross-sectional analysis of mass within the British passenger car fleet. Estimation results confirmed that fuel consumption increases as mass increases and were different for different fuel and transmission types. It was shown that vehicle mass has both protective and aggressive safety effects where vehicle size only tends to have protective effects; these were estimated using a novel methodology based on a detailed analysis of two-car crashes. The estimated relationships were used to investigate partial safety and environmental effects of changes in mass distribution within the fleet using an introduced incremental approach. Results generally showed that the relationship between fuel economy and safety performance in vehicle design depends on the characteristics of the vehicle fleet, and in particular, mass distribution. It was shown that an informed change in the mass distribution not only imposes no trade-off between the fuel economy and safety goals, but also could lead to a desirable outcome in both aspects.

To meet the demands for safety and passenger comfort, modem passenger cars offer more and increasingly sophisticated electrical and electronic systems. The wiring harnesses that support such systems become too large, complex and heavy, when designed for a conventional electrical architecture based on 14 volts, posing several challenges to automotive manufacturers. Alternative electrical architectures based on 42 volts and in-vehicle multiplexing promise to reduce the size and weight of the wiring harness, but these architectures are yet to be fully developed and standardized. In the near term, alternative wiring solutions have gained the interest of automotive manufacturers. Small flexible printed circuits (FPCs) have previously been integrated into automotive instrument clusters. The benefits of reduced weight and space requirements of such FPCs compared to a wire harness has fuelled an interest in much larger FPCs as substitutes for the Instrument Panel and door harnesses in high-volume production cars. This research investigates the materials typically used in FPC manufacture, for applicability within a passenger car.

The present thesis examines the quantitative characteristics of driver braking and pedal operation and discusses the implications for the design of braking support systems for vehicles. After the current status of the relevant research is presented through a literature review, three different methods are employed to examine driver braking microscopically, supplemented by a fourth method challenging the potential to apply the results in an adaptive brake assist system. First, thirty drivers drove an instrumented vehicle for a day each. Pedal inputs were constantly monitored through force, position sensors and a video camera. Results suggested a range of normal braking inputs in terms of brake-pedal force, initial brake-pedal displacement and throttle-release (throttle-off) rate. The inter-personal and intra-personal variability on the main variables was also prominent.

Hybrid stress method is used in the development of beam, plate, cylindrical shell and doubly-curved shell finite elements. The behaviour and convergence of the hybrid elements are dependent on the coefficients appearing in the assumed stress field. This effect is investigated for the elements considered, and optimum stress assumptions are obtained.

The automotive industry has long relied on testing powertrain components in real vehicles, which causes the development process to be slow and expensive. Therefore, hardware in the loop (HIL) testing techniques are increasingly being adopted to develop electronic control units (ECU) for engine and other components of a vehicle. In this thesis, HIL testing system is developed to provide a laboratory testing environment for continuously variable transmissions (CVTs). Two induction motors were utilized to emulate a real engine and vehicle. The engine and vehicle models, running in real-time, provide reference torque and speed signals for input and output dynamometers, respectively. To design torque and speed tracking controllers, linear models of the motor and drive systems were firstly identified from the test results. Feedforward controllers were then designed according to the inverse dynamics of the identified models. Because of the existence of unstable zeros in the model, design effort was focused on the stability and causality of the inverse process. Digital preview filters were formulated to approximate the stable inverse of unstable zeros as part of the feedforward controller. Normally, future information of input trajectory is required when implementing the digital preview filters, which makes the feedforward controller non-causal. Since the engine and vehicle model require current information to calculate the next output and no future value can be provided in advance, the application of non-causal digital controllers was limited. A novel method is proposed here to apply non-causal digital controllers causally. Robustness of the controllers is also considered when the two motors are coupled and the gear ratio between them was changed. The proposed coupled control method was tested and verified experimentally by using a manual gearbox before recommending its use for a CVT testing. A multifrequency test signal as well as simulation results of a whole vehicle model were used as torque and speed demand signals in the experiments. A HIL testing case was also presented. Frequency and time domain results showed the effectiveness of the method under both testing procedures to fully compensate for the dynamics of both actuators.

Biodiesel is an environmentally friendly alternative diesel fuel consisting of the alkyl esters of fatty acids which are expected to play a significant role in reducing overall CO2 emissions. Biodiesel is produced commercially by a chemical reaction called transesterification which is a chemical process to lower the viscosity of the vegetable oils. Since Biodiesel is an oxygenated, sulfur free fuel, it typically reduces engine out emissions except for the oxides of nitrogen (NOX). The chemical and physical properties of the fatty acids, as well as the effect of molecular structure, determine the overall properties of biodiesel fuel. Investigations into the impact of FAME properties on diesel engines are highly topical, as higher blends of biodiesel are introduced. The aim of this work is to perform a comprehensive study on the use of biodiesel fuel in production diesel engines, and its impact on emissions, performance and fuel consumption. This thesis has shown that the use of biodiesel fuel reduces the engine out emissions of CO, HC and PM (except at sub-zero temperatures), and causes a slight increase in NOX emissions and fuel consumption compared to baseline diesel fuel. However, the lower exhaust gas temperatures seen when using biodiesel blends leads to reduced catalyst conversion efficiency and an adverse effect on tailpipe emissions. The cylinder pressure and rate of heat release profiles of biodiesel blends are very similar to those of baseline diesel fuel when similar torque is demanded from the engine with relatively similar start of combustion for the main charge. Biodiesel blends show a slightly quicker rise in the rate of heat release and higher peak values compared to baseline diesel fuel. In the case of matched pedal positions, the ignition delay time decreases slightly with biodiesel use at lower engine load conditions compared to baseline diesel fuel. The sensitivity of engine performance and emissions with B25 is more pronounced for EGR rate, rail pressure, and main injection timing variations than for baseline diesel fuel. Finally, an adverse thermal impact of using biodiesel fuel on the performance of diesel oxidation catalyst was observed compared to baseline diesel however, no solid evidence of exhaust gas HC speciation effects was found.

Most downsized gasoline engines currently in the market place appear to have a ‘downsizing factor’ of approximately 30% to 40%. However, as concerns regarding fuel efficiency and emission legislations increase, more aggressive downsizing may have to be introduced. This, although can improve fuel efficiency and enhance power density of a gasoline engine further, has some challenges that must be addressed. Large backpressure is one of the most important aspects that needs to be improved for a highly downsized gasoline engine, especially if a Regulated 2-stage system is considered. The Divided Exhaust Period (DEP) concept is an alternative gas exchange process, where two exhaust valves from each cylinder separately function, with one valve leading the blow-down pulse into the turbocharger turbine, while the remainder of the exhaust mass flow bypasses the turbine through the other valve. The simulation results suggest that by adopting the DEP concept, the full-load Brake Specific Fuel Consumption (BSFC) and the stability of the engine were all improved due to the fact that the DEP concept features a better gas exchange process and improved combustion phasing. The part-load BSFC could also be reduced by using the scavenging valve to extend the ‘duration’ of the exhaust valve (thus reducing the re-compression effect) and to achieve internal exhaust gas recirculation (EGR) through reverse flow. However, this depends on the authorities of the scavenging valve timing (and piston clearance) and the combustion stability (EGR tolerance). Driveability issue and poor fuel efficiency in some engine operating regions of a conventional fixed-ratio positive-displacement supercharging system also need to be mitigated. A continuously variable transmission (CVT) driven supercharging solution, with the capability to decouple the supercharger speed from the engine speed, has the potential to provide the full-load BSFC improvement and to enhance the driveability performance, with a minor penalty in part-load BSFC. Both the simulation and experimental results have demonstrated its advantages over its fixed-ratio positive-displacement counterpart. The high-load fuel consumption can be improved by as much as 17.5%, and the time-to-torque performance can be improved by up to 37%. The low-load BSFC was only degraded by up to 2%, however, given that there was no clutch fitted for the CVT driven supercharging system, a better transient performance is anticipated.

The dynamic performance of a hydrostatic transmission with a variable delivery pump used for speed control is predicted using a simple mathematical model. A detailed analytical study and experimental determination of the performance of the pump and motor is carried out. The analysis of the transmission is then extended to take into account the pump and motor slip and torque losses, and the prime mover droop, by employing signal flow techniques. The results of theoretical predictions of dynamic performance made using this technique were compared with those from an extensive test programme employing electro-hydraulic test techniques carried out on a typical hydrostatic drive. The signal flow analysis improved the prediction of the transmission dynamic performance over that of the simple mathematical model, but it was found that errors of up to 40 per cent were occurring as many of the loads employed could not be accurately represented by simple mathematical models. A vector approach was adopted using experimentally determined load loci that provided a correlation of within 5 per cent of the experimentally measured response by using the isentropic tangent bulk modulus of the oil obtained from the results of the most recent static tests carried out by the oil manufacturer. Mean return line pressure, restricted boost system, and flexible pipeline effects were evaluated by the vector locus technique and verified by an experimental programme. The work was extended to investigate aeration effects by developing the test facility to enable the transmission to be supplied with oil with an artificially high quantity of gas dissolved in it. No significant effects upon the transmission steady state or dynamic performance could be determined.