Automotive friction materials are multi component composites in which fibrous materials play a fundamental role. Modern friction formulations have been developed around asbestos fibres, a heavily used material before legislation outlawed its use in the 1980’s. The replacement adopted by the friction industry was aramid, a high performance, high cost synthetic fibre. The work in this thesis investigates the role of aramid fibres in an economy friction material from the early mixing stages in manufacture using mechanical and optical analysis techniques through to the friction and wear performance of brake pads by employing instrumented friction and wear machines. Experimental procedures were designed and employed to quantify the performance of aramid pulp within the friction formulation as a function of volume fraction. Investigation showed a hierarchal fibre structure produced by an inherent molecular structure that encourages fibrillation producing complex fibre morphologies. This physical structure has been identified as fundamental to the success of aramid pulp in friction materials as the fibre network readily entraps small particles aiding the manufacturing process of friction materials. A structural model has been developed to describe both the particle retention performance of aramid fibres and the bulk structure of the pulp as a function of fibre geometry. A dynamic mechanical test was used to measure the bulk elastic properties of fibre networks to assess their suitability as processing fibres in friction materials and providing a novel analytical technique for the friction industry. Hemp, flax and jute are examples of high performance natural fibres that offer a significant cost saving over aramid, representing candidate replacements. Various natural fibres were trialled in friction formulations as direct replacements and also blended with aramid pulp. The results are compared to the baseline specification produced for aramid pulp allowing the suitability of natural fibres in friction materials to be discussed.

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During driving on rough roads, rattle noise may emanate from (electric power) rack-and-pinion steering gears as a result of reverse feedback from the road. This project is in collaboration with a German steering system manufacturer and aims to develop a methodology facilitating identification and quantification of transient structure-borne sound sources within electrical steering systems. To achieve this aim, a conceptual source-path-receiver model has been developed that discloses the theoretical locations and associated mechanisms of all possible transient sound sources inside the steering gear. This information forms the basis for a subsequent measurement step which is required to experimentally quantify the strength of each individual source. The measurement approach is based on a time domain equivalent of the in-situ blocked force method; thus facilitating independent source characterisation on the fully assembled structure. The time domain (TD) approach relies on a robust inversion routine that uses an adaptive algorithm to simultaneously reconstruct multi-channel (blocked) force signatures from operational responses and the corresponding impulse response functions both measured (in-situ) on the (assembled) structure. The TD inversion routine is derived from the least mean square (LMS) algorithm which is widely used in adaptive filter design. The accuracy and sensitivity of the TD inversion routine is elaborated and compared to the standard frequency domain inverse method using simple numerical examples. Its general applicability for sophisticated technical structures is evaluated by example of an electric powered steering system being subjected to artificial excitation. The use of the TD approach for characterisation of transient structure-borne sound sources based on the blocked force method is discussed and different procedures to improve the force estimation accuracy are proposed. These procedures can be classified into methods that (i) help to evaluate the quality of pre-measured frequency response functions (FRFs) which are required to set up the (inverse) system model, (ii) measurement routines that may help to improve future FRF measurements conducted in-situ, i.e. whilst the steering gear is connected to a special rattling test bench, (iii) correction strategies to separate contributions from known (external) structure-borne sound sources different from the desired (internal) rattling sources and (iv) criteria that in theory allow for monitoring the performance of the iterative TD inversion routine precisely. Finally, the developed methodology is used to identify and quantify rattle sources within a steering system under realistic testing conditions.

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An investigation into improving a design of the flux switching motor for use in an automotive application is presented. This concentrates on developing computer simulation tools to model the motor performance effectively and hence enable the development of an alternative design.;The flux switching motor is introduced as a relatively new type of brushless drive with a high level of robustness and low cost power electronics. These properties in particular make the flux switching motor well suited to the automotive industry, where reliability and cost are paramount.;This thesis details research carried out to develop a new circuit simulation of the motor and its power electronics using the program PSpice. The model developed here is then used as a tool to investigate the performance of the motor. This is used in conjunction with static finite element analysis performed in the program Opera and later on with time stepping finite element analysis also in Opera. These simulation tools are tailored to model the flux switching motor accurately and aid with the improvement, in terms of torque production, of the design.;The models are used to produce a new motor design making use of 12 rotor teeth instead of the 4 teeth originally presented. This design shows promise in early static simulations with the potential for higher power due to a higher operating frequency, although high iron loss indicates this may be outweighed. However, time stepping simulation shows that torque production is actually lower than the original 4 tooth design due to lower flux in the small rotor teeth.

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This thesis presents the formal verification of a clock synchronization algorithm in a distributed communication system. The communication system is inspired by the demands of the automotive industry and based on the FlexRay standard. The work is part of the Verisoft automotive subproject. The distributed system consists of hosts interconnected via a communication bus. We introduce a schedule that provides deterministic communication delays based on a clock synchronization algorithm which deals with clock drift. We present the hardware specification of the bus controller parts related to the scheduling correctness. Furthermore, we extend the formalism from knapppaul to state the correctness theorem in a clean mathematical way. This formalism also involves theories about asynchronous communication. Finally, we present a mathematical-style proof for the correctness of the clock synchronization mechanism and introduce the principles behind the straight forward formalization of this proof which we have carried out in the Isabelle/HOL theorem prover.

Racing car suspensions are a critical system in the overall performance of the vehicle. They must be able to accurately control ride dynamics as well as influencing the handling characteristics of the vehicle and providing stability under the action of external forces. This work is a research study on the design and optimisation of high performance vehicle suspensions using inerters. The starting point is a theoretical investigation of the dynamics of a system fitted with an ideal inerter. This sets the foundation for developing a more complex and novel vehicle suspension model incorporating real inerters. The accuracy and predictability of this model has been assessed and validated against experimental data from 4- post rig testing. In order to maximise overall vehicle performance, a race car suspension must meet a large number of conflicting objectives. Hence, suspension design and optimisation is a complex task where a compromised solution among a set of objectives needs to be adopted. The first task in this process is to define a set of performance based objective functions. The approach taken was to relate the ride dynamic behaviour of the suspension to the overall performance of the race car. The second task of the optimisation process is to develop an efficient and robust optimisation methodology. To address this, a multi-stage optimisation algorithm has been developed. The algorithm is based on two stages, a hybrid surrogate model based multiobjective evolutionary algorithm to obtain a set of non-dominated optimal suspension solutions and a transient lap-time simulation tool to incorporate external factors to the decision process and provide a final optimal solution. A transient lap-time simulation tool has been developed. The minimum time manoeuvring problem has been defined as an Optimal Control problem. A novel solution method based on a multi-level algorithm and a closed-loop driver steering control has been proposed to find the optimal lap time. The results obtained suggest that performance gains can be obtained by incorporating inerters into the suspension system. The work suggests that the use of inerters provides the car with an optimised aerodynamic platform and the overall stability of the vehicle is improved.

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The increase in number of diesel powered vehicles has led to greater concern for the effects of their exhaust emissions. Engine manufacturers must now consider using diesel particulate filters to make their engines meet the legislated limits. Diesel particulate filters can remove more than 95% of the particulates from the exhaust flow but require cleaning, known as regeneration. This thesis describes the research and optimisation of the Autoselective regeneration system for cordierite wall flow diesel particulate filters. The novel Autoselective technology uses an atmospheric pressure glow discharge plasma to selectively oxidise particulate matter (soot) trapped within the filter. The aim of this research was to produce a regeneration system that can operate under all exhaust conditions with a low energy demand and no precious metal dependence to compete with the numerous pre-existing technologies. The effect of discharge electrode type and position on regeneration performance has been investigated in terms of regeneration uniformity, power requirement and regeneration rate. The results showed that the electrode orientation had a large effect on regeneration distribution and energy demand. The electrode capacitance and breakdown voltage was shown to affect the choice of power supply circuit because not all power supply topologies were suitable for powering electrodes with >100 pF capacitance. A number of power supplies were designed and tested, a voltage driven resonant transformer type supply was shown to be optimal when used in conjunction with a swept frequency. The current and frequency ranges of electrical discharges were continuously variable, and their effect on discharge regeneration performance was studied. The results showed that the discharge frequency had no effect on the regeneration process but did affect spatial distribution. An optimised resonant transformer power supply was designed that was ideally suited for the electrodes used. A novel power modulation strategy, which used a switching frequency phase locked to the ~ iii ~ modulating frequency, was employed which extended the operating range of the discharge to below 10 mA for electrode separations > 7.5 mm. The heat flows within the filter and discharge during regeneration were analysed and the filter damage process was linked to the heat released by the discharge inside the filter wall. Other filter materials were compared based on the findings and Mullite ceramic was identified as a potentially better filter material for Autoselective regeneration. The filtration efficiency is important and was observed to be affected by the Autoselective process. The effect of the discharge on filtration efficiency was studied and the mechanism of particulate re-entrainment was identified as a combination of electrostatic and electro-acoustic forces. The Autoselective technology was successfully implemented in both flow-rig and on-engine tests. Results showed significant reduction in back-pressure for power inputs of ~ 500 W. The understanding of the Autoselective regeneration system has been improved and the research resulted in a novel method of filter regeneration.