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The work presented in this thesis is an investigation into vehicle bodyshell structural joints, with the aim of improving their stiffness. The bodyshell joint is defined to be an area or sub-structure containing the intersection of beam-type members, the behaviour of which may be defined by a matrix determined experimentally or analytically by using the finite element method. An actual bodyshell was tested on a suitably designed rig and the primary displacement modes affecting the steady state and vibration response of a bodyshell were identified and the relevant stiffness measured by using a special transducer. The joint rotational displacements were measured in these modes and the relative importance of the joints obtained. The joints were then modified by the addition of stiffening plates and the effect on the various stiffnesses noted. To assist the analyst, a similar study was performed on the effectiveness of the panels, such as roof, floor and rear quarter. A finite element beam model was established for the bodyshell and modified until a good approximation was achieved with respect to the experiments. Some practical modification of three selected joints cut from the bodyshell was done in order to improve their stiffness. A theoretical study of the influence of spot welding size and spacing on the stiffness of two plates was made. A finite element model of an actual body joint was established and the effect on stiffness of various modifications was observed.

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The crosswind sensitivity of a car is described as the sensitivity of a driver-vehicle system to vehicle movements provoked by wind influences. Research has shown that it is a contributory factor in accidents and that it is adversely affected by certain body shapes and by reductions in weight. Future legislation calling for a reduction in the amount of Carbon Dioxide produced by cars may well lead to this reduction in weight. Tests have been carried out on llth scale car models to compare the different results produced by static and dynamic tests. Although static tests are easier to perform, dynamic tests, in which the model is propelled across the wind tunnel, offer the advantage of an improved simulation of the skewed profile that the vehicle encounters at full scale. In these experiments a number of different skew profiles, turbulence profiles and model configurations including estates, hatchbacks and saloons, were tested at Reynolds numbers above 4x10⁵. The results showed that data from the more simple static tests were generally more conservative than those from the dynamic tests in a skewed profile up to approximately 30° of yaw. However, the static tests were unable to predict the peak yawing moment that occurs as a result of the transient flow over the model as it enters the gust. The dynamic tests also indicated oscillations in the flow over the rear end of the models in the hatchbacks with backlight angles of 22° and 36°, although less so in the latter. Other results suggested that there was an improved correlation between lift coefficients from different skew profiles, if the mean local velocity integrated over the height of the model was used to non-dimensionalise the data. Quality Function Deployment is not an appropriate framework to be used in the development of a complete vehicle but would prove useful if applied to the issue of crosswind sensitivity as a sub-component.

The KefB and KefC systems of E. coli are two separate potassium efflux systems that are regulated by glutathione and specific glutathione metabolites. The aims of this study were to clone and sequence the E. coli kefB structural gene and to investigate the subunit stoichiometry of the E. coli KefC protein. A further objective was to determine the distribution of the KefC class of transport system in a range of bacterial species, with the ultimate aim of cloning the kefC homologue from a highly divergent organism. Attempts to clone the kefB gene by various strategies proved unsuccessful; possible explanations for this are discussed. Analysis of the suppression of a kefC leaky mutation by plasmids bearing varying lengths of the wild-type kefC gene indicated that the mutant and wild-type KefC proteins interact in the membrane to form a structure that has intermediate properties. These observations are consistent with KefC functioning as an oligomer. Using a variety of techniques, it was demonstrated that the KefC class of transport system is widely distributed among Gram-negativespecies but is absent from all the Gram-positive bacteria tested with the exception of Staph. aureus. In addition the kefC homologue from Er. carotovora was cloned and DNA sequencing initiated. The cloned Er. carotovora kefC gene product was able to suppress an E. coli kefC leaky mutation, thus providing further evidence that KefC exists as an oligomer.