Environmental pressures are driving automotive manufacturers towards light weight cost efficient structures. Composite materials have been shown to display high specific energy absorption levels thus offering opportunities for mass reduction over conventional steel structures. Whilst composites display these specific advantages, the mechanisms by which energy is absorbed are more complex and are preventing widespread acceptance of composite structures. This work aims to further scientific understanding of the crushing process and provide realistic data for a wide range of processing conditions and commonly used materials. The main objectives of this study were to quantify the effect of industrial manufacturing conditions on the crush performance of composite structures, and to correlate the performance to a number of in-plane laminate properties. The manufacturing parameters considered are constituent material related (mould temperature, post-cure time and resin composition), interlaminar toughness related and process related (amount of binder and voidage). The work presented in the thesis reports the results of axial crushing experiments, in-plane and inter-laminar testing performed on composite parts made from glass reinforced polyester and vinylester resins. The preforms were made from 2 fabrics; a continuous filament random mat and a 0/90° non crimp fabric. All parts were produced by resin transfer moulding (RTM) under conditions which were representative of medium volume industrial processing. Constituent material results demonstrate clear advantages associated with the use of vinylester resin and that while relationships between all in-plane properties and the crush performance can be observed, the ultimate compressive stress is the most reliable indicator of this performance. Interlaminar toughness enhancement shows great promise for tailoring of the crush curve and increase in energy absorption of non-crimp fabrics. Results for the processing work are directly applicable to existing manufacturing and demonstrate the potential for real reductions in cycle time and increase in properties.

GPS and Inertial Navigation Systems (INS) are increasingly used for positioning and attitude determination in a wide range of applications. Until recently, the very high cost of the INS components limited their use to high accuracy navigation and geo-referencing applications. Over the last few years, a number of low cost inertial sensors have come on the market. Although they exhibit large errors, GPS measurements can be used to correct the INS and sensor errors to provide high accuracy real-time navigation. The integration of GPS and INS is usually achieved using a Kalman filter which is a sophisticated mathematical algorithm used to optimise the balance between the measurements from each sensor. The measurement and process noise matrices used in the Kalman filter represent the stochastic properties of each system. Traditionally they are defined a priori and remain constant throughout a processing run. In reality, they depend on factors such as vehicle dynamics and environmental conditions. In this research, three different algorithms are investigated which are able to adapt the stochastic information on-line. These are termed adaptive Kalman filtering algorithms due to their ability to automatically adapt the filter in real time to correspond to the temporal variation of the errors involved. The algorithms used in this research have been tested with the IESSG's GPS and inertial data simulation software. Field trials using a Crossbow AHRS-DMU-HDX sensor have also been completed in a marine environment and in land based vehicle trials. The use of adaptive Kalman filtering shows a clear improvement in the on-line estimation of the stochastic properties of the inertial system. It significantly enhances the speed of the dynamic alignment and offers an improvement in navigation accuracy. The use of the low cost IMU in a marine environment demonstrates that a low cost sensor can potentially meet the requirements of navigation and multi-beam sonar geo-referencing applications.

A surface shedding discrete vortex method has been developed for stimulating incompressible flows around pitching aerofoils. The method is able to predict both attached and separated flows, the latter typified by the formation and transport of large vortices. The structures of dynamic stall flow are well captured without the need for other means to predetermine the separation points. In contrast to most other vortex methods, the method presented herein can perform quantitative analysis. Throughout a wide range of incidence, the pressure distributions are smooth and the normal force and pitching moment are in good agreement with experimental data. The method is also able to predict the flow with external constraints for simulating the effects of wind tunnel blockage. In this regard quantitative results and flow structures have been obtained which are consistent with those expected. Following the review of previous work presented in the introduction, the mathematical formulation of the method is expounded. A velocity expression is theoretically derived for flows with both a moving inner boundary (aerofoil) and fixed external constraints (wind tunnel walls). To maintain both no penetration and no slip conditions, it is concluded that an external constraint parallel to the free stream can be modelled by placement of a constant vortex sheet along the boundary, and the introduction of distributed vortices next to the constraint to represent the boundary layer. The vortex sheet strength is equivalent to the free stream velocity while the strength of the vortices can be calculated in the same manner as for the internal boundary. This conclusion avoids the necessity of employing mirror vortices and iteration techniques in traditional models. The aerodynamic loads are computed from the pressure distribution. For the computation of surface pressures, the relationship between the pressure gradient and the rate of vorticity creation on the surface has been developed for a moving boundary.

Open cavity flow is that of most interest to researchers. The flow is typical to that found to exist in the bomb bay of the F-111 and is characterised by intense acoustic levels. A review of the work of previous experimental researchers is included for comparison with the findings of the present thesis. The flow physics indicate that a series of vortices travel downstream in the cavity and are driven by vorticity generated at the upstream lip of the cavity. When strengthened the downstream moving vortex influences the mass addition and expulsion at the trailing edge initiating a pressure wave which propagates upstream and sustains the process of completing the feedback lopp. These features are elucidated upon in the present thesis. The flow at Mach 0.85 and Mach 1.19 is analysed with only differences in the external stream being apparent for the higher Mach number case. The suppression of the acoustic environment is investigated by sloping the aft wall of the cavity. The results of the CFD study are used to examine why sloping of the aft cavity wall is successful. It is shown that the flow tends towards a steady state and the results are compared to the hypothesis of Heller and Bliss. This hypothesis is substantiated by the present simulations and in doing so the work demonstrates the ability of CFD to be used as a tool in conjunction with experimental methods to enhance the understanding of cavity flows. An area of cavity flows for which information is sparse is for the transitional cavity flows. A review of the literature shows that the 4 types of cavity flow exist at supersonic speeds and these are identified by the CFD. The results of the computational study are used to examine when the impingement and exit shocks, characteristic of closed cavity flow, collapse to form a single shock wave. This point is defined as L/Dcrit and occurs when the vertices of the separation and recompression wakes merge. It represents the boundary between transitional-closed flow and closed flow and the CFD predictions are compared to Prandtl-Meyer theory when investigating the position of L/Dcrit.

No description available.

This research project is about product development strategy and practice in the automobile industry. Specifically, it concerns the transformation of Rover Group body and tool development capability over four years from 1993 to 1997. A single Rover Body and Pressings organisation was created in 1991. It encompassed the functions of Body Engineering, Press Tool Engineering, and Press Tool Manufacturing. As Engineering Director the Author had the opportunity to directly influence a significant portion of the body product creation process. At the start of the research period the product development performance of Rover Body and Pressings was weak. Major investments in new press equipment could not depend on in-house die technology. Quality and cost delivery incurred customer dissatisfaction. Resulting from the research are three innovations: The Engineering Quality Assurance Procedure was implemented as a disciplined stage/gate quality management system. A focused manufacturing strategy was implemented for die manufacturing based on die size. A new engineering design methodology was established utilising the scientific principles of metal forming technology as an integrated element in the design process. These innovations were applied within the strategic framework of a new model describing a system view of the product creation process for body, at enterprise level. The new product development process strategy was partially applied to two new vehicle programmes. One vehicle has since been initiated and delivered from within the new framework. Strategic targets were defined for product development at Rover Body and Pressings covering product quality, development lead time, press tool cost and programme financial budget. The targets for quality and lead time were met during the research period. Although substantial progress is evident in physical performance the targets for press tool cost and programme budget were not met. The major elements of the product development strategy applied in this research remain in place. The transfer of the strategic model of concurrent engineering to a wider context was demonstrated by applying it as part of the Rover Group product development reengineering project.

In this thesis the author presents two areas of work; exploring the integration of Computational Fluid Dynamics (CFD) into engine design for Jaguar Cars Ltd and developing a novel 'mesh construction' method for making mesh generation both easy and fast. It is concluded that Jaguar can use CFD in the evaluation stage of the engine design process, although not in the concept stage of design. The CFD predictions are shown to be useful for detecting flow related faults and determining the general flow trends, but they should not be used as an absolute measure of the flow variables. The author has determined an efficient method for obtaining good quality meshes using commercial modelling and mesh generation software which requires a skilled CFD analyst. Steady flow analysis of an engine port and cylinder design could currently be completed in about six weeks using a high-powered workstation. The author recommends dedicated workstations for CFD analysis and training Jaguar's draughtsmen to create CAD models with computer analysis requirements in mind. The author's mesh construction program automatically joins two overlapping meshes or cuts one mesh from another. Whilst the program works well on the test cases considered, it is not at a stage for commercial exploitation. Further development is therefore recommended.

This thesis is concerned with the airborne noise reduction of agricultural tractor cabs. The characteristics of the noise radiated from a non-cab-equipped tractor have been evaluated and used in conjunction with the classical theories of airborne sound transmission loss to predict the airborne noise reductions of tractor cabs. An experimental cab has beep constructed and used to evaluate these predictions. The theoretical and experimental airborne noise reductions do not show a good agreement. This has been shown to be due to two ressons. Firstly, there are anomalies in the classical airborne sound transmission loss theory whereby the theoretical and experimental sound transmission loss spectra do not show good agreement. Secondly, one-dimensional standing wave resonances in the cab cavity have been shown to give rise to an irregular plateau in the experimental airborne noise reduction spectra. Anomalies have been shown to exist between airborne sound transmission loss theory and reverberant room transmission loss measurements. These have arisen because the theory has not hitherto considered panel flexure. Modifications have been introduced which take account of panel flexure and these show that the dependence of classical theory on the angle of incident excitation is false and angular dependence occurs on the transmitted side of the panel, giving rise to a coincidence effect on the transmitted side which is independent of the angle of incidence. These modifications give rise to complete qualitative explanation of the shape of empirical airborne sound transmission loss spectra. Quantitative modifications have not been introduced because of lack of information regarding the angular nature of the transmitted waves.

No description available.

No description available.