In this work, an ANN program has been developed to predict the indentation P-h curves with known properties. An interactive parametric FE model and python programming based data extracting program has been developed and used to develop data for the ANN program. Two approaches have been proposed and evaluated to represent the P-h curve. One is using 2nd order polynomial trendline approach, the other is to use the forces at different indentation depth. The performance of the ANN based on the trendline approach is evaluated with MSE and relative error of the curve coefficient and the average error in forces over different depths. A frequency method is used to analyse the data, which provided important data/base to further enhanced the accuracy of the P-h curve based on averaging multiple ANN tests. This approach effectively taking use of the fact that ANN prediction is not continuous around any property point. The ANN program with the depth based approach showed similar accuracy in predicting P-h curves of hyperfoam materials. The program was validated in blind tests with numerical data and experimental data on two EVA foams with known properties. Comparison with other approaches (including surface mapping and direct date space fitting process) showed that the ANN program is accurate and much quicker than some other approaches and direct FE modeling. The feasibility of using ANN to directly predict the material properties is evaluated including assessing its capacity to predict trained data and untrained data. The use of single indenter approach and dual indenter approach is assessed. It was found that the approach with 2nd order polynomial fitting of the P-h curves is not able to predict the material parameters. Using 3rd order fitting showed much improvement and it is able to predict the trained data accurately but could not be used to predict untrained data. Works on dual indenter approach with R4 and R6 showed some improvement in predicting untrained data but could not produce data with reasonable accuracy of the full dataset. A new approach utilising the direct ANN program for P-h curve prediction is developed. A computerised program (with Web based interface) has been developed including data generation through ANN, data storage, interface for input and viewing results. A searching program is developed which enables the identification of any possible materials property sets that produce P-h curves matching the experiment data within a predefined error range. The approach is applied to analysis single and dual indenter methods through blind tests with model materials (with known material properties). A new approach using foams of different thickness is also proposed. The results showed that in a single indenter approach, there are multiple materials property sets that can produce similar P-h curves, thus the results are not unique. Dual indenter size approach showed a significant improvement in mapping out all potential material sets matching the tetsign data. The new program successfully identify addition material property sets that can produce P-h curve that match both R4 and R6 data, which was not identified previously with other inverse programs. The new approach proposed of using the tested data on samples of different thickness showed that the uniqueness of the prediction can be improved. The accuracy and validity of the program is firstly assessed with blind tests (using numerical data as input/target) then used to predict the properties of the EVA foam samples. Some key results of the real foam data is compared to the target and prediction results from other programs and data processing method, the comparison results showed that the new ANN base computer program has clear improvement in accuracy, robustness and efficiency in predicting the parameters of EVA foams. Future work is to transfer the program and methodology developed to other material system and testing conditions and further develop the computer program for material developments and research.

This thesis has focused primarily on the effect of bond and workpiece composition on the performance of vitreous-bonded alumina grinding wheels. The effect of bond composition considered in this work can equally be applied to grinding wheels which use silicon carbide (carborundum) as the abrasive medium. The bonds considered in this study are described as sintering bonds (high clay content), used in silicon carbide grinding wheels, - and fusible bonds (high glass content), used in vitreous bonding systems suitable for use in aluminium oxide grinding wheels. The initial part of the research work deals with a review of the mechanisms of grinding and the evaluation of wheel performance. The effect of grinding conditions, abrasive compositions, and workpiece material composition on the mechanisms of grinding wheel wear in conventional wheels was studied. The analysis of grinding wheel wear was examined and compared with experimental data. Reactions in grinding wheel bond materials were examined by comparing theoretical equilibrium compositions with actual reaction products using experimental techniques such as x-ray powder methods and differential thermal analysis. Experimental studies were carried out to investigate the vitrification behaviour of sintering and fusible bonds. This was achieved by examining the relationship between theoretical equilibrium liquid and silica contents and experimental vitrification conditions. A semi-empirical model was developed for determining optimum firing conditions for sintering and fusible bonds. The effect of bond composition on the strength of sintering and fusible bonds, under fixed firing conditions, was investigated. This resulted in some bonds failing by cracks around quartz particles, whilst bonds with high glass contents failed by a combination of pore-flaws. A model was also developed which predicted the amount of quartz remaining after heat treatment. The model was shown to be accurate when compared with experimental data. Based on the results of the experimental work on bond characterisation, the effect of bond and workpiece composition was compared with grinding wheel performance data. This was achieved by grinding a variety of hardened tool steels with abrasive segments manufactured with optimised grades. An empirical model was developed which showed that wheel wear was a function of bond strength and the nature of complex carbides present in the microstructure of the tool steels.

Fringe projection is an optical technique for three dimensional non-contact measurement of height distributions. A fringe pattern is projected onto an object's surface and, when viewed off-axis, it deforms to follow the shape of the object. The deformed fringe pattern is analysed to obtain its phase, information that is directly related to the height distribution of the surface by a proportionality constant. This thesis analyses some key problems in fringe projection analysis. Special attention is focused on the automatisation of the process with Fourier Fringe Analysis (FFA). Unwrapping, or elimination of 21t discontinuities in a phase map, is treated in detail. Two novel unwrapping techniques are proposed, analysed and demonstrated. A new method to reduce the number of wraps in the resulting phase distribution is developed. A number of problems related to FFA are discussed, and new techniques are presented for their resolution. In particular, a technique with better noise isolation is developed and a method to analyse non-fullfield images based on function mapping is suggested. The use of parallel computation in the context of fringe analysis is considered. The parallelisation of cellular automata in distributed memory machines is discussed and analysed. A comparison between occam 2 and HPF, two compilers based upon a very different philosophy, is given. A case study with implementations in occam 2 and high performance FORTRAN (HPF) is presented. The advantages and disadvantages of each solution are critically assessed.

No description available.

A theoretical model has been developed which can simulate a linebreak occurring in a gas pipeline. By assuming one-dimensional homogeneous gas flow and neglecting minor losses and changes in cross-sectional area of the pipe, three simultaneous non-linear partial differential equations were derived from first principles which mathematically model pressure transients in a non-perfect gas. A constant value steady-flow friction factor was used to calculate the frictional losses which was considered to be a reasonable approach since it would not be possible to account for all the variations in friction. The heat transfer into the pipe was accounted for using a constant value Stanton Number approach which again was an acceptable approximation considering the comparatively small effect that heat transfer has on the pressure transients. The equations were converted to ordinary differential equations using the Method of Characteristics and these were then solved numerically using a Taylor expansion. A novel feature of this project was the incorporation of a reduced grid size in the vicinity of the break allowing closer monitoring of the expansion waves in this area. Also included was a means of modelling flow reversal in the pipe which enabled situations with a non-zero initial flow rate to be simulated. A computer code solving the mathematical model was written in Fortran 77 for use on a Gould PN9005 mainframe computer. Both tabular and graphical output were produced which could then be compared with available experimental data. The experimental data that was selected for validation of the theoretical model included shock tube test results and some full size tests. Reasonable agreement was obtained between the theoretical and experimental results and any possible error sources were investigated.

The European Union (EU) aims to reduce overall carbon dioxide emissions at least 80% by 2050. For road transport, this involves at least a 95% reduction target for 2050, compared to 1990 levels. Most commentators believe that achieving this target requires a transition from internal combustion engine vehicles (ICEVs) to battery electric vehicles (BEVs). However, such transition demands fundamental changes in the whole automotive value chain. This research argues that the required changes in the automotive value chain might be achieved by i) an industrial structure enabling the mass production of BEVs ii) understanding and supporting the development of newcomers that are in the majority of micro, small and medium sized enterprises (SMEs) in emerging BEV sector and iii) use of target instruments by governments to accelerate the development of BEV value chain and industrial structure. Based on this strategy, three stage study was performed. This involved i) exploring the present BEV industry structure and compatible future structure ii) exploring the approach of SMEs to emerging BEV sector to understand and support these actors and iii) developing and trialling a novel framework enabling the pre-implementation analysis of putative policy measures. In each stage of the research, different methodologies were used. This included an analysis of supply chain for BEVs in North-West Europe (NWE); semi-structured in-depth interviews with SMEs throughout NWE and development and application of an “adaptive neuro-fuzzy inference system” (ANFIS) based framework. This study contributes to the body of knowledge by investigating the implications of BEVs on the supply chains and exploring what competences and capacities might be needed for mass production of BEVs in Europe. Secondly, this research proposed that economic growth and emission reduction targets established in the existing economic strategy of the EU (Europe 2020 strategy) might be achieved, and a significant contribution to achieve the 2050 emission reduction target might be made by supporting SME development. Support areas for SMEs were also identified. Lastly, to support national governments in making informed decisions, an ANFIS framework providing an ex-ante impact of various innovation decisions was offered.

Fibrous materials are promising for a wide range of engineering applications due to their low density and high stiffness and strength. Stochastic filamentous networks can be widely found in biomaterials at the micro- and nano-scales. The objective of this study is to investigate the mechanical properties of macro-sized, micro-sized and nano-sized stochastic fibrous networks with cross-linking. A continuum mechanics-based three-dimensional periodic beam model has been developed to describe stochastic fibrous materials by the Finite Element Method (FEM). Relative density is a key parameter to elucidate the mechanical properties of porous fibrous materials. The relative density of the beam model developed in this study can be adjusted by changing the concentration of the cross-linker, the fibre aspect ratio and the coefficient of overlap. In general, the non-dimensional Young’s moduli and shear moduli increase with increasing relative density. The simulation and analytical model have suggested that strut bending is the dominant deformation mechanism for stochastic fibrous materials. Based on the total strain energy density, scalar measures of characteristic stress and strain have been applied to reveal the yielding of stochastic fibrous materials. The effect of relative density on uniaxial yield strength of stochastic fibrous materials shows a quadratic function in the x direction and a cubic function in the z direction. When the dimensions of fibrous structures are reduced to the micro- or nano-scale, the stiffness is much different from that of their macro-sized counterparts. Strain gradient effects at the micro-meter scale, and the surface elasticity and initial stress effects at the nano-meter scale have been incorporated into the deformation mechanism of fibrous materials. For both of the micro- and nano-sized fibrous structure, the smaller the diameter, the larger the non-dimensional Young’s moduli and shear moduli. Generally speaking, the dimensionless stiffness of nano-sized stochastic fibrous structures is larger than their micro-sized counterparts. The size-dependent effects investigated in this study could provide good reference points for scientists in tissue engineering and serve as a guide in the design of MEMS and NEMS.

This thesis presents new insights into gaps in the knowledge of conventional spinning and single point incremental forming (SPIF) processes through numerical modelling of their deformation mechanics. The deformation mechanics of conventional spinning is investigated by constructing finite element (FE) models of a cylindrical cup using both single and dual roller passes. A design of experiments (DOE) technique is used to generate an experimental plan based on all the relevant process parameters, followed by an analysis of variance (ANOVA) approach which is then used to determine the most critical parameters. The results indicated that the area in which most of the plastic deformation is taking place changes during the subsequent passes. The deformation mechanics of SPIF is investigated by constructing a novel dual-level finite element model of the forming of a truncated cone. The first-level FE model is validated against experimental data and the second level FE model is used to investigate the deformation modes through the sheet thickness. DOE and ANOVA techniques are used to investigate the influence of the different process parameters on the predicted through-thickness shear. Simple strategies are applied to reduce the geometrical errors without affecting the process flexibility. The results of the second-level FE model indicated that through-thickness shear is an important component in the deformation mechanism in SPIF.

This thesis is about how a vehicle can, without human intervention, be navigated and guided in its movements through its environment. To move a real mobile robot so that it traces out a desired path, 'commands' need to be dispensed to the control systems of the actuators that drive the wheels that move the vehicle. Algorithms which issue such commands are called guidance algorithms. These can cause the vehicle to move about at the desired speed, in the desired direction, and can change the direction of motion, or can achieve some other 'complex' manoeuvre. As commands from guidance algorithms are physically realised, and become the sensible motion of the mobile robot, the desired 'intentions' embodied in them become corrupted. To combat this corruption the mobile robot needs to keep track of where it is in relation to some reference system. This is navigation. The mobile robot needs to navigate so that 'commands' to the actuation systems can then be reformulated in terms of its navigated 'location', given the task it is doing, and where it has been commanded to go to. In this thesis three navigational phases are distinguished for a wheeled 'robotic' vehicle. Their utility was tested and confirmed by experiment, using a 0.5 tonne mobile robot equipped with the relevant sensors, and actuation systems. The three phases of navigation are:- 1) Deduced reckoning based on the intrinsic motion of the vehicle to produce an initial estimate of the vehicle's position and heading. 2) The use of an absolute measurement of the vehicle's bearing to correct errors in the estimated heading. 3) The use of sonar range measurements to objects in the surroundings to correct errors in the estimated position. The positional coordinates, orientation, and extent of these objects being held in a 'world map'. Two guidance algorithms to control a mobile robot's movement are needed, correctly sequenced and coordinated, to enable it to perform a range of useful activities. This thesis has examined 1) Guidance to achieve motion with zero curvature, for a specified distance, and orientated relative to some specified direction in the environment. 2) Guidance to achieve the reorientation of a vehicle, that has to move in order to turn, so that it can move forward again with zero curvature in a different direction. Finally, a new technique that modulates the steering wheel angle with a time dependent Gaussian envelope is given. This technique is able to produce desirable changes in the position and heading of a path curvature limited vehicle, as it moves. Examples of manoeuvres possible with this technique are illustrated.

The work described In this then is was initiated in response to motivation from the needs of industry, the desire to investigate the performance of a process control computer in a relatively novel application as well as to provide training in methods of research. Ever-increasing labour costs have caused the automotive and petroleum industries to seek new means of maintaining the throughput of engine testing work. Their task has been made more difficult by the stringent test regulations that have been introduced with the very commendable intention of reducing atmospheric pollution. In consequence, any means by which the efficiency of testing could be improved and the throughput of work increased were deemed worthy of investigation. Engine testing involves a diversity of simple repetitive operations. These include the collection and processing of data and the execution of logical operations. The digital computer has proved itself to be ideally suited to performing such tasks, but the problem of integrating a computer with such an activity remains only partially solved. It is hoped that the work described in this thesis will go some way towards solving this problem. A description of the instrumentation and interfacing used on the test rig is included together with a description of the program structure and functions. These are not regarded as exemplary but it is hoped that they will aid the identification of the requirements for similar systems. A linearised mathematical model is developed to represent both the static and dynamic behaviour of the engine and dynamometer. This aspect of the study has provided useful insight into the problems associated with the control of engine test rigs. As a result it has been shown that effective control can be made available without recourse to highly sophisticated techniques. Optimisation systems as applied to the control of spark timing and mixture strength are considered. The limitations imposed on their operation by the inherent nature of combustion are outlined. Finally some computer controlled tests that were implemented are described as a means of illustrating the very extensive capabilities of such a system.