The present study involves the analysis and design optimisation of composite structures using analytical and numerical methods. Five different problems are considered. The first problem considers the design of laminated plates subject to non-uniform temperature distributions. The plates are optimised for maximum buckling temperature using the fibre angle as the optimising variable. The method of solution involves the finite element method based on Mindlin theory for thin laminated plates and shells, and numerical optimisation. A computational approach is developed which involves successive stages of solution for temperature distribution, buckling temperature and optimal fibre angle. Three different temperature loadings are considered and various combinations of simply supported and clamped boundary conditions are studied. The effect of plate aspect ratio on the optimal fibre angle and the maximum buckling temperature is investigated. The influence of bending-twisting coupling on the optimum design is studied by considering plates with increasing number of layers. The second problem concerns the optimal design of composite pressure vessels. Finite element solutions are presented for the design of hemispherically and flat capped symmetrically laminated pressure vessels subjected to external pressure. The effect of vessel length, radius and wall thickness, as well as bending-twisting coupling and hybridisation on the optimal ply angle and buckling pressure are numerically studied. Comparisons of the optimal fibre angles and maximum buckling pressures for various vessel geometries are made with those for hybrid pressure vessels. In the third problem, the multiobjective design of a symmetrically laminated shell is obtained with the objectives defined as the maximisation of the axial and torsional buckling loads. The ply angle is taken as the optimising variable and the performance index is formulated as the weighted sum of individual objectives in order to obtain Pareto optimal solutions of the design problem. Single objective design results are obtained and compared with the multiobjective design. The effect of weighting factors on the optimal design is investigated. Results are given illustrating the dependence of the optimal fibre angle and performance index on the cylinder length, radius and wall thickness. In the fourth problem, the optimal layup with least weight or cost for a symmetrically laminated plate subject to a buckling load is determined using a hybrid composite construction. A hybrid construction provides further tailoring capabilities and can meet the weight, cost and strength constraints while a non-hybrid construction may fail to satisfy the design requirements. The objective of the optimisation is to minimise either the weight or cost of the plate using the ply angles, layer thicknesses and material combinations as design variables. As the optimisation problem contains a large number of continuous (ply angles and thicknesses) and discrete (material combinations) design variables, a sequential solution procedure is devised in which the optimal variables are computed in different stages. The proposed design method is illustrated using graphite, kevlar and glass epoxy combinations and the efficiency of the hybrid designs over the non-hybrid ones are computed. Finally, the minimum deflection and weight designs of laminated composite plates are given in the fifth and last problem. The finite element method is used in conjunction with optimisation routines in order to obtain the optimal designs, as was the procedure in the first problem. Various boundary conditions are considered and results are given for varying aspect ratios and for different loading types. / Thesis (Ph.D.)-University of Natal, Durban, 1996.

Industrial robot arms are an essential part of automated manufacturing, and perform tasks such as component assembly, welding, light machining, spray painting, etc. They are highly repeatable, can be calibrated to be sufficiently accurate and they eliminate human error. The serial robot architecture is by far the most ubiquitous in modern day manufacturing, as the technology is highly refined in its current state; the machine architecture provides great dexterity and it has a large useful workspace. This architecture however does have some problems, one of which is a large machine moving mass. The primary reason for this lies in the location of its motors and gearboxes. Due to the robot's significant inertia it utilizes a large amount of energy. This thesis focused on the mechanical design, mathematical modelling and simulation of 2 robotic arm designs which had a hybrid nature. They were classified as hybrid due to the fact that their architectures departed from both the classic definitions of serial kinematics manipulators/machines (SKMs) and parallel kinematics manipulators/machines (PKMs). The primary design goal was to merge some of the advantages of both architectures, i.e. a large workspace to footprint ratio and high end-effector dexterity which was found in serial robots, combined with the low inertia of a parallel robot for improved dynamics. Serial and parallel robots were complementary, and these design goals could not co-exist in a single purist robot architecture. The designs had a full complement of 6 DOFs (degrees of freedom), 3 DOFs for spatial position of the wrist and 3 DOFs for orientation of that wrist. They also had a lower machine moving mass, a fact that was thought to improve speed and energy usage. A major contribution of this research PhD project was a comparative energy usage study, which was performed against the serial robot as a measure. This was done for both hybrid designs as well as another model which represented 2 existing patented designs. The purpose of that was to determine if lowering the machine moving mass would improve energy efficiency, and to determine which design was best. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.

There were two main objectives for this research. The first objective was to understand how organisations think strategically and formulate strategy for the current and future environments in which they operate, and the second objective was to determine what the organisations were doing to manage complexity and uncertainty in these environments. This necessitated a review of "traditional" or "rationalist" strategy, the "resource based view" of strategy, and if and how organisations use scenario planning as a means to reduce environmental uncertainty, develop strategic options, improve the quality of strategic decisions, and facilitate organisational learning. The methodology followed for the research was qualitative in nature and involved a literature review and three case studies of organisations in two industries. Primary data was acquired from semi structured interviews and workshops, and secondary data came from annual reports, analysts reports, books, journals and periodicals, and documents made available by the subjects of the study. The workshops were also used to confirm the veracity of data and explore emerging information, themes and concepts. The research led to the development of a framework for the analysis of strategy formulation in organisations, and it surfaced three predominant themes: 1. The strategy process and strategic response of organisations will develop in accordance with its market dynamics and environmental drivers. The primary drivers shaping the strategy process and strategic response is the nature of demand in the market and the market context. Secondary drivers are the political, economic, social, technological and regulatory environments. 2. The market context is determined by the industry structure, which can be monopolistic, oligopolistic or open and competitive, and the profile and characteristics of the competition. 3. There are three organisational determinants of the strategic response: the political and cultural systems metaphors, the mental models that develop as a result of these systems, and the type and nature of individual and organisational leaming. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

People are unique and display a variety of preferences with regard to the products that are / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2007.

The concept of mass producing custom products, though extremely beneficial to the commercial, and retail industries, does come with some limitations. One of these is the occurrence of bottlenecks in the materials handling systems associated with reconfigurable manufacturing systems tasked with achieving the goal of mass customisation manufacturing. This specific problem requires the development of an intervention system for rerouting parts and materials waiting in line, around bottlenecks and/or work flow disruptions, to alternative destinations. Mobile robots can be used for the resolution of bottlenecks, and similar disruptions in work flow, in these situations. Embedding autonomy into mobile robots in a manufacturing environment, releases the higher level production management systems from routing of parts and materials. The principle of the inverted pendulum has recently become popular in mobile robotics applications, and is being implemented in research projects around the world. The use of this principle produces a two-wheeled mobile robot that is able to actively stabilise itself while in operation. The dissertation is focused on the research, design, assembly, testing and validation of a two-wheeled autonomous materials handling robot for application in reconfigurable manufacturing systems. This robot should be dynamically or statically stable during different phases of operation. The mechatronic engineering approach of system integration has been used in this project in order to produce a more reliable robotic system. The application of the inverted pendulum principle requires that a suitable control strategy be formulated. It also necessetates the ues of sensors to track the state of the robot. Control engineering theory was used to develop an optimal control strategy that is robust enough to cope with varying payload characteristics. The Kalman filter is employed as state estimation measure to improve sensor data. For a mobile robot to be deemed autonomous, one of the requirements is that the robot should be able to navigate through its environment without colliding with obstacles in its path, and without human intervention. A navigation system has been designed, through field specific research, to enable this. The robot is also required to communicate with remote computers housing production management systems as well as with mobile robots that form part of the same materials handling system. Performance analysis and testing proves the feasibility of a mobile robot system. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

The purpose of this research is to make an investigation into the crashworthiness modelling of Sheet Moulding Compound (SMC) composite materials, and to study the response of SMC composite structures under dynamic loading. The primary research objectives are thus to review classical and advanced material failure models, and to perform numerical simulation of the crash of composite structures using already available material models. Additionally, a new material model is to be developed for implementation into a commercially available finite element package. In parallel with the numerical simulation of the crasrung of an SMC composite structure, experimentation is performed which is used as a source of validation and comparison with the simulation. For this purpose a testing regime is introduced, which may be mirrored in simulation. As any material model requires initial experimental inputs, the purpose of experimentation is twofold, with testing required both for the quantification of the required model inputs and the basic material characterisation before simulation may begin, as well as for the proposed validation and comparison after the simulation has been carried out. Thus the design of the testing methodology, as well as the design, selection and fabrication of the testing equipment and the composite specimens and demonstrators, as well the actual testing itself, are necessary secondary requirements of the project. Once the testing regime has been facilitated and carried out, numerical simulation validation using already available composite material models may then be carried out at various levels. The results are then analysed and validated with the resultant justification of a new model being developed. The critical viewpoint to be delivered throughout is the need for theoretical formulations for material modelling to be extensively researched and validated in terms of their implementabilty and practicality, a key analysis seemingly missing in most technical write-ups. Such analyses are performed and discussed here, rughlighting the volume of additional work that is encompassed by such a study. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

The following report investigates district cooling systems. This form of technology provides an alternative means of providing cooling. In a traditional cooling system each building would include cooling equipment to serve only that building. District cooling differs in that water is chilled at one location and pumped to two or more buildings. District cooling has many benefits over traditional cooling systems. This report, however, aims to determine the economic benefits (if any) of district cooling systems. The location chosen as a model for this study was the University of Natal (Durban) campus. This campus currently operates a district cooling system serving six buildings. This study is hypothetical in nature, as the cooling system is already finalized and operational. The aim of this dissertation is to answer the question of which would be the more attractive alternative if the University were in a position of having to install a completely cooling system. One of the most important steps in this process is the calculation of cooling loads. The cooling load was estimated for each of the buildings associated with the district cooling system. The LOADEST software package was used to derive these cooling loads. The accuracy of LOADEST software was also validated in this study. The bulk of this report is composed of the preliminary work required to obtain capital and operating costs for cooling systems, including validation of cooling load calculation software. It was felt that this prelimiinary work justified inclusion in the final report to provide accurate representation of the steps taken before any economic evaluation could be reached. The capital and operating costs of the district cooling system and a more traditional system were compared. It was found that the district cooling system reduces operating costs significantly, although it's capital cost is higher than the traditional system against which it was compared. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

A 2-D CFD / FEM model to simulate thermal stresses in a turbine blade has been set up using the software FLUENT and FIDAP. The model was validated against the data of Bohn et. al. (1995) and was used to simulate 5 test cases. The numerical model was set up for a single Mark II nozzle guide vane (NGV) and utilised the appropriate boundary conditions for the surrounding flow field. A commercially available software code, FLUENT, was used to resolve the flow field, and heat transfer to the blade. The resulting surface temperature profile was then plotted and used as the boundary conditions in FIDAP (a commercial FEM code) to resolve the temperature and stress profile in the blade. An additional solver within FLUENT essentially superimposes an additional flow field as a result of the NGV vibration in the flow field. The pressure, temperature and heat transfer coefficient distribution, from FLUENT, were compared to those from Bohn et. al. (1995). The model predicted the distributions trends correctly, with an average over-prediction for temperature, of 10 % on the suction side and 6 % on the pressure side. This was restricted to the region from leading edge to 40 % chord on both sides of the blade. The blade temperature and equivalent stress contour trends were also correctly predicted by FIDAP. The blade temperature was over-predicted by and average of 1.7 %, while the equivalent stress magnitude was under-predicted by a worst case of 43 %, but the locations of maximum stress were correctly predicted. The reason for the differences between the stresses predicted by FLUENT / FIDAP and the data given in Bohn et. al. (1995), is believed to be the results of the temperature dependence of the material properties for the blade (ASTM 310 stainless steel), used in the two studies, not being identical. The reasoning behind this argument is because the distribution trends and contour variation, predicted by the model, compared favourably with the data of Bohn et. aI., and only the equivalent stress magnitude differed significantly. This completed the validation of the FLUENT / FIDAP model. The model was used to simulate test cases where temperature (i.e. turbine inlet temperature or TIT), at the model inlet (Le. the pressure inlet boundary in FLUENT), was set up to be time varying. Four simplified cases, viz single shock, multiple shocks, simplified cycle and multiple cycles, and a complex cycle (a mission profile) were simulated. The mission profile represented typical gas turbine operational data. The simulation results showed that stress was proportional to TIT. Changes in TIT were seen at a later time in the stress curve, due to conduction through the blade. Steep TIT changes, such as the shock loads, affected stress later than gentler TIT changes - the simplified and multiple cycles. These trends were consistently seen in the complex cycle. The maximum equivalent stress was plotted against TIT to try and develop a loose law that gives maximum equivalent stress as a function of TIT. A 4th order polynomial was fitted through the maxima and minima of the maximum equivalent stress plot, which gave the maximum and minimum stress as a function of TIT. This function was used calculate the maximum and minimum and mean equivalent stress using the TIT data for the mission profile. Thus, the FLUENT I FIDAP model was successfully validated, used to simulated the test cases and a law relating the equivalent stress as a function of TIT was developed. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2002.

Mechatronics encompass a holistic approach to the design, development, production, maintenance and disposal of complex engineering systems, products and processes. The control and modelling of the manufacturing process are carried out in a networked environment allowing for realistic real time control and simulation. This is achieved through the declarative definition of Computer Integrated Manufacturing (CIM) components, the standardisation of CIM interfaces and the object-orientated approach to model development and data management. The development ofthe Modular Mechatronic CIM control system is aimed at intelligently scheduling, controlling and monitoring manufacturing processes in realtime over Internet capable networks. Modular Mechatronics is an alternative design approach that requires the decomposition of a project into separate modules, identifiable by their individual mechatronic functionality. Modular Mechatronic control for Internet manufacturing produces an efficient and effective solution for CIM processes. This approach allows a remote user to monitor and control CIM processes in real time over the Internet allow for a supervisory control structure to control and manage these processes. The modular mechatronic design approach has been applied to the development of the CIM Internet control system, to optimise the overall function ofthe CIM system. A flexible, low cost Modular Mechatronic design approach was used to develop the CIM architecture and computer interface network, which served as the backbone of the Modular Mechatronic CIM control system. The modular designed control system was used to control CIM components in real time over the Internet. The Modular Mechatronic building block development allows for future integration of other CIM components. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2002.

This investigation seeks to perform a comparative study between the combined effects of internal pressure and piping loads versus external pressure and piping loads on a pressure vessel. There are currently several well-known and widely-used procedures for predicting the stress situation and the structural stability of pressure vessels under internal pressure when external piping loads (due to thermal expansion, weight, pressure, etc.) are applied at the nozzles. This project familiarises one with several international pressure vessel design Codes and standards, including AS ME (American Society of Mechanical Engineers) pressure vessel code sections and WRC (Welding Research Council) bulletins. It has been found that many vessels are designed to operate under normal or steam-out conditions (in vacuum). The combined effect of the external atmospheric pressure and the piping loads at the nozzle could be catastrophic if not addressed properly - especially when the stability of the structure is a crucial consideration, i.e. when buckling is a concern. The above-mentioned codes and standards do not directly address procedures or provide acceptance criteria for external loads during vacuum conditions. The approach to the study was, firstly, to investigate the effects of internal pressure and piping loads at the shell-to-nozzle junction. Theoretical stresses were compared with Finite Element results generated using the software package MSC PATRAN. Finite Element Methods provide a more realistic approach to the design of pressure vessels as compared to theoretical methods. It was necessary to determine if the theoretical procedures currently used were adequate in predicting the structural situation of a pressure vessel. Secondly, the buckling effects of vessels subjected to external atmospheric pressure and piping loads were also investigated. Buckling of the shell-to-nozzle region was explored with the aid of Finite Element software. The results gained were used to develop appropriate procedures for the design of vessels under external atmospheric pressure and piping loads. The design is such that it indicates if buckling will occur at the shell-to-nozzle junction. These design procedures form the basis for future exploration in this regard. / Thesis (M.Sc.Eng)-University of Natal, Durban, 2003.