Masters Degrees (Mechanical Engineering)

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An automated apparatus for non-contact inspecting of mass produced custom products.
(2009) Davrajh, Shaniel.; Bright, Glen.
The evolution of the manufacturing industry may be viewed as proceeding from Dedicated Manufacturing Systems (DMS) to Reconfigurable Manufacturing Systems (RMS). Customer requirements change unpredictably, and so DMS are no longer able to meet modern manufacturing requirements. RMS are designed with the focus of providing rapid response to a change in product design, within specified part families. The movement from DMS to RMS facilitates mass-production of custom products. Custom parts require inspection routines that can facilitate variations in product parameters such as dimensions, shape, and throughputs. Quality control and part inspection are key processes in the lifecycle of a product. These processes are able to verify product quality; and can provide essential feedback for enhancing other processes. Mass-producing custom parts requires more complex and frequent quality control and inspection routines, than were implemented previously. Complex, and higher frequencies of inspection negatively impact inspection times, and inherently, production rates. For manufacturers to successfully mass-produce custom parts, processes which can perform complex and varying quality control operations need to be employed. Furthermore, such processes should perform inspections without significantly impacting production rates. A method of reducing the impact of high frequency inspection of customized parts on production rates is needed. This dissertation focuses on the research, design, construction, assembly, and testing of a Non- Contact Automated Inspection System (NCAIS). The NCAIS was focused on performing quality control operations whilst maintaining the maximum production rate of a particular Computer Integrated Manufacturing (CIM) cell. The CIM cell formed part of a research project in the School of Mechanical Engineering, University of KwaZulu-Natal; and was used to simulate mass-production of custom parts. Two methods of maintaining the maximum production rate were explored. The first method was the automated visual inspection of moving custom parts. The second method was to inspect only specified Regions of Interest (ROIs). Mechatronic engineering principles were used to integrate sensor articulation, image acquisition, and image processing systems. A specified maximum production rate was maintained during inspection, without stoppage of parts along the production line occurring. The results obtained may be expanded to specific manufacturing industries.
Sensor based real-time mechatronic control of computer integrated manufacturing
(2008) Kumile, Christopher Matlalo
Industrial competition is characterised by increasing globalisation of markets, coupled with
Design of an autonomous underwater vehicle : vehicle tracking and position control.
(2010) Holtzhausen, Servaas.; Bright, Glen.
This project proposes the development of an autonomous underwater vehicle that can be used to perform underwater research missions..The vehicle can be pre-programmed to complete a specified mission. Missions may include underwater pipe inspection, a survey of the sea floor or just the transport of given sensors to a certain depth or position and take measurements of underwater conditions. The Mechatronics and Micro Manufacturing group at the CSIR is engaged in developing a portfolio of autonomous vehicles as well as fur- ther research into the development and implementation of such vehicles. Underwater vehicles will form part of the portfolio of autonomous vehicle research. Autonomous underwater vehicles (AUVs) are mostly used for research purposes in oceanographic studies as well as climate studies. These scientists use AUVs to carry a payload of sensors to specified depths and take measurements of underwater conditions, such as water temperature, water salinity or carbon levels as carbon is being released by plankton or other ocean organisms. Very little information is available about what is happening below the surface of the oceans and AUVs are being used to investigate this relatively unknown environment. The area covered by the world's ocean is 361 million km2 with an average depth of 3790 m. The deepest surveyed depth point in the ocean is at a depth of about 11 000 m at the southern end of the Mariana Trench in the Pacific Ocean. This just shows the need for research into this mostly unexplored world. Research and exploration in the oceans can be achieved through the use of autonomous underwater vehicles. A big problem to overcome is the fact that GPS is not available for navigation in an underwater environment. Other sensors need to be found to be used for navigational purposes. The particular vehicle developed for this study will be used to facili- tate further research into underwater vehicle navigation and underwater robotics.
Performance based analysis of current South African semi trailer and b-double trailer designs
(2010-08-31) Thorogood, Rhys L.
South African heavy vehicles are currently designed according to prescriptive standards designed and enforced by the National Department of Transport (DoT); these standards are regulated in terms of mass, dimensions and vehicle configuration. However, the current prescriptive standards leave little room for innovation in terms of heavy vehicle design. Performance Based Standards, or PBS, is a new Australian based innovative alternative to the current heavy vehicle prescriptive standards, mass, dimensions and vehicle configuration. PBS seeks to align actual vehicle performance efficiencies, productivity and safety objectives as well as road and bridge infrastructure to the current road network. Vehicle performance measures are based on engineering and science, supporting superior safety and known road and bridge wear performance criteria. PBS produces “a result orientated approach” to improved heavy vehicle operations and safety rather than a „one size fits all approach‟ utilised by the current prescriptive legislation. Currently, dynamic vehicle simulations are not carried out on South African manufactured vehicle combinations. Evidence exists that this has, in some cases, resulted in safety compromises. The computer dynamic vehicle simulation technology developed and validated could be employed for the credible assessments of the vehicle design concepts/prototypes for compliance with PBS. This service, which includes vehicle performance simulation and testing, development of high productivity vehicle concepts, assessment and development of risk management strategies, advice on safety and productivity issues, would have a substantial commercialisation potential for the implementation in the larger transport industry in South Africa.
A study and implementation analysis of an anti-sagging device for power transmission lines using shape memory alloys
(2010-08-31) Lüssi, Kevin M.
Shape memory alloys (SMA’s) are a family of metals that exhibit properties of pseudo-elasticity
Numerical simulation of the structural response of a composite rocket nozzle during the ignition transient.
(2009) Pitot de la Beaujardiere, Jean-Francois Philippe.; Bright, Glen.; Morozov, Evgeny.
The following dissertation describes an investigation of the structural response behaviour of a composite solid rocket motor nozzle subjected to thermal and pressure loading during the motor ignition period, derived on the basis of a multidisciplinary numerical simulation approach. To provide quantitative and qualitative context to the results obtained, comparisons were made to the predicted aerothermostructural response of the nozzle over the entire motor burn period. The study considered two nozzle designs – an exploratory nozzle design used to establish the basic simulation methodology, and a prototype nozzle design that was employed as the primary subject for numerical experimentation work. Both designs were developed according to fundamental solid rocket motor nozzle design principles as non-vectoring nozzles for deployment in medium sized solid rocket booster motors. The designs feature extensive use of spatially reinforced carbon-carbon composites for thermostructural components, complemented by carbon-phenolic composites for thermal insulation and steel for the motor attachment substructures. All numerical simulations were conducted using the ADINA multiphysics finite element analysis code with respect to axisymmetric computational domains. Thermal and structural models were developed to simulate the structural response of the exploratory nozzle design in reference to the instantaneous application of pressure and thermal loading conditions derived from literature. Ignition and burn period response results were obtained for both quasi-static and dynamic analysis regimes. For the case of the prototype nozzle design, a flow model was specifically developed to simulate the flow of the exhaust gas stream within the nozzle, for the provision of transient and steady loading data to the associated thermal and structural models. This arrangement allowed for a more realistic representation of the interaction between the fluid, thermal and structural fields concerned. Results were once again obtained for short and long term scenarios with respect to quasi-static and dynamic interpretations. In addition, the aeroelastic interaction occurring between the nozzle and flow field during motor ignition was examined in detail. The results obtained in the present study provided significant indications with respect to a variety of response characteristics associated with the motor ignition period, including the magnitude and distribution of the displacement and stress responses, the importance of inertial effects in response computations, the stress response contributions made by thermal and pressure loading, the effect of loading condition quality, and the bearing of the rate of ignition on the calculated stress response. Through comparisons between the response behaviour predicted during the motor ignition and burn periods, the significance of considering the ignition period as a qualification and optimisation criterion in the design of characteristically similar solid rocket motor nozzles was established.
Performance evaluation of WiMax for rural backhaul.
(2010-10-18) Singh, Verosha.
Technologies such as WiFi and WiMAX, can be a powerful driving force for increasing rural
Investigation and development of structural composite materials for use as electromagnetic shielding agents in the current aerospace industry.
(2010-10-20) Maharaj, Denver.
Due to the nature of today's competitive electronics market, the development of new electronic
Parallel robot design incorporating a direct end effector sensing system.
(2007) Shaik, Ahmed Asif.; Bright, Glen.
This dissertation details the development of a parallel robot with an integrated direct end effector sensing system, from concept to prototype model and includes details of research, design, simulation, construction, assembly and testing. Current research in parallel robots is insufficient as compared to serial type machines, even though their existence has been known for some time. The reasons are the difficulty in conceptualising unique parallel mechanisms, achieving machines that are capable of high accuracy, solving their complex kinematics, dynamics and control problems. There are many advantages of parallel machines that rival the serial type, and these warrant further studies. The second aspect of this project was the design of a direct end effector sensor system. Many existing automated multi-axis machines operate under overall 'open loop' control. The exact position in space of the end effector or tool head, for those machines, is not sensed directly but is calculated by software monitoring sensors on actuator axes. This sensor system and robot structure was designed specifically for use in the agricultural and general food processing/packaging industries. The accuracy and repeatability of such a machine and its sensor system are in the millimetre range.
Reconfigurable modular machine design for reconfigurable manufacturing environment.
(2006) Xing, Bo.
Manufacturing techniques are based on the principles of Flexible Manufacturing and
Modelling of carbon nanotubes and carbon nanotube-reinforced polymers with applications to composite structures.
(2010-11-01) Wuite, Justin.
Owing to their exceptional mechanical and physical properties, carbon nanotubes seem to
A mechatronic approach to develop the concept of a materials handling system for a reconfigurable manufacturing environment.
(2010-11-01) Naidu, Priyen.
People are unique and display a variety of preferences with regard to the products that are
The measurement of axial turbine tip clearance flow phenomena in a moving wall annular cascade and in a linear cascade.
(1989) Morphis, George.; Bindon, Jeffrey Peter.
On unshrouded axial flow turbine rotors, the tip clearance, required for thermal expansion and manufacturing limitations, allows fluid to leak from the pressure side to the suction side of the blade. This flow across the blade tip causes a large proportion of the overall rotor loss. In this work, the flow was visualized, microscopic static pressures taken and flow field measurements were done in the blade tip region to investigate the complex nature of tip clearance flows. An annular turbine cascade with a rotating outer casing was used to simulate the relative motion at the tip of an axial rotor. It was found that relative motion did not have a significant effect on the basic structure of the micro-flow, even though it reduced the leakage mass flow rate which is important as far as mixing loss formation is concerned. The existence of a narrow, very low pressure depression, caused by the flow remaining attached around the sharp pressure corner edge, was confirmed. The width and pressure of the separation bubble were found to be strongly dependent on gap size but the relationship was not linear. The point at which the separation bubble reattaches was seen to coincide with a slight rise in static pressure. The separation bubble which caused the majority of the internal gap loss, and which was thought to contribute to the mixing loss, was shown to disappear when the pressure corner was given a radius of 2,5 gap widths.A linear cascade was used to evaluate the performance of two blade tip shapes that substantially reduced internal gap loss and to compare them to a standard sharp or flat tip blade. A method whereby linear cascade data was analyzed as if it were a rotor with work transfer, was used to evaluate the performance of the various blade tip geometries. It was found that both modified tips increased the mixing loss due to the extra leakage mass flow rate. The first tip with the radiused pressure corner was seen to have a lower efficiency than the flat tip blade. A second tip that was contoured to shed flow in a radial direction and thus decrease the leakage mass flow rate through the gap was seen to significantly increase the overall efficiency.
Experimental and numerical study of heat transfer on turbine blades.
(2007) Kennedy, Graham Stuart.
An experimental and numerical study of he aerodynamics and the associated heat transfer on turbine blades, has been carried out as part of the ongoing Armscor Denel aircraft engine maintenance program. The experimental tests were performed using an existing continuous flow cascade test facility at the University of KwaZulu-Natal, Durban. These experimental results were used to validate the two-dimensional numerical results, generated usmg a commercially available Computational Fluid Dynamics (CFD) package, FLUENT. The existing experimental turbine test facility utilises a continuous flow cascade technique where a cooled, instrumented blade is rapidly introduced to the hot-air stream exposing it to the cascade flow. This creates the heat transient required for measurement of the isothermal heat transfer coefficients, using thin-film heat flux gauges. A static pressure test blade is used in conjunction with a scanivalve system, to determine the blade mid-span pressure distribution. This latest research effort requires validation of de Villiers' [2002] results, whilst improving the error discrepancies between the experimental and numerical analyses. Maintenance on the test rig has been performed, including the addition of a new pressure control system to ensure the correct cascade flow conditions and boundary conditions are obtained. Experimental pressure distribution measurements were performed, to validate previous work by de Villiers [2002] and to ensure the correct operation of the test rig. Experimental error was identified in de Villiers' [2002] suction surface pressure distribution, and new experimental pressure results were acquired. Following the essential overhaul of critical rig components, experimental heat transfer tests were performed. The newly restored equipment produced new isothermal heat transfer coefficient results that validated the results of de Villiers' [2002]. Numerous CFD meshing techniques were investigated and implemented in FLUENT, to produce the numerical solution. The pressure correlation proved to be excellent with an average error of 3%. The varying cascade inlet turbulence intensity was identified as a major source of heat transfer error. Implementing this variance into FLUENT, a significant reduction in error was seen. The resulting average heat transfer error measured 12%, a major improvement from 29% error in 2002.
An experimental and numerical convective heat transfer analysis over a transonic gas turbine rotor blade.
(2006) Cassie, Keith Baharath.; Govender, Saneshan.
An experimental and numerical investigation of the flow and convective heat transfer distribution around a high turning angle gas turbine rotor blade has been carried out at the University of Kwa-Zulu, Durban campus. This study in gas turbine blade aerothermodynamics was done to meet the research and development requirements of the CSIR and ARMSCOR. The experimental results were generated using an existing continuously running supersonic cascade facility which offers realistic engine conditions at low operating costs. These results were then used to develop and validate a 2-D model created using the commercially available Computational Fluid Dynamics (CFD) software package, FLUENT. An initial phase of the study entailed a restoration of what was an unoperational experimental facility to a state capable of producing test simulation conditions. In the analysis, a 4-blade cascade system with provisions for an interchangeable, test blade was subjected to the steady state conditions set up by the facility. Firstly, the flow was characterised by evaluating the static pressures around the midspan of a pressure measurement test blade. This was done using two pressure transducers, a scanivalve, an upgraded data acquisition system and LABview software. The method for measuring the heat transfer distributions made use of a transient measuring technique, whereby a pre-chilled Macor test blade, instrumented with thin film heat flux gauges was rapidly introduced into the hot cascade flow conditions by displacing an aluminum dummy blade while still maintaining the flow conditions. Measurement of the heat flux and generation of the isothermal heat transfer co-efficient distributions entailed re-instrumentation of the test blade section with gauges of increased temperature sensitivity along with modifications of the associated electrical circuitry to improve on the quality of experimental data. Both the experimental flow and heat transfer data were used to validate the CFD model developed in FLUENT. An investigation into different meshing strategies and turbulence models placed emphasis on the choice of model upon correlation. The outcome of which showed the k -co model's superiority in predicting the flow at transonic conditions. A feasibility study regarding a new means of implementing a film cooled turbine test blade at the supersonic cascade facility was also successfully investigated. The study comprised of experimental facility modifications as well as cascade and blade redesigns, all of which were to account for the requirements of film cooling. The implementation of this project, however, demanded the resources of both time and money of which neither commodity was available.
The formulation of process variables for the elimination of defects in a semi-solid high pressure die cast component.
(2006) Reinhardt, Carl Jurgen.; Verijenko, Belinda-Lee.
Semi-Solid Metal (SSM) forming has distinct advantages: strength, near net shape, thick and thin sections and a large scope of materials able to be cast. The aim of this project is to produce a near net shape component using SSM casting with A356 primary Semi Solid Aluminum feed stock from SAG. The selected Short Arm Component was identified as a suitable component for SSM forming, it is used as part of an insulated securing mechanism in overhead pylons, demands high strength and has relatively thick sections. A combination of full and short shot castings from the component and modular die were produced, on the real time shot controlled 62.5 ton high pressure die casting machine, at varying casting parameters of die temperature between 140-250°C, gate velocities of between 1.01-2.87ms_1 and a billet temperature of between 578-582°C. To understand fluid flow and locate possible defects, X-ray radiography and naked eye surface observations of the castings were used to locate possible defects and irregularities, which were cross sectioned and analysed using a Scanning Electron Microscope with an Energy Dispersion Spectroscopy module. It was apparent from the current project, as well as from literature, that increases in the die cross-sectional area reduce the shear surface area and increase the viscosity causing undesirable mould filling behaviour.
Heat transfer enhancement in nano-fluids suspensions : thermal wave effects and hyperbolic heat conduction.
(2005) Vadasz, Johnathan John.; Govender, Saneshan.
The spectacular heat transfer enhancement revealed experimentally in nanofluids suspensions is being investigated theoretically at the macro-scale level aiming at explaining the possible mechanisms that lead to such impressive experimental results. In particular, the possibility that thermal wave effects via hyperbolic heat conduction could have been the source of the excessively improved effective thermal conductivity of the suspension is shown to provide a viable explanation although the investigation of alternative possibilities is needed prior to reaching an ultimate conclusion.
Thermal shock and thermal stress prediction on a highly loaded turbine nozzle guide vane based on an aerodynamic and thermal analysis.
(2005) Kulik, Krzysztof.; Govender, Saneshan.
A 2-D plain strain CFD/FEM model to simulate thermal shocks and stresses in a turbine blade has been set up using the commercially available software FLUENT and NASTRAN. The model was validated against the experimental data of Bohn et. al. and used to simulate real test cases. The steady state numerical model was set up for a single Mark II nozzle guide vane using the correct boundary conditions to resolve the flow field. A combined laminar and turbulent model was developed in FLUENT that was used to highly accurately predict the pressure, temperature and heat transfer coefficient distribution on the blade surface as well as the temperature distribution on the cooling holes inside the blade. The resulting temperature profiles on the blade and cooling holes were used as boundary conditions for the FEM analysis to resolve the internal temperature and stress profiles. The pressure, temperature and heat transfer distribution on the blade, from FLUENT, were compared to those from Bohn et. al. The predicted pressure distribution was exact with the experimental results and the predicted temperature distribution had an average overprediction of 1.4 % on both the pressure and suction side. The internal temperature profile predicted by NASTRAN was correctly predicted with an average over-prediction of 2 %. The stress contours were accurately predicted with the stress magnitude varying by 17 % to that of Bohn et. al. The reason for the difference between the MSC.NASTRAN and Bohn et. al. stress results is believed to be purely solver related. Bohn et al. used a FEM package called MSC.MARClMentat. With the steady state model validated, transient test cases were simulated that represent typical operational data. The mission profile was obtained for the T-56 engine found on the C130 cargo plane. The model was used to simulate the test case where the turbine inlet temperature (TIT) varied with time. The simulation results showed that stress was proportional to TIT, where changes in the TIT were seen later in the stress curve, due to conduction in the blade. Steep TIT changes, such as shock loads affected stress later than gentler TIT changes. Thus, the FLUENT / NASTRAN model was successfully validated, and used to simulate a flight mission profile. The goal to calculate quality unsteady stress profiles was achieved and forms the boundary conditions for thermal fatigue calculations.
The development of a catchment scale irrigation systems model for sugarcane.
(2005) Moult, Nicholas Greig.; Smithers, Jeffrey Colin.
The implementation of the National Water Act (1998) requires significant changes in the institutional arrangements for water management and, to cater for human and environmental needs, as well as addressing historical inequities, water allocations to irrigated agriculture are likely to be affected. As a result, farmers are facing increasing pressure to use water more effectively, to justify existing water requirements and to budget and plan with growing uncertainty regarding water availability. Therefore, a tool to manage and assess catchment water supply and demand interactions and the associated impacts on the profitability of irrigated sugarcane would be of great value. Although there have been several independent model developments in the fields of water management and sugarcane growth, none provide the required management information in an integrated manner. However, these models provide the foundation for the development of the required modelling tool. An irrigation model for sugarcane, ACRUCane, was developed and incorporated into the ACRU2000 modelling system. The water budget simulated by ACRUCane is linked to a surrounding catchment, the hydrology of which is simulated by the ACRU model. In doing so, a tool has been developed that has the capacity to: • model the soil water balance at a field scale for irrigated areas and at a catchment scale for non-irrigated areas, • link an accurate estimation of crop water requirement for an irrigated area with the availability ofwater at a catchment scale, • explicitly account for the impact of the performance of different irrigation systems on the hydrology and, ultimately, on the sugarcane yield of an irrigated area, • assess the impact of different supply constraints on sugarcane yield, and • estimate both sugarcane and sucrose yield. Extensive verification of the model has been undertaken using data from an irrigation trial at La Mercy, South Africa and two separate trials conducted in the Lowveld of Zimbabwe, with the primary objective of the verification studies being to assess the model's ability to account for different scheduling strategies on sugarcane and sucrose yield. The results obtained show that the model accurately captured the relative differences in yield associated with different irrigation treatments and can thus be used evaluate the impact of different scheduling strategies. A case study was conducted where the feasibility of several hypothetical irrigation scenarios were compared. Different scenarios were created by varying application uniformity, scheduling strategies and system type. This case study illustrated how ACRUCane can be used to provide reliable decision support information to irrigators.
Virtual prototyping of an articulated dump truck.
(2003) Govender, Deena.; Kaczmarczyk, Stefan.
In the modem automotive industry product times to market are being increasingly compressed. In the earthmoving and construction machine industry this is also true with the manufacturer having to respond to new customer requirements quickly and decisively. Virtual prototyping is a vital tool in the vehicle engineer's armoury, allowing a large portion of developmental investigation to be done on the virtual model with the attendant savings in time and cost and allowing often dangerous manoeuvres to be predicted and investigated prior to actual physical prototype testing. The University of Natal BELL Equipment collaborative effort involves the vehicle dynamics modelling and model validation of a BELL Equipment manufactured B40C Articulated Dump Truck (ADT). The modelling was completed using the multibody system (MBS) simulation software package, ADAMS. Initial modelling and simulation results are presented with specific attention paid to the introduction of valid data for compliant joints in the MBS as well as modelling of the tire. The physical testing of the ADT is also presented as well as a discussion of the data acquisition system. Key results from the physical testing of the ADT are also presented and discussed.

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