Manufacturing challenges for custom made solar vehicles in South Africa
- Janse van Rensburg, P., Hurter, W., Janse van Rensburg, N., Oosthuizen, G.
- Authors: Janse van Rensburg, P. , Hurter, W. , Janse van Rensburg, N. , Oosthuizen, G.
- Date: 2013
- Subjects: Solar powered vehicles
- Type: Article
- Identifier: uj:4916 , http://hdl.handle.net/10210/13016
- Description: Solar challenges are designed to test the reliability and efficiency of solar powered vehicles in endurance races. In the past these manufactured vehicles were technology drivers and led to advances in electric motors and solar cell efficiency. The speed in relation to power consumption is one of the main design considerations, with the only energy source being solar power. In the design and manufacturing of these vehicles a number of requirements need to be met in order to pass the safety standards. The Sasol Solar Challenge (SSC) created an opportunity for South African universities to design and manufacture custom made solar powered vehicles. This paper explores and discusses the challenges for manufacturing solar vehicles in South Africa. Key elements like the communication gap between design and manufacturing, the cost of lightweight solar encapsulation, the shortage of local suppliers and expertise in composite manufacturing are evaluated. These insights can be used as foundation for strategic decisions by future stakeholders.
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- Authors: Janse van Rensburg, P. , Hurter, W. , Janse van Rensburg, N. , Oosthuizen, G.
- Date: 2013
- Subjects: Solar powered vehicles
- Type: Article
- Identifier: uj:4916 , http://hdl.handle.net/10210/13016
- Description: Solar challenges are designed to test the reliability and efficiency of solar powered vehicles in endurance races. In the past these manufactured vehicles were technology drivers and led to advances in electric motors and solar cell efficiency. The speed in relation to power consumption is one of the main design considerations, with the only energy source being solar power. In the design and manufacturing of these vehicles a number of requirements need to be met in order to pass the safety standards. The Sasol Solar Challenge (SSC) created an opportunity for South African universities to design and manufacture custom made solar powered vehicles. This paper explores and discusses the challenges for manufacturing solar vehicles in South Africa. Key elements like the communication gap between design and manufacturing, the cost of lightweight solar encapsulation, the shortage of local suppliers and expertise in composite manufacturing are evaluated. These insights can be used as foundation for strategic decisions by future stakeholders.
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Residual stress depth profiling of commercially pure titanium subjected to high-speed machining using energy dispersive diffraction
- Janse van Rensburg, N., Madyira, D.M., Laubscher, R.F., Oosthuizen, G.A.
- Authors: Janse van Rensburg, N. , Madyira, D.M. , Laubscher, R.F. , Oosthuizen, G.A.
- Date: 2013
- Subjects: Residual stress , Energy dispersive diffraction , Titanium - Mechanical properties
- Type: Article
- Identifier: uj:4948 , http://hdl.handle.net/10210/13048
- Description: Residual stress is well-known to influence the mechanical properties of machined components. The magnitude and distribution of these stresses are critical to determine the component’s life, specifically under fatigue loading. There exists a growing need to better understand the effects of cutting parameters on residual stress and to identify more innovative methods to evaluate residual stress. Titanium has been widely used, but many of the same qualities that enhance titanium’s appeal for most applications also contribute to it being one of the most difficult to machine materials. High-speed cutting experiments were conducted on commercially pure (CP) titanium and the residual stress depth profile was analysed using energy dispersive diffraction (EDDI). The residual stress depth profile of CP Grade 4 titanium was then evaluated. Experimental results show that cutting speed and depth of cut have a significant effect on the residual stress profile. At a low cutting speed, the surface residual stresses are largely compressive, becoming less compressive with an increase in cutting speed. An increase in depth of cut also introduces more compressive residual stresses into the material.
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- Authors: Janse van Rensburg, N. , Madyira, D.M. , Laubscher, R.F. , Oosthuizen, G.A.
- Date: 2013
- Subjects: Residual stress , Energy dispersive diffraction , Titanium - Mechanical properties
- Type: Article
- Identifier: uj:4948 , http://hdl.handle.net/10210/13048
- Description: Residual stress is well-known to influence the mechanical properties of machined components. The magnitude and distribution of these stresses are critical to determine the component’s life, specifically under fatigue loading. There exists a growing need to better understand the effects of cutting parameters on residual stress and to identify more innovative methods to evaluate residual stress. Titanium has been widely used, but many of the same qualities that enhance titanium’s appeal for most applications also contribute to it being one of the most difficult to machine materials. High-speed cutting experiments were conducted on commercially pure (CP) titanium and the residual stress depth profile was analysed using energy dispersive diffraction (EDDI). The residual stress depth profile of CP Grade 4 titanium was then evaluated. Experimental results show that cutting speed and depth of cut have a significant effect on the residual stress profile. At a low cutting speed, the surface residual stresses are largely compressive, becoming less compressive with an increase in cutting speed. An increase in depth of cut also introduces more compressive residual stresses into the material.
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System dynamics simulation for strategic green supply chain management
- Mutingi, M., Mbohwa, Charles, Mhlanga, S., Mapfaira, H.
- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S. , Mapfaira, H.
- Date: 2013
- Subjects: Green supply chain management
- Type: Article
- Identifier: uj:4946 , http://hdl.handle.net/10210/13046
- Description: The design of appropriate green supply chains in the manufacturing sector is a crucial task. The present paper seeks to (i) identify suitable performance measures for green supply chains and to (ii) develop a dynamic simulation model to assist supply chain decision-makers in developing appropriate policies and strategies in green supply chain management. Based on the principles of the system dynamics methodology, causal linkages between internal and external factors affecting the development of green strategies are investigated. Green concepts are used to develop crucial environmental and eco-efficiency performance measures in regards to strategic green supply management. Results from what-if analysis indicate that proper implementation of green strategies produces significant improvements for environmental, economic/financial and operational performance. Further numerical experiments demonstrate that the model can provide sound managerial insights.
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- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S. , Mapfaira, H.
- Date: 2013
- Subjects: Green supply chain management
- Type: Article
- Identifier: uj:4946 , http://hdl.handle.net/10210/13046
- Description: The design of appropriate green supply chains in the manufacturing sector is a crucial task. The present paper seeks to (i) identify suitable performance measures for green supply chains and to (ii) develop a dynamic simulation model to assist supply chain decision-makers in developing appropriate policies and strategies in green supply chain management. Based on the principles of the system dynamics methodology, causal linkages between internal and external factors affecting the development of green strategies are investigated. Green concepts are used to develop crucial environmental and eco-efficiency performance measures in regards to strategic green supply management. Results from what-if analysis indicate that proper implementation of green strategies produces significant improvements for environmental, economic/financial and operational performance. Further numerical experiments demonstrate that the model can provide sound managerial insights.
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Investigating the effects of composite materials in solar cell encapsulation
- Hurter, W., Oosthuizen, G., Janse van Rensburg, N.
- Authors: Hurter, W. , Oosthuizen, G. , Janse van Rensburg, N.
- Date: 2013
- Subjects: Renewable energy resources , Solar energy , Solar cell encapsulation
- Type: Article
- Identifier: uj:4950 , http://hdl.handle.net/10210/13050
- Description: In the past few decades our society’s increasing demands for energy have naturally resulted in increased utilization of renewable resources such as solar energy. Due to this strong demand the solar car endurance race was established to challenge researchers in this field. A competitive vehicle needs around six square meters of solar cells that produce approximately one kilowatt of power. This equates to 514 monocrystalline silicon half cells. The manufacturing challenge is to protect these cells from the terrestrial elements over a prolonged period of time. In this research study a composite encapsulation method was developed for solar cells and tested. Experiments were conducted to assess the processing of composite materials to improve the mechanical strength of the fragile solar cells. The effects of composites on reinforcement, electrical efficiency and thermal efficiency of the photovoltaic (PV) cells were evaluated. Impact testing to simulate a hailstone shows that the fibreglass sandwich panel structure will protect the surface of the cells, whilst reducing their efficiency by less than 5%.
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- Authors: Hurter, W. , Oosthuizen, G. , Janse van Rensburg, N.
- Date: 2013
- Subjects: Renewable energy resources , Solar energy , Solar cell encapsulation
- Type: Article
- Identifier: uj:4950 , http://hdl.handle.net/10210/13050
- Description: In the past few decades our society’s increasing demands for energy have naturally resulted in increased utilization of renewable resources such as solar energy. Due to this strong demand the solar car endurance race was established to challenge researchers in this field. A competitive vehicle needs around six square meters of solar cells that produce approximately one kilowatt of power. This equates to 514 monocrystalline silicon half cells. The manufacturing challenge is to protect these cells from the terrestrial elements over a prolonged period of time. In this research study a composite encapsulation method was developed for solar cells and tested. Experiments were conducted to assess the processing of composite materials to improve the mechanical strength of the fragile solar cells. The effects of composites on reinforcement, electrical efficiency and thermal efficiency of the photovoltaic (PV) cells were evaluated. Impact testing to simulate a hailstone shows that the fibreglass sandwich panel structure will protect the surface of the cells, whilst reducing their efficiency by less than 5%.
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A dynamic simulation of a lean and agile manufacturing system
- Mutingi, M., Mbohwa, Charles, Mhlanga, S.
- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S.
- Date: 2013
- Subjects: Agile manufacturing , Lean thinking , Manufacturing systems
- Type: Article
- Identifier: uj:4947 , http://hdl.handle.net/10210/13047
- Description: The integration of just-in-time and lean principles in agile manufacturing plays an important role in enhancing the operational performance of manufacturing systems. In this paper, we address this issue by (i) building a set of performance criteria for a typical manufacturing system, (ii) developing a system dynamics model for the system, and (iii) performing experimental “what-if” simulation analyses. Using a system dynamics simulation methodology, the impact of the application of lean and just-in-time policies on a traditional inventory-focused manufacturing system is investigated. System dynamics modelling is used to capture the dynamic causal linkages between different components of the manufacturing system. Different scenarios are generated in order to investigate the dynamics of the system under assumed demand scenarios. The results of the simulation study reveal that manufacturing systems can benefit from the introduction of lean and just-in-time principles, depending on the extent to which the necessary structural changes are implemented. The paper concludes by providing useful managerial insights for effective implementation of lean and agile manufacturing concepts.
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- Authors: Mutingi, M. , Mbohwa, Charles , Mhlanga, S.
- Date: 2013
- Subjects: Agile manufacturing , Lean thinking , Manufacturing systems
- Type: Article
- Identifier: uj:4947 , http://hdl.handle.net/10210/13047
- Description: The integration of just-in-time and lean principles in agile manufacturing plays an important role in enhancing the operational performance of manufacturing systems. In this paper, we address this issue by (i) building a set of performance criteria for a typical manufacturing system, (ii) developing a system dynamics model for the system, and (iii) performing experimental “what-if” simulation analyses. Using a system dynamics simulation methodology, the impact of the application of lean and just-in-time policies on a traditional inventory-focused manufacturing system is investigated. System dynamics modelling is used to capture the dynamic causal linkages between different components of the manufacturing system. Different scenarios are generated in order to investigate the dynamics of the system under assumed demand scenarios. The results of the simulation study reveal that manufacturing systems can benefit from the introduction of lean and just-in-time principles, depending on the extent to which the necessary structural changes are implemented. The paper concludes by providing useful managerial insights for effective implementation of lean and agile manufacturing concepts.
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A framework for developing performance measurement systems for “green” supply chain management strategies
- Mutingi, M., Mhlanga, S, Mbohwa, Charles, Mapfaira, H
- Authors: Mutingi, M. , Mhlanga, S , Mbohwa, Charles , Mapfaira, H
- Date: 2013
- Subjects: Performance measurement , Performance management systems , Supply chain management
- Type: Article
- Identifier: uj:6167 , ISBN 978-0-7972-1405-7 , http://hdl.handle.net/10210/13774
- Description: As environmental issues are continually and rapidly emerging as one of the most crucial topics in strategic manufacturing decision making, the formulation of “green” performance management systems is very important. This research seeks to introduce and explore green performance measurement frameworks that exist in various real-world case studies that are found in literature. The study yielded a set of four taxonomic performance measurement systems that are applicable in specific contexts of manufacturing supply chain strategies. Moreover, specific green performance metrics are provided in respect of the identified green manufacturing strategies. Implications of the application of each performance management system on existing manufacturing policies are evaluated, giving practical managerial insights. The study forms an essential framework for the decision maker to rapidly develop a suitable performance system in a green manufacturing environment, within a reasonable time frame.
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- Authors: Mutingi, M. , Mhlanga, S , Mbohwa, Charles , Mapfaira, H
- Date: 2013
- Subjects: Performance measurement , Performance management systems , Supply chain management
- Type: Article
- Identifier: uj:6167 , ISBN 978-0-7972-1405-7 , http://hdl.handle.net/10210/13774
- Description: As environmental issues are continually and rapidly emerging as one of the most crucial topics in strategic manufacturing decision making, the formulation of “green” performance management systems is very important. This research seeks to introduce and explore green performance measurement frameworks that exist in various real-world case studies that are found in literature. The study yielded a set of four taxonomic performance measurement systems that are applicable in specific contexts of manufacturing supply chain strategies. Moreover, specific green performance metrics are provided in respect of the identified green manufacturing strategies. Implications of the application of each performance management system on existing manufacturing policies are evaluated, giving practical managerial insights. The study forms an essential framework for the decision maker to rapidly develop a suitable performance system in a green manufacturing environment, within a reasonable time frame.
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A process planning framework for milling of titanium alloys
- Dimitrov, D., Conradie, P.J.T., Oosthuizen, G.
- Authors: Dimitrov, D. , Conradie, P.J.T. , Oosthuizen, G.
- Date: 2013
- Subjects: Titanium alloys , Milling , High speed cutting , High performance machining
- Type: Article
- Identifier: uj:4949 , http://hdl.handle.net/10210/13049
- Description: Titanium alloys are being used increasingly in new generation aircraft, creating a market for high value components. It is argued that knowledge development is the key factor for South African machining suppliers to penetrate the global aerospace supply chains. This paper discusses current results of a collaborative project aiming at systematic research towards improved and more efficient utilisation of the High Speed Cutting (HSC), and particularly the High Performance Machining (HPM) technologies for selected titanium alloys. A process planning framework for milling of titanium alloys has been developed. Using as point of departure prominent tool demands, this framework combines a tool wear map approach and cost modelling that enables process planners as well as machine operators to act towards optimised machining. In this way the targeted cost minimisation and lead time shortening could be modelled and practically achieved.
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- Authors: Dimitrov, D. , Conradie, P.J.T. , Oosthuizen, G.
- Date: 2013
- Subjects: Titanium alloys , Milling , High speed cutting , High performance machining
- Type: Article
- Identifier: uj:4949 , http://hdl.handle.net/10210/13049
- Description: Titanium alloys are being used increasingly in new generation aircraft, creating a market for high value components. It is argued that knowledge development is the key factor for South African machining suppliers to penetrate the global aerospace supply chains. This paper discusses current results of a collaborative project aiming at systematic research towards improved and more efficient utilisation of the High Speed Cutting (HSC), and particularly the High Performance Machining (HPM) technologies for selected titanium alloys. A process planning framework for milling of titanium alloys has been developed. Using as point of departure prominent tool demands, this framework combines a tool wear map approach and cost modelling that enables process planners as well as machine operators to act towards optimised machining. In this way the targeted cost minimisation and lead time shortening could be modelled and practically achieved.
- Full Text:
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