Nickey Janse van Rensburg

Static Analysis of Advanced Composites for the Optimal Design of an Experimental Lightweight Solar Vehicle Suspension System

To create an energy efficient vehicle there are a number of aspects that need to be optimized, namely; the drive train of the vehicle and energy source, aerodynamics and weight. Focusing on weight reduction, while still maintaining the desired performance and structural strength, many manufacturers are turning to advanced composites due to their superior strength to weight characteristics. Solar car racing provides a research platform that drives this innovation through technology development and efficiency. A lightweight vehicle suspension system design is being presented, together with an introduction into future testing. A suspension system is made up of a number of critical components which are dynamically loaded during standard operation due to undulating forces imposed by the road surface. Unidirectional cross-wound carbon fiber tubing is used for suspension and steering arms. The tubing is interfaced with small steel inserts and pivoting arm tie rod ends. Concerns within the design are the adhesive bonding of the carbon tubing to the steel inserts, and what type of tensile loading the interface can withstand. Due to forces imposed on the system during cornering and shock loading the components are required to withstand a minimum of 1.2 times the weight of the overall vehicle, i.e. 258 kg. Tensile test results show that the mechanical properties of the adhesive joints rely somewhat on the surface characteristics and bond preparation. The target load of 258 kg was successfully obtained under static loading for two types of sample sets. The first based on the standard for describing the lap shear strength of adhesively bonded carbon fiber to aluminum, and the second based on the working component itself.Copyright

Numerical Assessment of the Aerodynamic Properties of a Solar Vehicle

Due to wide emphasis on climate change today, alternative fuel research is necessary. Consequently, the South African Solar Challenge has created a competitive platform for research into alternative energies, particularly solar. The University of Johannesburg (UJ) competed in the competition using their uniquely designed and built solar vehicle, Ilanga I. However, due to the constraints of the energy available, the aerodynamics of the vehicle has to be exceptionally good. Subsequently, a large proportion of the total power of the vehicle is used to overcome the aerodynamic resistance posed by the vehicle. Furthermore, much of the remaining power of the vehicle is used to overcome rolling resistance. Consequently, solar vehicles have to be as lightweight as possible in order to effectively reduce the rolling resistance. However, reducing weight of the vehicle results in the vehicle’s stability being greatly affected by side-wind effects. In order to improve on the vehicle, it is very important to test for and obtain its aerodynamic characteristics. This research article aims at obtaining the average drag coefficient felt during the majority of the race as well as the lift coefficients for side-wind cases, in order to investigate vehicle safety. Thus, through the use of Computational Fluid Dynamics (CFD), it was possible to obtain an assessment of the vehicle’s performance. Simulations were performed using the Reynold’s Averaged Navier Stokes (RANS) method with use of the k-ω SST turbulence model. This method of simulation showed reasonable predictions of the results as compared to literature.Copyright

Engineering students' visual metaphors for mentorship: Implications for the candidacy period

Mentorship is important to engineering activity. Yet, little attention is paid to this process within the engineering domain. This paper seeks to remedy this by analyzing the metaphors for mentorship produced by engineering students employed to work as mentors to young adults tasked with training residents in their communities regarding specific digital skills. Metaphors are used because they provide unique insight into the underlying conceptions that individuals hold about a topic or issue. The paper shows not only that metaphors are useful in garnering understanding as to how students conceive of the mentor-mentee relationship, but also that there is scope for using these understandings to provide more focused mentoring during their future candidacy period.

Understanding the Impact of Engineering Through Appropriate Technology Development

This research describes a pilot project which aimed to introduce CDIO-type (Conceive-Design-Implement-Operate), project-based learning through a community-based project in a third year Material Science module. The project formed part of an agriculture research initiative, and relied on interdisciplinary research collaboration between engineering, social sciences, management, entrepreneurship, and industrial arts. The initiative seeks to develop an agribusiness solution that will create an open-market, growth-oriented food economy. As part of the initiative, engineering students, participating in teams, worked alongside a community of urban farmers, most of whom are working poor, so as to develop appropriate, intermediate technology/ies that could support the farmers. This was informed by the need to have students demonstrate high level understanding of disciplinary content, but also to engage in human-centered design thinking and practice.Copyright

Systems Engineering Education in an Accredited Undergraduate Engineering Program

Developing countries are mostly reliant on external technologies and this augments the need for systems engineering capability in these economies. It is therefore imperative that systems engineering as theory and practice is included in undergraduate engineering curricula to strengthen the internal technological capability of a country’s developing engineers. In South Africa, the quality of undergraduate engineering programs is governed by the Engineering Council of South Africa (affiliated under the Washington Accord); and the exit level outcomes of the programs are predetermined explicitly per module. Systems engineering was introduced to an undergraduate electrical engineering program offered in the Faculty of Engineering and the Built Environment at the University of Johannesburg; and a framework developed to ensure that the program still meets the requisite ECSA exit level outcomes and therefore international standards. This paper presents the design and implementation of the framework, as well as the challenges that students are exposed to when faced with real-world systems engineering practice. Students were grouped into independent product development teams using a software support tool which promotes diversity and skill-level targets for each team. The independent team structure required the use and application of the systems engineering process and supported the development of management and communication skills. Furthermore, the framework allowed assessment of the performance of each product development team towards achieving the overall project objectives. One of the accreditation requirements of undergraduate engineering programs is peer assessment and this was achieved by the process. The paper closes by presenting the results of the stated framework implementation in an undergraduate electrical engineering program offered in the Faculty of Engineering and the Built Environment at the University of Johannesburg.Copyright

Simplified encapsulation of solar cells using glass fibre reinforced polymers

This paper presents a simplified method of solar cell encapsulation using glass fibre reinforced polymers (GFRP). The method investigated is focused on affordability, efficiency, the use of basic equipment and a fast turn around time for manufacture with basic skill requirements. The fast and inexpensive method was put to the test when a full scale, 6 m2, solar array was implemented on a solar-powered electric vehicle. The method has been developed using half cells in raw form, assembled in uniform modules. A number of electrical, thermal and mechanical tests have been conducted to determine the comparative durability and output of the encapsulated cells prior to implementation on the solar vehicle. The tests aided in characterising the benefits of composites for this application, and ultimately to finalise the composite layup and tweak the process. Since then, the vehicle competed in the 2012 South African Solar Challenge (SASC), a biennial endurance event spanning 4900 km of South African roads over a period of two weeks. Exposed to ambient temperature variations of between 5 and 40 °C, rain, road vibration and shock from the odd pothole, the race proved to be an adequate test for the durability and reliability of the array. The method proposed in this paper could be used to encapsulate cells for other applications where a lightweight and inexpensive array is required, such as portable power generation.