N. Janse van Rensburg

High speed machining induced residual stresses in Grade 5 titanium alloy

The surface and near surface residual stress state induced by machining may have a significant effect on the structural integrity of some important mechanical components. This article describes an experimental investigation of this stress state during high speed machining of Grade 5 titanium alloy (Ti6Al4V). The size and depth of the stress field is evaluated by non-contact probing measurement techniques as a function of cutting speed (70–200 m/min) and depth of cut (0.25–1.0 mm). X-ray diffraction and synchrotron energy dispersive diffraction are used to evaluate the surface (X-ray diffraction) and sub-surface (energy dispersive diffraction) residual stress fields. The results indicate that both techniques may be successfully employed to evaluated machining induced residual stress fields and that the energy dispersive diffraction method is eminently suitable for probe depths up to 100 µm in Grade 5. The results clearly indicated that significant residual stresses are introduced during machining both at conventional and high cutting speeds. The stresses are largely compressive and aligned with the main cutting direction for both rough and finish cuts. The results also show that the residual stress level is a strong function of the cutting speed. The overall stress level effectively becomes more tensile but also decreases with increasing cutting speed.

Social innovation, research and community engagement: Managing interdisciplinary projects for societal change

A transformative research paradigm is rooted in knowledge mobilization processes involving close collaboration between researchers and the community. A formalized approach to managing multi-stakeholder participation and community engagement in a science and technology research environment is presented. Design science research methodology is applied with a systems thinking approach to implement an integrated research, development and project management network at a tertiary education institution. The network is presented as a Research and Projects Office that enables a projects-based approach to facilitate interdisciplinary and community-driven research for social change through technology development.

Taking on the challenge: Evaluating the benefits of participating in solar vehicle racing

Solar Challenge events are hosted around the world with growing numbers of teams competing with solar powered electric vehicles designed and built by engineering students. These projects are resource intensive and require a great deal of effort and commitment from everyone involved. The purpose of the research is to comment on the value of participating in these events and to evaluate student participation in the South African Solar Challenge event as a cooperative learning environment. The research comments on the impact of the Solar Challenge on the student learning experience.

EXPLORING THE SAFE HUMAN MINDSET OF PRODUCTION LEADERS OF A PLATINUM MINE

The aim of this research was to determine the safety mindset of managers, shift bosses, and miners as the production leaders in a South African platinum mine. The Safe Human Mindset Measuring Instrument (SHMI) was administered among a purposive selected sample of managers, shift bosses and miners (N=106). Results showed significant differences between managers and miners in terms of relationship credibility, climate, trust, caring support, ownership, physical work environment, and attitude to safety. Significant differences were also found between managers and shift bosses in terms of trust and caring support, and between shift bosses and miners in terms of ownership. Practical implications are discussed and recommendations are made. OPSOMMING Die doel van die navorsing was om die houding van bestuurders, skofbestuurders en mynwerkers as produksieleiers in ’n Suid-Afrikaanse platinummyn ten opsigte van menslike veiligheid te bepaal. Die Veilige Menslike Houdingsinstrument is onder ’n doelbewuste steekproef van bestuurders, skofbestuurders en mynwerkers afgeneem (N=106). Die resultate het getoon dat betekenisvolle verskille bestaan tussen bestuurders en mynwerkers in terme van betroubare verhoudinge, klimaat, vertroue, ondersteuning, fisiese werksomgewing, en houding ten opsigte van veiligheid. Betekenisvolle verskille is ook gevind tussen bestuurders en skofbestuurders in terme van vertroue en ondersteuning, en tussen skofbestuurders en mynwerkers in terme van eienaarskap. Praktiese implikasies word bespreek en aanbevelings gemaak. a a a a a a a a a a a a a a a a aa a a a

Developing Students as Higher-Order Thinkers: Analyzing Student Performance Against Levels of Cognitive Demand in a Material Science Course

Today’s increasingly complex engineering workplace demands skill in evaluation, reasoning and critical thinking; however, engineering curricula often test lower-order learning at the expense of higher-order reasoning. This paper analyzes the level of cognitive demand in a course on Material Science in the Department of Mechanical Engineering Science at the University of Johannesburg, South Africa. This is done by applying Biggs’ SOLO taxonomy to classify test and exam questions in the course and then analyzing student performance against this taxonomy of higher- and lower-order learning. The results demonstrate that many students battle with questions that require extended abstract reasoning (argument, evaluation, hypothesizing and generalization). Similarly, relational thinking (through comparison, contrast, application and so on) proves to be a significant problem for weaker students. The paper recommends that engineering lecturers build higher-order thinking into course outcomes, teaching and assessment and that engineering qualifications work systematically towards developing students as higher-order thinkers.Copyright