Research Publications/Outputs
http://hdl.handle.net/10204/11481
2024-03-28T21:29:06ZMaterial characteristics of Ti-6AL-4V samples additively manufactured using laser-based direct energy deposition
http://hdl.handle.net/10204/13654
Material characteristics of Ti-6AL-4V samples additively manufactured using laser-based direct energy deposition
Willemse, MG; Siyasiya, CW; Marais, D; Venter, AM; Arthur, Nana KK
Although additive manufacturing is fast gaining traction in the industrial world as a reputable manufacturing technique to complement traditional mechanical machining, it still has problems such as porosity and residual stresses in components that give rise to cracking, distortion, and delamination, which are important issues to resolve in structural load-bearing applications. This research project focused on the characterization of the evolution of residual stresses in Ti-6Al-4V extra-low interstitial (ELI) additive-manufactured test samples. Four square thin-walled tubular samples were deposited on the same baseplate, using the direct energy deposition laser printing process, to different build heights. The residual stresses were analysed in the as-printed condition by the neutron diffraction technique and correlated to qualitative predictions obtained using the ANSYS software suite. Good qualitative agreement between the stress measurements and predictions were observed. Both approaches revealed the existence of large tensile stresses along the laser track direction at the sections that were built last, i.e., centre of the top layers of the samples. This in addition leads to large tensile stresses at the outer edges (corners) which would have the effect of separating the samples from the baseplate should the stresses exceed the yield strength of the material. Such extreme conditions did not occur in this study, but the stresses did lead to significant distortion of the baseplate. In general, the microstructures and spatial elemental mapping revealed a strong correlation between the macro-segregation of elemental V and the distribution of the ß-phase in the printed parts.
2023-02-01T00:00:00ZA synthesis of mercury research in the Southern Hemisphere, part 2: Anthropogenic perturbations
http://hdl.handle.net/10204/13653
A synthesis of mercury research in the Southern Hemisphere, part 2: Anthropogenic perturbations
Fisher, JA; Schneider, L; Fostier, A-H; Guerrero, S; Guimaraes, JD; Labuschagne, Casper; Leaner, JJ; Martin, Lynwill G; Mason, RP; Walters, Chavon R
Environmental mercury (Hg) contamination is a global concern requiring action at national scales. Scientific understanding and regulatory policies are underpinned by global extrapolation of Northern Hemisphere Hg data, despite historical, political, and socioeconomic differences between the hemispheres that impact Hg sources and sinks. In this paper, we explore the primary anthropogenic perturbations to Hg emission and mobilization processes that differ between hemispheres and synthesize current understanding of the implications for Hg cycling. In the Southern Hemisphere (SH), lower historical production of Hg and other metals implies lower present-day legacy emissions, but the extent of the difference remains uncertain. More use of fire and higher deforestation rates drive re-mobilization of terrestrial Hg, while also removing vegetation that would otherwise provide a sink for atmospheric Hg. Prevalent Hg use in artisanal and small-scale gold mining is a dominant source of Hg inputs to the environment in tropical regions. Meanwhile, coal-fired power stations continue to be a significant Hg emission source and industrial production of non-ferrous metals is a large and growing contributor. Major uncertainties remain, hindering scientific understanding and effective policy formulation, and we argue for an urgent need to prioritize research activities in under-sampled regions of the SH.
2023-05-01T00:00:00ZModular robotic arm for automation of SMME industrial press
http://hdl.handle.net/10204/13652
Modular robotic arm for automation of SMME industrial press
Naicker, Dhananathan M; Purdon, Kyla; Ramruthan, Kshir
Small South African manufacturing companies, endeavouring to benefit from Fourth Industrial Revolution (4IR) technologies, specifically automation, are restricted by exorbitant costs and the lack of know-how associated with automation. This project aims to develop affordable modular automation blocks that can couple with each other, using the OpenStructures grid, to provide customisable degrees of freedom tailored for specific automation applications. The cost of development is recovered, and the cost of maintenance is reduced through the reuse of these blocks over different automation applications. A key measure of effectiveness is a standardised mechanical and electrical interface for each block.
2023-11-01T00:00:00ZNano mechanical study on a single layer TiC/TI6Al4V-ELI composite manufactured with laser metal deposition
http://hdl.handle.net/10204/13651
Nano mechanical study on a single layer TiC/TI6Al4V-ELI composite manufactured with laser metal deposition
Ramasobane, P; Mashinini, MP; Masina, Bathusile N
This study investigated the nano mechanical properties of Ti6Al4V-ELI embraced with TiC particles, synthesized with in situ laser metal deposition technique. The 3.85% feed ratio fraction TiC/Ti6Al4V-ELI composite samples were manufactured at four varying energy densities. The beta grain boundary and the acicular alpha primary matrix were found to have diverse morphologies of carbide particles due to the in-situ reaction. The effect of energy density is observed on the microstructure and nano mechanical properties. An average off set of 650 nm was recorded after the nano-indentation in the matrix at a maximum load of 400 mN.
2023-11-01T00:00:00Z