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Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V
The focus of this research project was to determine experimentally the fatigue and fracture toughness characteristic, from a fracture mechanics perspective, of Ti-6Al-4V titanium alloy manufactured by Selective Laser Melting (SLM). Three build orientations are considered where a fatigue crack is gro...
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| Format: | Thesis |
| Language: | English |
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Centre for Minerals Research
2017
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| _version_ | 1867613344209305600 |
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| access_status_str | Open Access |
| author | Dhansay, Nur Mohamed |
| author2 | Tait, Robert B |
| author_browse | Dhansay, Nur Mohamed Tait, Robert B |
| author_facet | Tait, Robert B Dhansay, Nur Mohamed |
| author_sort | Dhansay, Nur Mohamed |
| collection | Thesis |
| description | The focus of this research project was to determine experimentally the fatigue and fracture toughness characteristic, from a fracture mechanics perspective, of Ti-6Al-4V titanium alloy manufactured by Selective Laser Melting (SLM). Three build orientations are considered where a fatigue crack is grown parallel and two are grown perpendicular to the build orientation. The project then endeavours to generate a fracture mechanics based Paris equation from the fatigue crack growth rate results and together with the fracture toughness, fatigue life predictions may be determined based on crack propagation lifetimes. SLM is an Additive Manufacturing (AM) technique whereby an object is fabricated in a layerwise manner via the use of lasers, directly from a 3D CAD model. This process allows for the manufacture of complex designs in its net or near net shape form, which is not possible with conventional manufacturing techniques. There are minimal amounts of material wastage and it potentially eliminates post manufacture machining and processing costs. Ti- 6Al-4V is used in many applications where high strength at low density is required at moderate temperatures. Corrosion resistance qualities of the alloy are also considered for many applications. Some of the applications where this alloy is used include turbine engine components, aircraft structural components, aerospace fasteners, high-performance automotive parts, marine applications, medical implant devices and sports equipment. Due to the large use of the alloy in industry and with the potential benefits of manufacturing by SLM, there is a great need for investigating SLM Ti-6Al-4V as a viable alternative to conventional casting, forging and machining. There is limited literature covering the fatigue crack growth rate and fracture toughness of SLM Ti-6Al-4V and the effect of build orientation on these characteristics. However, it is clear, from the limited available literature that fatigue crack growth rate behaviour is affected by build orientation, and so this project investigates the effect of these orientations, and aims to contribute to understanding why these orientation effects occur. Since there is even less literature available on the fracture toughness of SLM Ti-6Al-4V with respect to build orientation, this project also endeavours to characterise orientation effects on fracture toughness, if any, and compares these with those of conventionally manufacture Ti-6Al-4V. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/24326 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:34:39.078Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Centre for Minerals Research |
| publisherStr | Centre for Minerals Research |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/24326 Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V Dhansay, Nur Mohamed Tait, Robert B Becker, Thorsten Mechanical Engineering Minerals Engineering The focus of this research project was to determine experimentally the fatigue and fracture toughness characteristic, from a fracture mechanics perspective, of Ti-6Al-4V titanium alloy manufactured by Selective Laser Melting (SLM). Three build orientations are considered where a fatigue crack is grown parallel and two are grown perpendicular to the build orientation. The project then endeavours to generate a fracture mechanics based Paris equation from the fatigue crack growth rate results and together with the fracture toughness, fatigue life predictions may be determined based on crack propagation lifetimes. SLM is an Additive Manufacturing (AM) technique whereby an object is fabricated in a layerwise manner via the use of lasers, directly from a 3D CAD model. This process allows for the manufacture of complex designs in its net or near net shape form, which is not possible with conventional manufacturing techniques. There are minimal amounts of material wastage and it potentially eliminates post manufacture machining and processing costs. Ti- 6Al-4V is used in many applications where high strength at low density is required at moderate temperatures. Corrosion resistance qualities of the alloy are also considered for many applications. Some of the applications where this alloy is used include turbine engine components, aircraft structural components, aerospace fasteners, high-performance automotive parts, marine applications, medical implant devices and sports equipment. Due to the large use of the alloy in industry and with the potential benefits of manufacturing by SLM, there is a great need for investigating SLM Ti-6Al-4V as a viable alternative to conventional casting, forging and machining. There is limited literature covering the fatigue crack growth rate and fracture toughness of SLM Ti-6Al-4V and the effect of build orientation on these characteristics. However, it is clear, from the limited available literature that fatigue crack growth rate behaviour is affected by build orientation, and so this project investigates the effect of these orientations, and aims to contribute to understanding why these orientation effects occur. Since there is even less literature available on the fracture toughness of SLM Ti-6Al-4V with respect to build orientation, this project also endeavours to characterise orientation effects on fracture toughness, if any, and compares these with those of conventionally manufacture Ti-6Al-4V. 2017-05-16T08:01:40Z 2017-05-16T08:01:40Z 2015 Master Thesis Masters MSc (Eng) http://hdl.handle.net/11427/24326 eng application/pdf Centre for Minerals Research Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Mechanical Engineering Minerals Engineering Dhansay, Nur Mohamed Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V |
| thesis_degree_str | Master's |
| title | Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V |
| title_full | Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V |
| title_fullStr | Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V |
| title_full_unstemmed | Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V |
| title_short | Fracture mechanics based fatigue and fracture toughness evaluation of SLM Ti-6Al-4V |
| title_sort | fracture mechanics based fatigue and fracture toughness evaluation of slm ti 6al 4v |
| topic | Mechanical Engineering Minerals Engineering |
| url | http://hdl.handle.net/11427/24326 |
| work_keys_str_mv | AT dhansaynurmohamed fracturemechanicsbasedfatigueandfracturetoughnessevaluationofslmti6al4v |