E-Thesis 71 views
Effect of Defects on the HCF Behaviour of Ti-6Al-4V / ANDREW KILLEN
Swansea University Author: ANDREW KILLEN
DOI (Published version): 10.23889/SUThesis.66150
Abstract
This research examines the high-cycle fatigue characteristics of Ti-6Al-4V, a titanium alloy with an equiaxed fine grain structure, with a particular focus on the influence of Focused Ion Beam (FIB) induced notches. The investigation reveals that the specific design and geometry of these FIB notches...
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Swansea University, Wales, UK
2024
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | EngD |
| Supervisor: | Whittaker, M.; Davies, H.; and Friend, G. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa66150 |
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| Abstract: |
This research examines the high-cycle fatigue characteristics of Ti-6Al-4V, a titanium alloy with an equiaxed fine grain structure, with a particular focus on the influence of Focused Ion Beam (FIB) induced notches. The investigation reveals that the specific design and geometry of these FIB notches, aligned to the grain size of Ti-6Al-4V, critically impacts its fatigue properties. The creation of these artificial defects through FIB significantly accelerates the onset of crack formation, with evidence suggesting a strong interaction with the material’s inherent microstructure. The depth and extent of these notches have a direct bearing on the fatigue lifespan, with deeper notches causing more pronounced reductions. Through the √Area parameter model, it was possible to effectively predict material failure with artificial micro level defects. However, it also revealed possible shortcomings in the traditional understanding of stress concentration factors, particularly when considering notch-induced behaviour. This study also highlights the possible limitations inherent to advanced Non-Destructive Testing (NDT) techniques. Despite the effectiveness of traditional NDT methods, they can sometimes miss certain micro level surface defects. This raises questions about the reliability of these methods, underlining the necessity for enhanced training and a deeper exploration into defect geometries that typically present detection challenges, especially in critical aerospace applications, including fan blades within a gas turbine engine, which have paramount safety implications. |
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| Keywords: |
Materials, Aerospace |
| College: |
Faculty of Science and Engineering |
| Funders: |
Rolls-Royce plc, M2A |