Fracture mechanics analysis methods
In this study, fracture mechanic analysis method was reviewed for the program development of the automated calculation of fatigue life cycles prediction. An integral expression was first developed from Paris’ law fatigue crack growth equation, followed by setting up an integration function in Excel...
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| Format: | Final Year Project (FYP) |
| Language: | English |
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Nanyang Technological University
2020
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| Online Access: | https://hdl.handle.net/10356/141725 |
| _version_ | 1826114703089205248 |
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| author | Ng, Chun Da |
| author2 | Pang Hock Lye, John |
| author_facet | Pang Hock Lye, John Ng, Chun Da |
| author_sort | Ng, Chun Da |
| collection | NTU |
| description | In this study, fracture mechanic analysis method was reviewed for the program development of the automated calculation of fatigue life cycles prediction. An integral expression was first developed from Paris’ law fatigue crack growth equation, followed by setting up an integration function in Excel spreadsheet using trapezoidal rule and Excel VBA to integrate the expression to determine the predicted fatigue lifespan (cycles). A UserForm was designed to facilitate data inputs and outputs display with a graphical plot of crack length vs fatigue life cycles. Influence of material constants C & m for two rail steel grades (R260, R350HT) at the head, web and foot were investigated and compared to establish critical values for both steel grades. The Stress Intensity Factor (SIFs) expressed in term of geometric Y factor developed by Y. Liu was used to investigate the effects of different crack angle, crack initiation location and loading type, each producing a specific trend in fatigue life cycles for the respective variable. The effect of critical stress on resulting fatigue life cycles was also studied and the results are characterised by a reverse exponential trend in fatigue lifespan with increasing stress value. Parametric studies were conducted extensively to ensure consistency in the results. The graphical plot of crack length vs fatigue life cycles provides an insight on crack growth trend which shows exponential crack propagation at a faster rate when the crack length grows beyond 1mm. |
| first_indexed | 2024-10-01T03:43:49Z |
| format | Final Year Project (FYP) |
| id | ntu-10356/141725 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T03:43:49Z |
| publishDate | 2020 |
| publisher | Nanyang Technological University |
| record_format | dspace |
| spelling | ntu-10356/1417252023-03-04T19:23:28Z Fracture mechanics analysis methods Ng, Chun Da Pang Hock Lye, John School of Mechanical and Aerospace Engineering MHLPANG@ntu.edu.sg Engineering::Mechanical engineering In this study, fracture mechanic analysis method was reviewed for the program development of the automated calculation of fatigue life cycles prediction. An integral expression was first developed from Paris’ law fatigue crack growth equation, followed by setting up an integration function in Excel spreadsheet using trapezoidal rule and Excel VBA to integrate the expression to determine the predicted fatigue lifespan (cycles). A UserForm was designed to facilitate data inputs and outputs display with a graphical plot of crack length vs fatigue life cycles. Influence of material constants C & m for two rail steel grades (R260, R350HT) at the head, web and foot were investigated and compared to establish critical values for both steel grades. The Stress Intensity Factor (SIFs) expressed in term of geometric Y factor developed by Y. Liu was used to investigate the effects of different crack angle, crack initiation location and loading type, each producing a specific trend in fatigue life cycles for the respective variable. The effect of critical stress on resulting fatigue life cycles was also studied and the results are characterised by a reverse exponential trend in fatigue lifespan with increasing stress value. Parametric studies were conducted extensively to ensure consistency in the results. The graphical plot of crack length vs fatigue life cycles provides an insight on crack growth trend which shows exponential crack propagation at a faster rate when the crack length grows beyond 1mm. Bachelor of Engineering (Mechanical Engineering) 2020-06-10T04:55:02Z 2020-06-10T04:55:02Z 2020 Final Year Project (FYP) https://hdl.handle.net/10356/141725 en C082 application/pdf Nanyang Technological University |
| spellingShingle | Engineering::Mechanical engineering Ng, Chun Da Fracture mechanics analysis methods |
| title | Fracture mechanics analysis methods |
| title_full | Fracture mechanics analysis methods |
| title_fullStr | Fracture mechanics analysis methods |
| title_full_unstemmed | Fracture mechanics analysis methods |
| title_short | Fracture mechanics analysis methods |
| title_sort | fracture mechanics analysis methods |
| topic | Engineering::Mechanical engineering |
| url | https://hdl.handle.net/10356/141725 |
| work_keys_str_mv | AT ngchunda fracturemechanicsanalysismethods |