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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Main Author: Ng, Chun Da
Other Authors: Pang Hock Lye, John
Format: Final Year Project
Language:English
Published: Nanyang Technological University 2020
Subjects:
Online Access:https://hdl.handle.net/10356/141725
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.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
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Mechanical engineering
spellingShingle Engineering::Mechanical engineering
Ng, Chun Da
Fracture mechanics analysis methods
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.
author2 Pang Hock Lye, John
author_facet Pang Hock Lye, John
Ng, Chun Da
format Final Year Project
author Ng, Chun Da
author_sort Ng, Chun Da
title Fracture mechanics analysis methods
title_short Fracture mechanics analysis methods
title_full Fracture mechanics analysis methods
title_fullStr Fracture mechanics analysis methods
title_full_unstemmed Fracture mechanics analysis methods
title_sort fracture mechanics analysis methods
publisher Nanyang Technological University
publishDate 2020
url https://hdl.handle.net/10356/141725
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