Thesis
Extended finite element predictions for three dimensional modeling of fatigue crack growth in cold-worked holes
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000004060
Handle:
https://hdl.handle.net/2376/125245
Abstract
Cold working has been widely used for enhancing the fatigue life of open holes. The process imparts compressive residual stresses around the hole which slows down the progression of crack under cyclic loading conditions. In the present study, fatigue crack growth in open holes in R260 grade steel, a typical railroad material, has been analyzed using the Extended Finite Element Method (XFEM). Along with the experimental studies, numerical simulation emerges as a powerful tool to predict the fatigue crack growth in rail steel and may deliver important insights to consider more situations by saving time and cost. XFEM modifies the standard displacement-based approximation by adding enrichment functions in the crack region. The investigation explored the capability of the XFEM, for a plate containing plain hole (baseline), pad coined, or split-sleeve cold-worked hole using the commercial finite element package, Abaqus, as a means of fatigue crack growth under constant amplitude loading. The effect of residual stress redistribution has been added to the numerical model to accurately predict the crack evolution. Stress Intensity Factors (SIF) are obtained from the XFEM calculations and the crack growth is estimated until the SIF reaches the fracture toughness of the modeled coupon material. The obtained simulation results are in good agreement with the fatigue experimental results in terms of the fatigue crack growth rates for plain hole (baseline), pad coined, or split-sleeve cold-worked holes. Results from the performed analysis show that cold working of an open hole increases the fatigue life when compared to the one without residual stresses due to the delay of crack initiation and propagation. The results also indicated fatigue life increase almost by a factor of three during crack propagation due to split-sleeve cold expansion in correlation to the baseline and pad coined sample.
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Details
- Title
- Extended finite element predictions for three dimensional modeling of fatigue crack growth in cold-worked holes
- Creators
- Mohammad Salman Yasin
- Contributors
- Dae-Wook Kim (Advisor) - Washington State University, School of Engineering and Computer Science (VANC)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Engineering and Computer Science (VANC)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900890791601842
- Language
- English
- Resource Type
- Thesis