Understanding failure mechanics of mechanical equipment is one of the most important aspects of structural and aerospace engineering. Crack growth being one of the major forms of failure in structural components has been studied for several decades to achieve greater reliability and guarantee higher safety standards.
Conventional approaches using the finite element framework provides accurate solutions, yet they require extremely complicated numerical approaches or highly fine mesh densities which is computationally expensive and yet suffers from several numerical instabilities such as element entanglement or overly soften element behavior. The eXtended Finite Element Method (XFEM) is a relatively recent concept developed for modeling geometric discontinuities and singularities by introducing the addition of new terms to the classical shape functions in order to allow the finite element formulation to remain the same. XFEM does not require the necessity of computationally expensive numerical schemes such as active remeshing and allows for easier crack representation.
In this work, verifies the validity of this new concept for quasi-static crack growth in tension with Abaqus' XFEM is employed. In the course of the work, the effect of various parameters that are involved in the modelling of the crack are parametrically analyzed.
The load-displacement data and crack growth were used as the comparison criterion. It was found that XFEM is unable to accurately represent crack growth in the models in the elastic region without direct manipulation of the material properties. The crack growth in the plastic region is found to be affected by certain parameters allowing us to tailor the model to a small degree. This thesis attempts to provide a greater understanding into the parametric dependencies of XFEM crack growth. / Master of Science / Crack propagation is one of the major causes of failure in equipment in structural and aerospace engineering. The study of fracture and crack growth has been taking place for decades in an effort to increase quality of design and to ensure higher standards of safety.
In the past, an accurate representation of crack growth within a specimen using conventional numerical analysis was computationally expensive. The eXtended Finite Element Method (XFEM) is a concept introduced that would reduce computational effort yet improving the fidelity of the analysis while allowing for easier representation of crack growth.
This thesis, verifies the validity of XFEM in simulating crack growth in a specimen undergoing tension using a commercially available code, Abaqus. The various parameters involved in the modeling of this crack and their effects are studied. The study had shown that the inaccuracy of XFEM in its ability to model crack growth, however, it gives us some understanding into certain parameters that would allow us to tailor the model to better represent experimental data.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/78724 |
| Date | 21 August 2017 |
| Creators | Prasanna Kumar, Siddharth |
| Contributors | Mechanical Engineering, Bayandor, Javid, Mirzaeifar, Reza, West, Robert L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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