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Modeling of dynamic fracture problems using AL finite element formulation Abdelgalil, Abdelgader I.

Abstract

The problem of dynamic crack propagation is widely addressed in the literature. The few available analytical solutions are limited to simple and idealized geometries and loading conditions. On the other hand, major approximations and inconsistent assumptions exist in published numerical models. In this thesis, the problem of dynamic crack propagation is modeled using a fully coupled Arbitrary Lagrangian Eulerian (ALE) formulation. The ALE equilibrium equations are derived, discretized using isoparametric finite elements and implemented into an ALE dynamic fracture program (ALEFR), based on an implicit solution scheme. The advantage of the ALE formulation is that the computational grid (finite element mesh) may have an arbitrary motion with respect to the domain of the deformed body. Therefore, the complex nature of the developed boundary condition due to a propagating crack may now be modeled in a continuous and accurate manner. The process of creating new surfaces due to crack propagation is modeled by splitting material points. This allows for a more realistic representation of the actual physical process. The ALE boundary constraint is enforced on the free boundaries, including the continuously changing free crack surfaces, using a newly developed technique. The dynamic energy release rate is evaluated through the integration of material properties of Lagrangian grid material points. The developed formulations and techniques are then discretized and implemented into a finite element code. The developed code is tested by modeling dynamic stationary and propagating fracture problems.

Item Metadata

Title
Modeling of dynamic fracture problems using AL finite element formulation
Creator
Abdelgalil, Abdelgader I.
Publisher
University of British Columbia
Date Issued
2002
Description
The problem of dynamic crack propagation is widely addressed in the literature. The few available analytical solutions are limited to simple and idealized geometries and loading conditions. On the other hand, major approximations and inconsistent assumptions exist in published numerical models. In this thesis, the problem of dynamic crack propagation is modeled using a fully coupled Arbitrary Lagrangian Eulerian (ALE) formulation. The ALE equilibrium equations are derived, discretized using isoparametric finite elements and implemented into an ALE dynamic fracture program (ALEFR), based on an implicit solution scheme. The advantage of the ALE formulation is that the computational grid (finite element mesh) may have an arbitrary motion with respect to the domain of the deformed body. Therefore, the complex nature of the developed boundary condition due to a propagating crack may now be modeled in a continuous and accurate manner. The process of creating new surfaces due to crack propagation is modeled by splitting material points. This allows for a more realistic representation of the actual physical process. The ALE boundary constraint is enforced on the free boundaries, including the continuously changing free crack surfaces, using a newly developed technique. The dynamic energy release rate is evaluated through the integration of material properties of Lagrangian grid material points. The developed formulations and techniques are then discretized and implemented into a finite element code. The developed code is tested by modeling dynamic stationary and propagating fracture problems.
Extent
15599864 bytes
Genre
Thesis/Dissertation
Type
Text
File Format
application/pdf
Language
eng
Date Available
2009-09-29
Provider
Vancouver : University of British Columbia Library
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
DOI
10.14288/1.0090649
URI
http://hdl.handle.net/2429/13320
Degree
Doctor of Philosophy - PhD
Program
Mechanical Engineering
Affiliation
Applied Science, Faculty of; Mechanical Engineering, Department of
Degree Grantor
University of British Columbia
Graduation Date
2002-11
Campus
UBCV
Scholarly Level
Graduate
Aggregated Source Repository
DSpace

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Rights

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.