Brittle fracture simulation with boundary elements for computer graphics
Hahn D. 2017. Brittle fracture simulation with boundary elements for computer graphics. Institute of Science and Technology Austria.
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Thesis
| PhD
| Published
| English
Author
Supervisor
Department
Series Title
ISTA Thesis
Abstract
This thesis describes a brittle fracture simulation method for visual effects applications. Building upon a symmetric Galerkin boundary element method, we first compute stress intensity factors following the theory of linear elastic fracture mechanics. We then use these stress intensities to simulate the motion of a propagating crack front at a significantly higher resolution than the overall deformation of the breaking object. Allowing for spatial variations of the material's toughness during crack propagation produces visually realistic, highly-detailed fracture surfaces. Furthermore, we introduce approximations for stress intensities and crack opening displacements, resulting in both practical speed-up and theoretically superior runtime complexity compared to previous methods. While we choose a quasi-static approach to fracture mechanics, ignoring dynamic deformations, we also couple our fracture simulation framework to a standard rigid-body dynamics solver, enabling visual effects artists to simulate both large scale motion, as well as fracturing due to collision forces in a combined system. As fractures inside of an object grow, their geometry must be represented both in the coarse boundary element mesh, as well as at the desired fine output resolution. Using a boundary element method, we avoid complicated volumetric meshing operations. Instead we describe a simple set of surface meshing operations that allow us to progressively add cracks to the mesh of an object and still re-use all previously computed entries of the linear boundary element system matrix. On the high resolution level, we opt for an implicit surface representation. We then describe how to capture fracture surfaces during crack propagation, as well as separate the individual fragments resulting from the fracture process, based on this implicit representation. We show results obtained with our method, either solving the full boundary element system in every time step, or alternatively using our fast approximations. These results demonstrate that both of these methods perform well in basic test cases and produce realistic fracture surfaces. Furthermore we show that our fast approximations substantially out-perform the standard approach in more demanding scenarios. Finally, these two methods naturally combine, using the full solution while the problem size is manageably small and switching to the fast approximations later on. The resulting hybrid method gives the user a direct way to choose between speed and accuracy of the simulation.
Publishing Year
Date Published
2017-08-14
Publisher
Institute of Science and Technology Austria
Acknowledgement
ERC H2020 programme (grant agreement no. 638176)
First of all, let me thank my committee members, especially my supervisor, Chris
Wojtan, for supporting me throughout my PhD. Obviously, none of this work would
have been possible without you.
Furthermore, Thank You to all the people who have contributed to this work in various
ways, in particular Martin Schanz and his group for providing and supporting the
HyENA boundary element library, as well as Eder Miguel and Morten Bojsen-Hansen
for (repeatedly) proof reading and providing valuable suggestions during the writing
of this thesis.
I would also like to thank Bernd Bickel, and all the members – past and present – of his
and Chris’ research groups at IST Austria for always providing honest and insightful
feedback throughout many joint group meetings, as well as Christopher Batty, Eitan
Grinspun, and Fang Da for many insights into boundary element methods during our
collaboration.
As only virtual objects have been harmed in the process of creating this work, I would
like to acknowledge the Stanford scanning repository for providing the “Bunny” and
“Armadillo” models, the AIM@SHAPE repository for “Pierre’s hand, watertight”, and
S. Gainsbourg for the “Column” via Archive3D.net. Sorry for breaking these models
in many different ways.
Page
124
ISSN
IST-REx-ID
Cite this
Hahn D. Brittle fracture simulation with boundary elements for computer graphics. 2017. doi:10.15479/AT:ISTA:th_855
Hahn, D. (2017). Brittle fracture simulation with boundary elements for computer graphics. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:th_855
Hahn, David. “Brittle Fracture Simulation with Boundary Elements for Computer Graphics.” Institute of Science and Technology Austria, 2017. https://doi.org/10.15479/AT:ISTA:th_855.
D. Hahn, “Brittle fracture simulation with boundary elements for computer graphics,” Institute of Science and Technology Austria, 2017.
Hahn D. 2017. Brittle fracture simulation with boundary elements for computer graphics. Institute of Science and Technology Austria.
Hahn, David. Brittle Fracture Simulation with Boundary Elements for Computer Graphics. Institute of Science and Technology Austria, 2017, doi:10.15479/AT:ISTA:th_855.
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