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Role of the quenched disorder in fracture front propagation
Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, Department of Physics.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
##### Abstract [en]

The process of materials fracture is not yet understood across all levels. This thesis contains detailed description on a model of in-plane fracture along with results obtained using this model. The results from the model are in very good agreement with experimental observations, both with respect to the static scaling of the front (morphology) and a dynamic study of the underlying processes. This is quite remarkable, considering our model is quasistatic, meaning that the dynamics are time independent.

Using this model, I have found two scaling regimes which corresponds to the two different regimes found experimentally for in-plane fracture. This is the first model to successfully reproduce these two scaling regimes, allowing us to clearly state the important processes in this constrained form of fracture. Only the geometry is constrained, any material obeying the quite general assumptions in the model should contain the same processes and fracture in the same way.

The results indicate that a percolation process is controlling the fracture on small scales. At larger scales, the elastic material properties leads to a stress concentration which eventually constrains damage formation to the immediate area near the fracture front. In the large scale regime I have measured a roughness exponent of

$\zeta$large = 0.39 ± 0.04 .

In the small scale regime, I show data consistent with and present evidence based on several different analyses for a roughness exponent of $\zeta$small = 2/3.

NTNU, 2013.
##### Series
Doctoral theses at NTNU, ISSN 1503-8181 ; 2013:81
Physics
##### Identifiers
ISBN: 978-82-471-4261-5 (printed version)ISBN: 978-82-471-4262-2 (electronic version)OAI: oai:DiVA.org:ntnu-20700DiVA: diva2:616406
##### Public defence
2013-03-22, 00:00
Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2013-04-16Bibliographically approved
##### List of papers
1. A model for stable interfacial crack growth
Open this publication in new window or tab >>A model for stable interfacial crack growth
2012 (English)In: IUPAP C20 CONFERENCE ON COMPUTATIONAL PHYSICS (CCP 2011), 2012, 012039- p.Conference paper (Refereed)
##### Abstract [en]

We present a model for stable crack growth in a constrained geometry. The morphology of such cracks show scaling properties consistent with self affinity. Recent experiments show that there are two distinct self-affine regimes, one on small scales whereas the other at large scales. It is believed that two different physical mechanisms are responsible for this. The model we introduce aims to investigate the two mechanisms in a single system. We do find two distinct scaling regimes in the model.

##### Series
, Journal of Physics Conference Series, ISSN 1742-6588 ; 402
##### Identifiers
urn:nbn:no:ntnu:diva-20694 (URN)10.1088/1742-6596/402/1/012039 (DOI)000314709800038 ()
##### Conference
23rd IUPAP C20 Conference on Computational Physics (CCP), OCT 30-NOV 03, 2011, Gatlinburg, TN
Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2013-04-16Bibliographically approved
2. Onset of localization in heterogeneous interfacial failure
Open this publication in new window or tab >>Onset of localization in heterogeneous interfacial failure
2012 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, Vol. 86, no 2, 025101- p.Article in journal (Refereed) Published
##### Abstract [en]

We study numerically the failure of an interface joining two elastic materials under load using a fiber bundle model connected to an elastic half space. We find that the breakdown process follows the equal load sharing fiber bundle model without any detectable spatial correlations between the positions of the failing fibers until localization sets in. Depending on the elastic constant describing the elastic half space, localization sets in before or after the critical load causing the interface to fail completely is reached. There is a crossover between failure due to localization and failure without spatial correlations when tuning the elastic constant, not a phase transition as has been proposed earlier. Also, contrary to earlier claims based on models different from ours, we find that a finite fraction of fibers must fail before the critical load is attained, even in the extreme localization regime, i.e., for very small elastic constant. We furthermore find that the critical load remains finite for all values of the elastic constant in the limit of an infinitely large system.

##### Identifiers
urn:nbn:no:ntnu:diva-20695 (URN)10.1103/PhysRevE.86.025101 (DOI)000307384200001 ()
##### Note

© 2013 American Physical Society

Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2013-04-16Bibliographically approved
3. Making the case of GPUs in courses on computational physics
Open this publication in new window or tab >>Making the case of GPUs in courses on computational physics
(English)Manuscript (preprint) (Other academic)
##### Identifiers
urn:nbn:no:ntnu:diva-20696 (URN)
Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2013-04-16Bibliographically approved
4. Universality classes in constrained crack growth
Open this publication in new window or tab >>Universality classes in constrained crack growth
(English)Manuscript (preprint) (Other academic)
##### Identifiers
urn:nbn:no:ntnu:diva-20697 (URN)
Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2013-04-16Bibliographically approved
5. Local dynamics of a randomly pinned crack front: A numerical study
Open this publication in new window or tab >>Local dynamics of a randomly pinned crack front: A numerical study
(English)Manuscript (preprint) (Other academic)
##### Identifiers
urn:nbn:no:ntnu:diva-20698 (URN)
Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2013-04-16Bibliographically approved
6. On the universality classes and scaling exponents found in interfacial brittle fracture
Open this publication in new window or tab >>On the universality classes and scaling exponents found in interfacial brittle fracture
(English)Manuscript (preprint) (Other academic)
##### Identifiers
urn:nbn:no:ntnu:diva-20699 (URN)
Available from: 2013-04-16 Created: 2013-04-16 Last updated: 2013-04-16Bibliographically approved

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