--- _id: '839' abstract: - lang: eng text: '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. ' acknowledgement: "ERC H2020 programme (grant agreement no. 638176)\r\nFirst of all, let me thank my committee members, especially my supervisor, Chris\r\nWojtan, for supporting me throughout my PhD. Obviously, none of this work would\r\nhave been possible without you.\r\nFurthermore, Thank You to all the people who have contributed to this work in various\r\nways, in particular Martin Schanz and his group for providing and supporting the\r\nHyENA boundary element library, as well as Eder Miguel and Morten Bojsen-Hansen\r\nfor (repeatedly) proof reading and providing valuable suggestions during the writing\r\nof this thesis.\r\nI would also like to thank Bernd Bickel, and all the members – past and present – of his\r\nand Chris’ research groups at IST Austria for always providing honest and insightful\r\nfeedback throughout many joint group meetings, as well as Christopher Batty, Eitan\r\nGrinspun, and Fang Da for many insights into boundary element methods during our\r\ncollaboration.\r\nAs only virtual objects have been harmed in the process of creating this work, I would\r\nlike to acknowledge the Stanford scanning repository for providing the “Bunny” and\r\n“Armadillo” models, the AIM@SHAPE repository for “Pierre’s hand, watertight”, and\r\nS. Gainsbourg for the “Column” via Archive3D.net. Sorry for breaking these models\r\nin many different ways.\r\n" alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: David full_name: Hahn, David id: 357A6A66-F248-11E8-B48F-1D18A9856A87 last_name: Hahn citation: ama: Hahn D. Brittle fracture simulation with boundary elements for computer graphics. 2017. doi:10.15479/AT:ISTA:th_855 apa: 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 chicago: 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. ieee: D. Hahn, “Brittle fracture simulation with boundary elements for computer graphics,” Institute of Science and Technology Austria, 2017. ista: Hahn D. 2017. Brittle fracture simulation with boundary elements for computer graphics. Institute of Science and Technology Austria. mla: 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. short: D. Hahn, Brittle Fracture Simulation with Boundary Elements for Computer Graphics, Institute of Science and Technology Austria, 2017. date_created: 2018-12-11T11:48:47Z date_published: 2017-08-14T00:00:00Z date_updated: 2024-02-21T13:48:02Z day: '14' ddc: - '004' - '005' - '006' - '531' - '621' degree_awarded: PhD department: - _id: ChWo doi: 10.15479/AT:ISTA:th_855 ec_funded: 1 file: - access_level: open_access checksum: 6c1ae8c90bfaba5e089417fefbc4a272 content_type: application/pdf creator: system date_created: 2018-12-12T10:14:46Z date_updated: 2020-07-14T12:48:13Z file_id: '5100' file_name: IST-2017-855-v1+1_thesis_online_pdfA.pdf file_size: 14596191 relation: main_file - access_level: closed checksum: 421672f68d563b029869c5cf1713f919 content_type: application/zip creator: dernst date_created: 2019-04-05T08:40:30Z date_updated: 2020-07-14T12:48:13Z file_id: '6207' file_name: 2017_thesis_Hahn_source.zip file_size: 15060566 relation: source_file file_date_updated: 2020-07-14T12:48:13Z has_accepted_license: '1' language: - iso: eng license: https://creativecommons.org/licenses/by-sa/4.0/ month: '08' oa: 1 oa_version: Published Version page: '124' project: - _id: 2533E772-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '638176' name: Efficient Simulation of Natural Phenomena at Extremely Large Scales publication_identifier: issn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria publist_id: '6809' pubrep_id: '855' related_material: record: - id: '1362' relation: part_of_dissertation status: public - id: '1633' relation: part_of_dissertation status: public - id: '5568' relation: popular_science status: public status: public supervisor: - first_name: Christopher J full_name: Wojtan, Christopher J id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87 last_name: Wojtan orcid: 0000-0001-6646-5546 title: Brittle fracture simulation with boundary elements for computer graphics tmp: image: /images/cc_by_sa.png legal_code_url: https://creativecommons.org/licenses/by-sa/4.0/legalcode name: Creative Commons Attribution-ShareAlike 4.0 International Public License (CC BY-SA 4.0) short: CC BY-SA (4.0) type: dissertation user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 year: '2017' ... --- _id: '5568' abstract: - lang: eng text: Includes source codes, test cases, and example data used in the thesis Brittle Fracture Simulation with Boundary Elements for Computer Graphics. Also includes pre-built binaries of the HyENA library, but not sources - please contact the HyENA authors to obtain these sources if required (https://mech.tugraz.at/hyena) article_processing_charge: No author: - first_name: David full_name: Hahn, David id: 357A6A66-F248-11E8-B48F-1D18A9856A87 last_name: Hahn citation: ama: 'Hahn D. Source codes: Brittle fracture simulation with boundary elements for computer graphics. 2017. doi:10.15479/AT:ISTA:73' apa: 'Hahn, D. (2017). Source codes: Brittle fracture simulation with boundary elements for computer graphics. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:73' chicago: 'Hahn, David. “Source Codes: Brittle Fracture Simulation with Boundary Elements for Computer Graphics.” Institute of Science and Technology Austria, 2017. https://doi.org/10.15479/AT:ISTA:73.' ieee: 'D. Hahn, “Source codes: Brittle fracture simulation with boundary elements for computer graphics.” Institute of Science and Technology Austria, 2017.' ista: 'Hahn D. 2017. Source codes: Brittle fracture simulation with boundary elements for computer graphics, Institute of Science and Technology Austria, 10.15479/AT:ISTA:73.' mla: 'Hahn, David. Source Codes: Brittle Fracture Simulation with Boundary Elements for Computer Graphics. Institute of Science and Technology Austria, 2017, doi:10.15479/AT:ISTA:73.' short: D. Hahn, (2017). datarep_id: '73' date_created: 2018-12-12T12:31:35Z date_published: 2017-08-16T00:00:00Z date_updated: 2024-02-21T13:48:02Z day: '16' ddc: - '004' department: - _id: ChWo doi: 10.15479/AT:ISTA:73 ec_funded: 1 file: - access_level: open_access checksum: 2323a755842a3399cbc47d76545fc9a0 content_type: application/zip creator: system date_created: 2018-12-12T13:02:57Z date_updated: 2020-07-14T12:47:04Z file_id: '5615' file_name: IST-2017-73-v1+1_FractureRB_v1.1_2017_07_20_final_public.zip file_size: 199353471 relation: main_file file_date_updated: 2020-07-14T12:47:04Z has_accepted_license: '1' keyword: - Boundary elements - brittle fracture - computer graphics - fracture simulation month: '08' oa: 1 oa_version: Published Version project: - _id: 2533E772-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '638176' name: Efficient Simulation of Natural Phenomena at Extremely Large Scales publisher: Institute of Science and Technology Austria related_material: record: - id: '839' relation: research_paper status: public status: public title: 'Source codes: Brittle fracture simulation with boundary elements for computer graphics' tmp: image: /images/cc_by_sa.png legal_code_url: https://creativecommons.org/licenses/by-sa/4.0/legalcode name: Creative Commons Attribution-ShareAlike 4.0 International Public License (CC BY-SA 4.0) short: CC BY-SA (4.0) type: research_data user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 year: '2017' ... --- _id: '1361' abstract: - lang: eng text: We propose a novel surface-only technique for simulating incompressible, inviscid and uniform-density liquids with surface tension in three dimensions. The liquid surface is captured by a triangle mesh on which a Lagrangian velocity field is stored. Because advection of the velocity field may violate the incompressibility condition, we devise an orthogonal projection technique to remove the divergence while requiring the evaluation of only two boundary integrals. The forces of surface tension, gravity, and solid contact are all treated by a boundary element solve, allowing us to perform detailed simulations of a wide range of liquid phenomena, including waterbells, droplet and jet collisions, fluid chains, and crown splashes. alternative_title: - ACM Transactions on Graphics article_number: a78 author: - first_name: Fang full_name: Da, Fang last_name: Da - first_name: David full_name: Hahn, David id: 357A6A66-F248-11E8-B48F-1D18A9856A87 last_name: Hahn - first_name: Christopher full_name: Batty, Christopher last_name: Batty - first_name: Christopher J full_name: Wojtan, Christopher J id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87 last_name: Wojtan orcid: 0000-0001-6646-5546 - first_name: Eitan full_name: Grinspun, Eitan last_name: Grinspun citation: ama: 'Da F, Hahn D, Batty C, Wojtan C, Grinspun E. Surface only liquids. In: Vol 35. ACM; 2016. doi:10.1145/2897824.2925899' apa: 'Da, F., Hahn, D., Batty, C., Wojtan, C., & Grinspun, E. (2016). Surface only liquids (Vol. 35). Presented at the ACM SIGGRAPH, Anaheim, CA, USA: ACM. https://doi.org/10.1145/2897824.2925899' chicago: Da, Fang, David Hahn, Christopher Batty, Chris Wojtan, and Eitan Grinspun. “Surface Only Liquids,” Vol. 35. ACM, 2016. https://doi.org/10.1145/2897824.2925899. ieee: F. Da, D. Hahn, C. Batty, C. Wojtan, and E. Grinspun, “Surface only liquids,” presented at the ACM SIGGRAPH, Anaheim, CA, USA, 2016, vol. 35, no. 4. ista: Da F, Hahn D, Batty C, Wojtan C, Grinspun E. 2016. Surface only liquids. ACM SIGGRAPH, ACM Transactions on Graphics, vol. 35, a78. mla: Da, Fang, et al. Surface Only Liquids. Vol. 35, no. 4, a78, ACM, 2016, doi:10.1145/2897824.2925899. short: F. Da, D. Hahn, C. Batty, C. Wojtan, E. Grinspun, in:, ACM, 2016. conference: end_date: 2016-07-28 location: Anaheim, CA, USA name: ACM SIGGRAPH start_date: 2016-07-24 date_created: 2018-12-11T11:51:35Z date_published: 2016-07-11T00:00:00Z date_updated: 2023-02-21T10:36:07Z day: '11' ddc: - '000' department: - _id: ChWo doi: 10.1145/2897824.2925899 ec_funded: 1 file: - access_level: open_access checksum: 6d662893bd447d4f575b4961a2247811 content_type: application/pdf creator: system date_created: 2018-12-12T10:08:01Z date_updated: 2020-07-14T12:44:46Z file_id: '4660' file_name: IST-2016-637-v1+1_2016_Da_SOL.pdf file_size: 10561865 relation: main_file file_date_updated: 2020-07-14T12:44:46Z has_accepted_license: '1' intvolume: ' 35' issue: '4' language: - iso: eng month: '07' oa: 1 oa_version: Published Version project: - _id: 2533E772-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '638176' name: Efficient Simulation of Natural Phenomena at Extremely Large Scales publication_status: published publisher: ACM publist_id: '5881' pubrep_id: '637' quality_controlled: '1' scopus_import: 1 status: public title: Surface only liquids type: conference user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87 volume: 35 year: '2016' ... --- _id: '1362' abstract: - lang: eng text: We present a boundary element based method for fast simulation of brittle fracture. By introducing simplifying assumptions that allow us to quickly estimate stress intensities and opening displacements during crack propagation, we build a fracture algorithm where the cost of each time step scales linearly with the length of the crackfront. The transition from a full boundary element method to our faster variant is possible at the beginning of any time step. This allows us to build a hybrid method, which uses the expensive but more accurate BEM while the number of degrees of freedom is low, and uses the fast method once that number exceeds a given threshold as the crack geometry becomes more complicated. Furthermore, we integrate this fracture simulation with a standard rigid-body solver. Our rigid-body coupling solves a Neumann boundary value problem by carefully separating translational, rotational and deformational components of the collision forces and then applying a Tikhonov regularizer to the resulting linear system. We show that our method produces physically reasonable results in standard test cases and is capable of dealing with complex scenes faster than previous finite- or boundary element approaches. alternative_title: - ACM Transactions on Graphics article_number: '104' author: - first_name: David full_name: Hahn, David id: 357A6A66-F248-11E8-B48F-1D18A9856A87 last_name: Hahn - first_name: Christopher J full_name: Wojtan, Christopher J id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87 last_name: Wojtan orcid: 0000-0001-6646-5546 citation: ama: 'Hahn D, Wojtan C. Fast approximations for boundary element based brittle fracture simulation. In: Vol 35. ACM; 2016. doi:10.1145/2897824.2925902' apa: 'Hahn, D., & Wojtan, C. (2016). Fast approximations for boundary element based brittle fracture simulation (Vol. 35). Presented at the ACM SIGGRAPH, Anaheim, CA, USA: ACM. https://doi.org/10.1145/2897824.2925902' chicago: Hahn, David, and Chris Wojtan. “Fast Approximations for Boundary Element Based Brittle Fracture Simulation,” Vol. 35. ACM, 2016. https://doi.org/10.1145/2897824.2925902. ieee: D. Hahn and C. Wojtan, “Fast approximations for boundary element based brittle fracture simulation,” presented at the ACM SIGGRAPH, Anaheim, CA, USA, 2016, vol. 35, no. 4. ista: Hahn D, Wojtan C. 2016. Fast approximations for boundary element based brittle fracture simulation. ACM SIGGRAPH, ACM Transactions on Graphics, vol. 35, 104. mla: Hahn, David, and Chris Wojtan. Fast Approximations for Boundary Element Based Brittle Fracture Simulation. Vol. 35, no. 4, 104, ACM, 2016, doi:10.1145/2897824.2925902. short: D. Hahn, C. Wojtan, in:, ACM, 2016. conference: end_date: 2016-07-28 location: Anaheim, CA, USA name: ACM SIGGRAPH start_date: 2016-07-24 date_created: 2018-12-11T11:51:35Z date_published: 2016-07-01T00:00:00Z date_updated: 2023-09-07T12:02:56Z day: '01' ddc: - '000' department: - _id: ChWo doi: 10.1145/2897824.2925902 ec_funded: 1 file: - access_level: open_access checksum: 943712d9c9dc8bb5048d4adc561d7d38 content_type: application/pdf creator: system date_created: 2018-12-12T10:15:04Z date_updated: 2020-07-14T12:44:46Z file_id: '5121' file_name: IST-2016-632-v1+2_a104-hahn.pdf file_size: 12453704 relation: main_file file_date_updated: 2020-07-14T12:44:46Z has_accepted_license: '1' intvolume: ' 35' issue: '4' language: - iso: eng month: '07' oa: 1 oa_version: Published Version project: - _id: 2533E772-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '638176' name: Efficient Simulation of Natural Phenomena at Extremely Large Scales publication_status: published publisher: ACM publist_id: '5880' pubrep_id: '632' quality_controlled: '1' related_material: record: - id: '839' relation: dissertation_contains status: public status: public title: Fast approximations for boundary element based brittle fracture simulation tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: conference user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87 volume: 35 year: '2016' ... --- _id: '1633' abstract: - lang: eng text: "We present a method for simulating brittle fracture under the assumptions of quasi-static linear elastic fracture mechanics (LEFM). Using the boundary element method (BEM) and Lagrangian crack-fronts, we produce highly detailed fracture surfaces. The computational cost of the BEM is alleviated by using a low-resolution mesh and interpolating the resulting stress intensity factors when propagating the high-resolution crack-front.\r\n\r\nOur system produces physics-based fracture surfaces with high spatial and temporal resolution, taking spatial variation of material toughness and/or strength into account. It also allows for crack initiation to be handled separately from crack propagation, which is not only more reasonable from a physics perspective, but can also be used to control the simulation.\r\n\r\nSeparating the resolution of the crack-front from the resolution of the computational mesh increases the efficiency and therefore the amount of visual detail on the resulting fracture surfaces. The BEM also allows us to re-use previously computed blocks of the system matrix." article_number: '151' author: - first_name: David full_name: Hahn, David id: 357A6A66-F248-11E8-B48F-1D18A9856A87 last_name: Hahn - first_name: Christopher J full_name: Wojtan, Christopher J id: 3C61F1D2-F248-11E8-B48F-1D18A9856A87 last_name: Wojtan orcid: 0000-0001-6646-5546 citation: ama: 'Hahn D, Wojtan C. High-resolution brittle fracture simulation with boundary elements. In: Vol 34. ACM; 2015. doi:10.1145/2766896' apa: 'Hahn, D., & Wojtan, C. (2015). High-resolution brittle fracture simulation with boundary elements (Vol. 34). Presented at the SIGGRAPH: Special Interest Group on Computer Graphics and Interactive Techniques, Los Angeles, CA, United States: ACM. https://doi.org/10.1145/2766896' chicago: Hahn, David, and Chris Wojtan. “High-Resolution Brittle Fracture Simulation with Boundary Elements,” Vol. 34. ACM, 2015. https://doi.org/10.1145/2766896. ieee: 'D. Hahn and C. Wojtan, “High-resolution brittle fracture simulation with boundary elements,” presented at the SIGGRAPH: Special Interest Group on Computer Graphics and Interactive Techniques, Los Angeles, CA, United States, 2015, vol. 34, no. 4.' ista: 'Hahn D, Wojtan C. 2015. High-resolution brittle fracture simulation with boundary elements. SIGGRAPH: Special Interest Group on Computer Graphics and Interactive Techniques vol. 34, 151.' mla: Hahn, David, and Chris Wojtan. High-Resolution Brittle Fracture Simulation with Boundary Elements. Vol. 34, no. 4, 151, ACM, 2015, doi:10.1145/2766896. short: D. Hahn, C. Wojtan, in:, ACM, 2015. conference: end_date: 2015-08-13 location: Los Angeles, CA, United States name: 'SIGGRAPH: Special Interest Group on Computer Graphics and Interactive Techniques' start_date: 2015-08-09 date_created: 2018-12-11T11:53:09Z date_published: 2015-07-27T00:00:00Z date_updated: 2023-09-07T12:02:56Z day: '27' ddc: - '000' department: - _id: ChWo doi: 10.1145/2766896 ec_funded: 1 file: - access_level: open_access checksum: 955aee971983f6b6152bcc1c9b4a7c20 content_type: application/pdf creator: system date_created: 2018-12-12T10:15:13Z date_updated: 2020-07-14T12:45:07Z file_id: '5131' file_name: IST-2016-609-v1+1_FractureBEM.pdf file_size: 20154270 relation: main_file file_date_updated: 2020-07-14T12:45:07Z has_accepted_license: '1' intvolume: ' 34' issue: '4' language: - iso: eng month: '07' oa: 1 oa_version: Submitted Version project: - _id: 2533E772-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '638176' name: Efficient Simulation of Natural Phenomena at Extremely Large Scales publication_status: published publisher: ACM publist_id: '5522' pubrep_id: '609' quality_controlled: '1' related_material: record: - id: '839' relation: dissertation_contains status: public scopus_import: 1 status: public title: High-resolution brittle fracture simulation with boundary elements type: conference user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 34 year: '2015' ...