New perspective of fracture mechanics inspired by gap test with crack-parallel compression
The line crack models, including linear elastic fracture mechanics (LEFM), cohesive crack model (CCM), and extended finite element method (XFEM), rest on the century-old hypothesis of constancy of materials’ fracture energy. However, the type of fracture test presented here, named the gap test, reve...
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ftpubmed:oai:pubmedcentral.nih.gov:7321980 2023-05-15T18:18:40+02:00 New perspective of fracture mechanics inspired by gap test with crack-parallel compression Nguyen, Hoang Pathirage, Madura Rezaei, Masoud Issa, Mohsen Cusatis, Gianluca Bažant, Zdeněk P. 2020-06-23 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7321980/ http://www.ncbi.nlm.nih.gov/pubmed/32518106 https://doi.org/10.1073/pnas.2005646117 en eng National Academy of Sciences http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7321980/ http://www.ncbi.nlm.nih.gov/pubmed/32518106 http://dx.doi.org/10.1073/pnas.2005646117 https://www.pnas.org/site/aboutpnas/licenses.xhtmlPublished under the PNAS license (https://www.pnas.org/site/aboutpnas/licenses.xhtml) . Proc Natl Acad Sci U S A Physical Sciences Text 2020 ftpubmed https://doi.org/10.1073/pnas.2005646117 2020-12-13T01:18:43Z The line crack models, including linear elastic fracture mechanics (LEFM), cohesive crack model (CCM), and extended finite element method (XFEM), rest on the century-old hypothesis of constancy of materials’ fracture energy. However, the type of fracture test presented here, named the gap test, reveals that, in concrete and probably all quasibrittle materials, including coarse-grained ceramics, rocks, stiff foams, fiber composites, wood, and sea ice, the effective mode I fracture energy depends strongly on the crack-parallel normal stress, in-plane or out-of-plane. This stress can double the fracture energy or reduce it to zero. Why hasn’t this been detected earlier? Because the crack-parallel stress in all standard fracture specimens is negligible, and is, anyway, unaccountable by line crack models. To simulate this phenomenon by finite elements (FE), the fracture process zone must have a finite width, and must be characterized by a realistic tensorial softening damage model whose vectorial constitutive law captures oriented mesoscale frictional slip, microcrack opening, and splitting with microbuckling. This is best accomplished by the FE crack band model which, when coupled with microplane model M7, fits the test results satisfactorily. The lattice discrete particle model also works. However, the scalar stress–displacement softening law of CCM and tensorial models with a single-parameter damage law are inadequate. The experiment is proposed as a standard. It represents a simple modification of the three-point-bend test in which both the bending and crack-parallel compression are statically determinate. Finally, a perspective of various far-reaching consequences and limitations of CCM, LEFM, and XFEM is discussed. Text Sea ice PubMed Central (PMC) Proceedings of the National Academy of Sciences 117 25 14015 14020 |
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Physical Sciences Nguyen, Hoang Pathirage, Madura Rezaei, Masoud Issa, Mohsen Cusatis, Gianluca Bažant, Zdeněk P. New perspective of fracture mechanics inspired by gap test with crack-parallel compression |
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Physical Sciences |
description |
The line crack models, including linear elastic fracture mechanics (LEFM), cohesive crack model (CCM), and extended finite element method (XFEM), rest on the century-old hypothesis of constancy of materials’ fracture energy. However, the type of fracture test presented here, named the gap test, reveals that, in concrete and probably all quasibrittle materials, including coarse-grained ceramics, rocks, stiff foams, fiber composites, wood, and sea ice, the effective mode I fracture energy depends strongly on the crack-parallel normal stress, in-plane or out-of-plane. This stress can double the fracture energy or reduce it to zero. Why hasn’t this been detected earlier? Because the crack-parallel stress in all standard fracture specimens is negligible, and is, anyway, unaccountable by line crack models. To simulate this phenomenon by finite elements (FE), the fracture process zone must have a finite width, and must be characterized by a realistic tensorial softening damage model whose vectorial constitutive law captures oriented mesoscale frictional slip, microcrack opening, and splitting with microbuckling. This is best accomplished by the FE crack band model which, when coupled with microplane model M7, fits the test results satisfactorily. The lattice discrete particle model also works. However, the scalar stress–displacement softening law of CCM and tensorial models with a single-parameter damage law are inadequate. The experiment is proposed as a standard. It represents a simple modification of the three-point-bend test in which both the bending and crack-parallel compression are statically determinate. Finally, a perspective of various far-reaching consequences and limitations of CCM, LEFM, and XFEM is discussed. |
format |
Text |
author |
Nguyen, Hoang Pathirage, Madura Rezaei, Masoud Issa, Mohsen Cusatis, Gianluca Bažant, Zdeněk P. |
author_facet |
Nguyen, Hoang Pathirage, Madura Rezaei, Masoud Issa, Mohsen Cusatis, Gianluca Bažant, Zdeněk P. |
author_sort |
Nguyen, Hoang |
title |
New perspective of fracture mechanics inspired by gap test with crack-parallel compression |
title_short |
New perspective of fracture mechanics inspired by gap test with crack-parallel compression |
title_full |
New perspective of fracture mechanics inspired by gap test with crack-parallel compression |
title_fullStr |
New perspective of fracture mechanics inspired by gap test with crack-parallel compression |
title_full_unstemmed |
New perspective of fracture mechanics inspired by gap test with crack-parallel compression |
title_sort |
new perspective of fracture mechanics inspired by gap test with crack-parallel compression |
publisher |
National Academy of Sciences |
publishDate |
2020 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7321980/ http://www.ncbi.nlm.nih.gov/pubmed/32518106 https://doi.org/10.1073/pnas.2005646117 |
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Sea ice |
genre_facet |
Sea ice |
op_source |
Proc Natl Acad Sci U S A |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7321980/ http://www.ncbi.nlm.nih.gov/pubmed/32518106 http://dx.doi.org/10.1073/pnas.2005646117 |
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https://www.pnas.org/site/aboutpnas/licenses.xhtmlPublished under the PNAS license (https://www.pnas.org/site/aboutpnas/licenses.xhtml) . |
op_doi |
https://doi.org/10.1073/pnas.2005646117 |
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Proceedings of the National Academy of Sciences |
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117 |
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25 |
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14015 |
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