PSI - Issue 28

ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceD rect Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 28 (2020) 2072–2077

© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo Abstract We have been studying the collective, global behaviour of multiple cracks in solid materials and its connection with each individual, local crack motion. Here, by using a high-speed digital video camera, we examine fracture evolution in a two-dimensional, initially linear elastic rectangular polycarbonate specimen where sets of cracks are prepared and uniaxial tensile strain with a prescribed constant rate is externally applied. We trace local fracture development around every individual crack, and simultaneously, we obtain global stress-strain curves and physical properties like tensile strength of the specimens. By knowing the global characteristics, then, we concentrate our attention to more local, secondary and further fractures caused by the extending main or primary fracture and reversely its influence on the global nature of the multiply cracked specimens. For various different distribution patterns and values of density of initial cracks, we observe the dynamic evolution of the primary fracture and the fracture-induced waves, as well as the generation of the subsidiary fracture. We find that after a total split of the specimen into two by the propagation of the primary fracture, the secondary fracture may be initiated and propagated at a distance from the primary fracture. That is, fracture propagation may jump in multiply cracked solids even without additional external loading. Moreover, in our observations, the secondary fracture moves into the direction opposite to the primary one, and is once arrested and then resumes its propagation with some delay. The secondary and further fractures, or a cluster of fractures, are obviously not owing to additional external energy, but by dynamic waves produced upon enlargement of the primary fracture. The development of the secondary and further fractures in a specimen may be concealed in the global stress-strain relation but may rather appear in a global pattern of dynamic wave radiation such as doublet or a cluster of ruptures in the solid Earth, namely, earthquakes. © 2020 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo Keywords: collective behaviour; local motion, fracture jumping; fracture reactivation, wave-induced fracture Abstract We have been studying the collective, global behaviour of multiple cracks in solid materials and its connection with each individual, local crack motion. Here, by using a hi h-speed digital video cam ra, we examine fr cture evolu ion in a tw -dimensional, initially inear elastic rectangular polycarbonate specimen where sets of c cks are prepared and uniaxial te sile strain with a prescr bed constant rate is extern lly applied. We trace local fractur development around every individu l crack, and simultaneou ly, we obtain global stress-strain curves and physical p operties like tensile strength of the specimens. By knowing the global characteristics, th n, we con entrate our attention to more local, seco dary and further fractur s caused by the exte ding main or prim ry fra ture a d reversely its influence the global nature of the multiply cracked specimens. For various different distribution patt rns and values of density of initial cracks, we observe the dynamic evolution of th prima y fract re and the fracture-induced waves, as well as the generatio of the sub idiary fracture. We find that after a total split of the specimen into two by the propagation of the primary fracture, the secondary fractu e m y b initiated and propagated at a distance from the primary fracture. Th t is, fractur ropagation may jump in multiply cracked solids even without additional external loading. Moreover, in our observations, the secondary fracture moves into the direction opposite to th primary one, and is onc arreste and then resumes its propagation wit some dela . The s condary and further fractures, or a clust r of fr ctures, re obviously not owi g to additional exte nal energy, but by dynamic waves pro uced upon enlargement of the primary fracture. The devel pme t of the secon ary a d further fractures in a specimen may be c ncealed in the global stress-strain relation b t may rather a pear in a global pattern of dynamic wave radiation such as doubl t r a cluster of ruptures in the solid Earth, namely, earthquakes. © 2020 The Authors. Publis ed by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of European Structural Integri y Soci ty (ESIS) ExCo Keywords: collective behaviour; local motion, fracture jumping; fracture reactivation, wave-induced fracture 1st Virtual European Conference on Fracture Dynamic fracture development in a multiply cracked solid Koji Uenishi a,b *, Yuki Fukuda b , Kunihiro Nagasawa b a Department of Advanced Energy, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8561, Japan b Department of Aeronautics and Astronautics, The University of Tokyo, 7-3-1 Hongo, Bunkyo 113-8656, Japan 1st Virtual European Conference on Fracture Dynamic fracture development in a multiply cracked solid Koji Uenishi a,b *, Yuki Fukuda b , Kunihiro Nagasawa b a Department of Advanced Energy, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8561, Japan b Department of Aeronautics and Astronautics, The University of Tokyo, 7-3-1 Hongo, Bunkyo 113-8656, Japan

* Corresponding author. Tel.: +81-4-7136-3824; fax: +81-4-7136-3824. E-mail address: uenishi@k.u-tokyo.ac.jp * Corresponding author. Tel.: +81-4-7136-3824; fax: +81-4-7136-3824. E-mail address: uenishi@k.u-tokyo.ac.jp

2452-3216 © 2020 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo 2452-3216 © 2020 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo 10.1016/j.prostr.2020.11.031