PSI - Issue 39

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 39 (2022) 222–228

© 2021 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 CP 2021 – Guest Editors In this work, an attempt has been made out to understand the micro-fracture scale effect on the crack growth rate in concrete material under the action of fatigue loading. A theoretical model has been developed based on atomic fracture mechanics theory. Using the concept, the activation energy controls the random movement of the nano-crack front in the subcritical environment of micro-crack growth within the cyclic fracture process zone of quasi-brittle material. Kramer's formula has been used for the prediction of net frequency of the forward crack front jumps by assuming, fatigue crack propagation rate is governed by thermally activated breakage of interatomic bonds. A multi-scale transition approach has been adopted from micro to the macro using scaling law considering energy dissipation in each cycle to grow a macro-crack is equal to the sum of the energy dissipations associated with the propagation of all the active micro-cracks inside the cyclic fracture process zone. © 2021 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 CP 2021 – Guest Editors Keywords: Fracture process zone ; loading frequency ; micro crack ; nano mechanics ; scaling laws ; size effect Abstract Developments of scaling laws are crucially important for modeling an engineering phenomenon. Based on the type of physical problems scaling laws have been developed in conjunction with the concept of self-similarity. Scale effect should take into account when the size of an object reduces to extremely small-scale level. Therefore, scaling/power laws and similarity concepts have been considered to be important in nano mechanics in the recent times. In the case of quasi-brittle materials like concrete, crack growth phenomenon can considered as a multi-scale problem comprising of atomistic separation, nano scale level coalesce to form micro and subsequently, major crack. Therefore, it is necessary to have a clear understanding of cracking phenomenon in concrete at different length scales under the action of repetitive loading cycles. In this work, an attempt has been made out to understand the micro-fracture scale effect on the crack growth rate in concrete material under the action of fatigue loading. A theoretical model has been developed based on atomic fracture mechanics theory. Using the concept, the activation energy controls the random movement of the nano-crack front in the subcritical environment of micro-crack growth within the cyclic fracture process zone of quasi-brittle material. Kramer's formula has been used for the prediction of net frequency of the forward crack front jumps by assuming, fatigue crack propagation rate is governed by thermally activated breakage of interatomic bonds. A multi-scale transition approach has been adopted from micro to the macro using scaling law considering energy dissipation in each cycle to grow a macro-crack is equal to the sum of the energy dissipations associated with the propagation of all the active micro-cracks inside the cyclic fracture process zone. © 2021 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 CP 2021 – Guest Editors Keywords: Fracture process zone ; loading frequency ; micro crack ; nano mechanics ; scaling laws ; size effect 7th International Conference on Crack Paths Nano-mechanics based crack growth characterization of concrete under fatigue loading Bineet Kumar a, * , Sonalisa Ray b 7th International Conference on Crack Paths Nano-mechanics based crack growth characterization of concrete under fatigue loading Bineet Kumar a, * , Sonalisa Ray b a Research scholar, Indian Institute of Technology, Roorkee, 247667, India b Associate professor, Indian Institute of Technology, Roorkee, 247667, India a Research scholar, Indian Institute of Technology, Roorkee, 247667, India b Associate professor, Indian Institute of Technology, Roorkee, 247667, India Abstract Developments of scaling laws are crucially important for modeling an engineering phenomenon. Based on the type of physical problems scaling laws have been developed in conjunction with the concept of self-similarity. Scale effect should take into account when the size of an object reduces to extremely small-scale level. Therefore, scaling/power laws and similarity concepts have been considered to be important in nano mechanics in the recent times. In the case of quasi-brittle materials like concrete, crack growth phenomenon can considered as a multi-scale problem comprising of atomistic separation, nano scale level coalesce to form micro and subsequently, major crack. Therefore, it is necessary to have a clear understanding of cracking phenomenon in concrete at different length scales under the action of repetitive loading cycles.

* Corresponding author. E-mail address: India-bkumar2@ce.iitr.ac.in * Corresponding author. E-mail address: India-bkumar2@ce.iitr.ac.in

2452-3216 © 2021 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 CP 2021 – Guest Editors 2452-3216 © 2021 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 CP 2021 – Guest Editors

2452-3216 © 2021 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 CP 2021 – Guest Editors 10.1016/j.prostr.2022.03.091