PSI - Issue 33

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000 il l li t . i i t. tr t r l I t rit r i ( )

www.elsevier.com/locate/procedia . l i r. /l t / r i

ScienceDirect

Procedia Structural Integrity 33 (2021) 456–464

© 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 the scientific committee of the IGF ExCo Abstract Two nonlocal approaches are applied to the borehole geometry, i.e. a circular hole in an infinite elastic medium subjected to internal pressure. The former approach lays in the framework of Gradient Elasticity (GE), which results nonlocal in the strict sense, being based on a nonlocal constitutive relationship. Changing the stress field as the geometry (i.e., the radius of the hole) varies, the related stress concentration factor can be thought as the critical failure parameter. The latter approach is the Finite Fracture Mechanics (FFM), well-consolidated in the framework of brittle fracture. Whereas the model belongs to classical linear elasticity, it reveals nonlocal in a loose sense: the failure condition is no more punctual, but achieved when two average requirements on the stress and the energy ahead of the notch tip are simultaneously fulfilled. Τhe two approaches, although different, present some similarities, both involving a characteristic length. It will be shown that the GE and FFM predictions are in excellent agreement when the two lengths are properly defined. © 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 Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo Keywords: pressurized hole; crack initiation; Gradient Elasticity; Finite Fracture Mechanics 1. Introduction Higher order theories in elasticity have been proposed in order to account for the effect of microstructure (i.e. flaws, cavities, holes, grain interfaces, inclusions, etc.) and to solve various problems for deformation and fracture l l li t t l t , i. . i l l i i i it l ti i j t t i t l . l i t i t l ti it , i lt l l i t t i t , i l l tit ti l ti i . i t t i l t t i. ., t i t l i , t l t t t ti t t t t iti l il t . l tt i t i it t i , ll li t i t ittl t . t l l t l i l li l ti it , it l l l i l : t il iti i t l, t i t i t t t t t t ti i lt l l ill . t , lt i t, t i il iti , t i l i t i ti l t . t ill t t t i ti i ll t t t t l t l i . © 2021 The Authors. Published . . i i article under the CC BY-N li tt :// ti . /li / / . i t t t: i i ilit t i ti i itt t : r ri l ; r i iti ti ; r i t l ti it ; i it r t r i . i i t i i l ti it i t t t t i t t i. . l , iti , l , i i t , i l i , t . t l i l ti t IGF26 - 26th International Conference on Fracture and Structural Integrity Comparison between two nonlocal criteria: A case study on pressurized holes A. Sapora a , G. Efremidis b , P. Cornetti a * a Department of Structural Engineering and Geotechnics, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy b Department of Civil Engineering, University of Thessaly, Pedion Areos, 38334 Volos, Greece A a t t f t t l i i t i , lit i i i , li i , i , It l b t t f i il i i , i it f l , i , l ,

* Corresponding author. Tel.: +39-011-090-4901 E-mail address : pietro.cornetti@polito.it i t r. l.: - - - - il : i tr . r tti lit .it rr

-

t r .

li

I . .

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 Statement: Peer-review under responsibility of the scientific committee of the IGF ExCo i i rti l r t - - li ( tt :// r ti . r /li / - - / . ) r-r i t t t: r-r i r r i ilit f t i tifi itt f t I

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 the scientific committee of the IGF ExCo 10.1016/j.prostr.2021.10.052