PSI - Issue 39

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 ir t. i i tructural Integrity rocedia 00 (2019) 000–000

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ScienceDirect

Procedia Structural Integrity 39 (2022) 419–431

© 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 Abstract The effect of an initial mode II loading on subsequent mixed-mode crack path was investigated through experiments and computations for 34X and P2M steels, 7050 aluminum, and Ti-6Al-4V alloys in a compact tension shear (CTS) specimen. An optical microscope and the drop potential method were used to determine the actual position of the crack tip on the curvilinear crack path monitoring and continuous measurements of the crack size were made along the path in the CTS specimen. In accordance with these experimental observations, the main feature of the initial mode II fracture is the crack growth on a curvilinear path. For subsequent mixed-mode crack propagation, the crack front continuously changes the shape and direction with each loading cycle. For a mode II loaded initial crack, the scenario becomes more complex because of the change in the propagation direction when a kinked crack is formed. The experimental data on crack growth for all tested materials are represented in terms of the elastic and new plastic stress intensity factors (SIFs). To this end, both the classical and the conventional mechanism-based strain-gradient plasticity (CMSGP) theories were employed. The material constitutive equation is implemented in a finite element code and the elastic and plastic fracture resistance parameters are calculated as a function of the position along the curvilinear crack path in all tested CTS specimens produced from 34X and P2M steels, 7050 aluminum and Ti-6Al-4V alloys. As a result of the finite element calculations, nonlinear amplitude factor solutions are determined across a wide range of material work hardening conditions, and the role of the Taylor’s intrinsic material length and both the coupled effect of these parameters are established. The potential of fundamental and practical applications of introduced fracture resistance parameters are discussed. © 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: Mixed mode; strain gradient plasticity; plastic stress intensity factor; finite element analysis. e effect f a i itial e II l a i s se e t i e - e crac at as i esti ate t r e eri e ts a c tati s f r a steels, al i , a i- l- all s i a c act te si s ear ( ) s eci e . tical icr sc e a t e r te tial et ere se t eter i e t e act al siti f t e crac ti t e c r ili ear crac at it ri a c ti s eas re e ts f t e crac size ere a e al t e at i t e s eci e . I acc r a ce it t ese e eri e tal ser ati s, t e ai feat re f t e i itial e II fract re is t e crac r t a c r ili ear at . r s se e t i e - e crac r a ati , t e crac fr t c ti sl c a es t e s a e a irecti it eac l a i c cle. r a e II l a e i itial crac , t e sce ari ec es re c le eca se f t e c a e i t e r a ati irecti e a i e crac is f r e . e e eri e tal ata crac r t f r all teste aterials are re rese te i ter s f t e elastic a e lastic stress i te sit fact rs ( I s). t is e , t t e classical a t e c e ti al ec a is - ase strai - ra ie t lasticit ( ) t e ries ere e l e . e aterial c stit ti e e ati is i le e te i a fi ite ele e t c e a t e elastic a lastic fract re resista ce ara eters are calc late as a f cti f t e siti al t e c r ili ear crac at i all teste s eci e s r ce fr a steels, al i a i- l- all s. s a res lt f t e fi ite ele e t calc lati s, li ear a lit e fact r s l ti s are eter i e acr ss a i e ra e f aterial r ar e i c iti s, a t e r le f t e a l r’s i tri sic aterial le t a t t e c le effect f t ese ara eters are esta lis e . e te tial f f a e tal a ractical a licati s f i tr ce fract re resista ce ara eters are isc sse . © e t rs. Publis e by ELSEVIER B.V. This is an open access article er t e - - lice se ( tt s://creati ec s. r /lice ses/ - c- / . ) eer-re ie er res si ilit f est it rs ey ords: ixed ode; strain gradient plasticity; plastic stress intensity factor; finite ele ent analysis. 7th International Conference on Crack Paths Mixed mode crack paths in terms of plastic stress intensity factors based on conventional and strain gradient plasticity D. Fedotova a, *, R. Khamidullin a a FRC Kazan Scientific Center, Russian Academy of Sciences, Lobachevskogo st., 2/31, Kazan 420111, Russia t I t r ti l f r r t . t a, , . i lli a a azan Scientific enter, ussian cade y of Sciences, obachevskogo st., 2/31, azan 420111, ussia str ct

* Corresponding author. Tel.: +7-843-236-3102; fax: +7-843-236-3102. E-mail address: prosvirnina_95@mail.ru * orresponding author. el.: 7-843-236-3102; fax: 7-843-236-3102. - ail address: prosvirnina_95 ail.ru

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 he uthors. ublished by I . . his is an open access article under the - - license (https://creativeco ons.org/licenses/by-nc-nd/4.0) eer-revie under responsibility of 2021 – uest ditors

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.2022.03.111