PSI - Issue 14

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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ScienceDirect

Procedia Structural Integrity 14 (2019) 774–781

2nd International Conference on Structural Integrity and Exhibition 2018 Challenges in predicting crack growth in structures operating in extreme environments Ashok Saxena* Department of Mechanical Engineering, University of Arkansas, Fayetteville, USA 2nd International Conference on Structural Integrity and Exhibition 2018 Challenges in predicting crack growth in structures operating in extreme environments Ashok Saxena* Department of Mechanical Engineering, University of Arkansas, Fayetteville, USA In creep-brittle materials, where there is competition between the evolution of crack tip stress fields due to time-dependent deformation and due to environment enhanced crack growth under sustained and cyclic loading, there are no unifying concepts that are currently available to characterize crack growth. This is a major gap in technology that currently exists and prevents the use of time-dependent fracture mechanics approach to an important class of high temperature materials such as Ni base alloys, directionally solidified (DS) materials, and single crystal (SX) materials . This paper critically reviews the promising approaches, and the needs for filling this technology gap. Recommendations for future work are made. © 2018 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/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. In c eep-brittle materials, where there is ompetition betwee the evolution of rack tip stress fields due to time-dependent deformation and due to environmen enhanced crack growth under sustained and cyclic loading, th re ar no unifying concepts that are currently available to character ze crack growth. This is major gap in technology that currently exists and prevents the us of time-depend nt fracture mechanics approa h to an important class of high temper ture materials such a Ni base lloy , directio ally s lid fied (DS) materials, and single crystal (SX) materials . This p per critically reviews the promising approaches, and the needs for filling this technology gap. Recommendations for future work are made. © 2018 The Author . Published by Elsevier B.V. This is an open access article und r the CC BY-NC-ND lic nse (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. © 2019 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/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. Abstract Abstract

Keywords: cracks, fatigue, creep, Ni base alloys, welds, environment assisted cracking Keywords: cracks, fatigue, creep, Ni base alloys, welds, environment assisted cracking

1. Introduction 1. Introduction

Extreme environments are said to be present at high temperatures when creep deformation and damage is a design concern, in the presence of TMF conditions, when environment assisted crack growth occurs due to oxidation at high temperatures, or when creep-fatigue and environment interactions occur synergistically to accelerate kinetics of crack growth rates. Extreme e vironment are said to be prese t at igh temperatures wh n reep deformation and damage is a des n conc rn, in the presence of TMF conditions, when v ronment a sisted crack rowth occurs du to oxidation at high temperatur , or when creep-fatigue and environment interactions occur synergistically to accelerate kinetics of crack growth rates.

* Ashok Saxena, Tel.: +1-479-530-2425; fax: +0-000-000-0000 . E-mail address: asaxena@uark.edu * Ashok Saxena, Tel.: +1-479-530-2425; fax: +0-000-000-0000 . E-mail address: asaxena@uark.edu

2452-3216 © 2018 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/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. 2452-3216 © 2018 The Au hors. Published by Elsevier B.V. This is an open access article und r the CC BY-NC-ND lic nse (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers.

2452-3216  2019 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/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. 10.1016/j.prostr.2019.07.055