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Martínez, Edel R.

University of British Columbia

This thesis aims at understanding the lifetime of stress corrosion cracks of underground pipelines in contact with solutions of near-neutral pH. While hydrogen-induced cracking of disbonded coated pipelines has been recognized as the driving corrosion mechanism for more than three decades, its impact on the lifetime of cracks has yet to be found. To address this, multiphysics and stochastic finite element models were developed to predict the behavior of stress corrosion cracking under multiple conditions. A first physics-based model was formulated within the framework of the phase field paradigm. It couples the effects of hydrogen embrittlement in the crack initiation and early growth of the colonies. The effects of mechanical stress and colony morphology on redistribution and equilibrium of hydrogen concentration in three dimensions were studied. A second physics-based model predicted the role of hydrogen embrittlement and hydrogen-assisted anodic dissolution on the stable crack growth range. This investigation used a material model that simulates the effects of hydrogen-enhanced localized plasticity. The proposed approach was validated against published laboratory measurements in a full-scale pipe test, where the two distinct crack propagation models were used and compared. Corrosion fatigue lifetimes were better predicted exclusively using the hydrogen embrittlement mechanism. Further, the combined effects of corrosion localization and cracks have been modeled under various electro-chemo-mechanical conditions through sensitivity analysis. The robust combination of physics-based and uncertainty shed light on the lifetime of near-neutral pH stress corrosion crack growth. Physics and statistical modeling results showed tremendous potential to replace expensive and time-consuming experimental programs with simulations.

Text

2023-01-05

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83595

Civil Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/