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Non-uniform corrosion prediction of stiffened plates due to interactions with mechanical stresses

Non-uniform corrosion prediction of stiffened plates due to interactions with mechanical stresses
Non-uniform corrosion prediction of stiffened plates due to interactions with mechanical stresses
Corrosion is recognised as a mechanism which significantly degrades structural integrity. For example from open literature, area coverage of 30% with through-thickness pits would reduce the ultimate collapse strength of a steel plate (800 mm x 800 mm x 15 mm) by up to 50%. By applying some counter measures, such as coatings and cathodic protection, the time before corrosion initiates and the area over which it spreads can be reduced. However, failures in the counter measures can still occur due to deformation from the structural loading or accidental damage and the corrosion inevitably will still occur. Hence an accurate prediction model to assess the corrosion behaviour is essential, to determine what corrosion is likely to occur, how this will propagate and the effect it will have on the ultimate collapse strength. To do this most corrosion prediction models rely on historical datasets taken from a small range of ships in a limited range of conditions. These models give little insight into what happens when the conditions change especially the interaction between mechanical stresses and corrosion growth, termed mechano-electrochemical induced corrosion. It is difficult to tell from the empirical models whether the data is gathered from areas of high or low stress or how much this will change the rate of corrosion growth. In this study, we included the effect of stress on a Weibull function, and this stress factor is based on electrochemical measurements taken from open literature. This corrosion model is then embedded into a nonlinear finite element model of a steel stiffened plate in seawater. The thickness reduction of each discretised element is assessed as a function of stress and time. The simulation results show dynamic changes in thickness reduction for each element in the corroded area which takes on a bench-shaped form, similar to what has been found in reality.
Asranet
Ilman, Eko Charnius
b0bf0c91-81e4-4314-9de0-f1efe5a92c9d
Wharton, Julian
965a38fd-d2bc-4a19-a08c-2d4e036aa96b
Wang, Yikun
2729f2f1-36d7-4daa-8589-b61fcc99a313
Sobey, Adam
e850606f-aa79-4c99-8682-2cfffda3cd28
Ilman, Eko Charnius
b0bf0c91-81e4-4314-9de0-f1efe5a92c9d
Wharton, Julian
965a38fd-d2bc-4a19-a08c-2d4e036aa96b
Wang, Yikun
2729f2f1-36d7-4daa-8589-b61fcc99a313
Sobey, Adam
e850606f-aa79-4c99-8682-2cfffda3cd28

Ilman, Eko Charnius, Wharton, Julian, Wang, Yikun and Sobey, Adam (2018) Non-uniform corrosion prediction of stiffened plates due to interactions with mechanical stresses. In 1st International Conference on Structural Integrity for Offshore Energy Industry. Asranet..

Record type: Conference or Workshop Item (Paper)

Abstract

Corrosion is recognised as a mechanism which significantly degrades structural integrity. For example from open literature, area coverage of 30% with through-thickness pits would reduce the ultimate collapse strength of a steel plate (800 mm x 800 mm x 15 mm) by up to 50%. By applying some counter measures, such as coatings and cathodic protection, the time before corrosion initiates and the area over which it spreads can be reduced. However, failures in the counter measures can still occur due to deformation from the structural loading or accidental damage and the corrosion inevitably will still occur. Hence an accurate prediction model to assess the corrosion behaviour is essential, to determine what corrosion is likely to occur, how this will propagate and the effect it will have on the ultimate collapse strength. To do this most corrosion prediction models rely on historical datasets taken from a small range of ships in a limited range of conditions. These models give little insight into what happens when the conditions change especially the interaction between mechanical stresses and corrosion growth, termed mechano-electrochemical induced corrosion. It is difficult to tell from the empirical models whether the data is gathered from areas of high or low stress or how much this will change the rate of corrosion growth. In this study, we included the effect of stress on a Weibull function, and this stress factor is based on electrochemical measurements taken from open literature. This corrosion model is then embedded into a nonlinear finite element model of a steel stiffened plate in seawater. The thickness reduction of each discretised element is assessed as a function of stress and time. The simulation results show dynamic changes in thickness reduction for each element in the corroded area which takes on a bench-shaped form, similar to what has been found in reality.

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Published date: 7 September 2018

Identifiers

Local EPrints ID: 423698
URI: http://eprints.soton.ac.uk/id/eprint/423698
PURE UUID: 5ca9b77e-f534-44a6-a81e-839365f2c902
ORCID for Eko Charnius Ilman: ORCID iD orcid.org/0000-0002-9011-7733
ORCID for Julian Wharton: ORCID iD orcid.org/0000-0002-3439-017X
ORCID for Yikun Wang: ORCID iD orcid.org/0000-0001-5619-7795
ORCID for Adam Sobey: ORCID iD orcid.org/0000-0001-6880-8338

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Date deposited: 27 Sep 2018 16:30
Last modified: 08 May 2020 00:38

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