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Failure prediction of steel components under the coupled effect of excessive plastic deformations and pitting corrosion

Mohammad Ali Mahdavipour of the Faculty of Engineering and Science at the University of Agder has submitted his thesis entitled «Failure prediction of steel components under the coupled effect of excessive plastic deformations and pitting corrosion» and will defend the thesis for the PhD-degree Monday 23 May 2022. (Photo: Private)

In general, this thesis provides a developmental path from a material to a component scale to establish a failure assessment framework and to push different aspects of it towards the final application that is predicting the effect of pitting corrosion in steel structures under extreme loads.

Mohammad Ali Mahdavipour

PhD Candidate

Mohammad Ali Mahdavipour of the Faculty of Engineering and Science at the University of Agder has submitted his thesis entitled «Failure prediction of steel components under the coupled effect of excessive plastic deformations and pitting corrosion» Monday 23 May 2022.

He has followed the PhD-programme at the Faculty of Engineering and Science at the University of Agder with specialisation in Engineering Sciences, Scientific field Civil and Structural Engineering.

Summary of the thesis by Mohammad Ali Mahdavipour:

Failure prediction of steel components under the coupled effect of excessive plastic deformations and pitting corrosion

Nowadays, modern computers have made advanced computational resources accessible to analysts engaged in the field of structural engineering.

Through these advancements, the role of numerical modeling has increasingly become more significant in both research and engineering projects.

In addition, improved testing facilities and measuring instruments like digital image correlation (DIC) have made material testing more informative than before, and engineers can calibrate more complicated material models to simulate complex phenomena such as plasticity and fracture.

Testing and modeling

All developed testing and numerical modeling techniques come together to form a numerical failure assessment framework for steel structures.

Due to the distinct advantages of numerical modeling over full-scale testing, this framework is well-developed in many applications (e.g., elastic analyses).

However, in many other applications, numerous involved phenomena and their interactions with each other, as well as additional factors (e.g., corrosion), call for more development both in material testing and numerical techniques to customize the framework to better suit the final application.

An alternative approach

This thesis has focused on the failure assessment of steel components under the coupled effect of extensive plasticity and pitting corrosion. A framework was developed based on experimental material calibration and stochastic numerical modeling approaches.

To establish the assessment framework, this thesis has investigated material scale by proposing and validating an alternative approach to calibrate ductile fracture criterion based on the DIC technique.

The proposed method makes calibration feasible for welding and heat-affected zones and mitigates the inaccuracies typically associated with the common calibration process.

Corrosion uncertainties

In addition, the failure of practical steel members with pitting corrosion under excessive plastic deformations was predicted on the component scale by considering the pitting corrosion uncertainties. For this purpose, the corrosion uncertainties were explicitly involved in developing the concept of fracture-based fragility curves at the component level.

In this connection, a mesh carving technique with distinct features was introduced and validated to implement the random pitting morphologies into numerical models.

The proposed fragility curves resulting from the failure assessment framework can address the effect of pitting corrosion in terms of the probability of failure, which is an important parameter for the risk-based corrosion management in steel structures located in corrosive environments.

Furthermore, the localized material behavior due to pitting corrosion was efficiently linked to component scales.

For this purpose, relevant challenges and proper solutions were discussed in terms of applying the micromechanics-based modeling to a large-scale and complicated geometry, e.g., a steel beam-to-column joint.

In this connection, two-level numerical modeling was proposed as a solution to reduce the complexity of the problem for a practical structural application.

A development path

In general, this thesis provides a developmental path from a material to a component scale to establish a failure assessment framework and to push different aspects of it towards the final application that is predicting the effect of pitting corrosion in steel structures under extreme loads.

Based on the outcomes of such a framework, decision-makers can utilize risk management methods and assess the most critical scenarios in terms of principal criteria, e.g., health and safety, economy, and environment, and accordingly update protection and retrofit plans to extend the lifetime of steel structures.

Disputation facts:

The trial lecture and the public defence will take place on campus in Auditorium C2 040, Campus Grimstad, and online (registration link below) via the Zoom conferencing app - registration link below.

Vice Dean Rein Terje Thorstensen, Faculty of Engineering and Science, University of Agder, will chair the disputation.

The trial lecture Monday 23 May at 10:15 hours
Public defense Monday 23 May at 12:15 hours

 

Given topic for trial lecture«Design of steel structures in a sustainable future»

Thesis Title«Failure prediction of steel components under the coupled effect of excessive plastic deformations and pitting corrosion»

Search for the thesis in AURA - Agder University Research Archive, a digital archive of scientific papers, theses and dissertations from the academic staff and students at the University of Agder.

The thesis is available here:

https://uia.brage.unit.no/uia-xmlui/handle/11250/2994239

If the link does not work, you can read the thesis as a pdf:

 

The CandidateMohammad Ali Mahdavipour (1986, Shahrbabak, Iran) B.Sc. Civil Engineering, Yazd University (2010) M.Sc. Structural Engineering (Amirkabir University of Technology (2013).

Opponents:

First opponent: Professor Arild Holm Clausen, NTNU - Norwegian University of Science and Technology

Second opponent: Head of Sub-Department, Dr.-Ing. Till Clausmeyer, Technische Universität Dortmund, Germany

Associate professor Martin Choux, University of Agder, is appointed as the administrator for the assessment committee.

Supervisors in the doctoral work were Associate Professor Dmitry Vysochinskiy, University of Agder (main supervisor) and Associate Professor Zhiyu Jiang, University of Agder (co-supervisor)

Opponent ex auditorio:

The chair invites members of the public to pose questions ex auditorio in the introduction to the public defense. Deadline is during the break between the two opponents.The person asking questions should have read the thesis. The Contact Persons e-mail are available in the chat function during the Public Defense, and questions ex auditorio can be submitted to Kristine Evensen Reinfjord on e-mail kristine.reinfjord@uia.no.