Youssef Hafiz


In the current research, a new assessment procedure is proposed to determine the shakedown limit load of locally thinned wall pressurized components via modifying the current API 579 level-three assessment. The new assessment procedure applies a well-established and verified simplified technique, previously developed by Abdalla et al. [1], discarding iterative full elastic-plastic cyclic loading finite element (FE) analyses. For the purpose of validation, the newly proposed assessment procedure is applied to generate the shakedown boundary of a locally thinned wall pipe-branch connection subjected to a spectrum of steady internal pressures and cyclic bending moments. The outcomes of the proposed assessment procedure are successfully verified against existing API 579 assessment procedures, numerical analyses, and experimental outcomes taken from the literature. Interaction (Bree) diagrams illustrating elastic, shakedown, and limit load domains are constructed for the locally thinned wall pipe-branch connection problem. Additionally, a parametric study is performed through changing the both the depth and location of the local wall thinning within the pipe-branch connection. The outcomes of the parametric study show good agreement in the shakedown limit boundary results with the API 579 elastic-plastic stress analysis procedure.


Mechanical Engineering Department

Degree Name

MS in Mechanical Engineering

Graduation Date


Submission Date

January 2013

First Advisor

Younan, Maher

Committee Member 1

Abdalla, Hany


91 p.

Document Type

Master's Thesis

Library of Congress Subject Heading 1

Pumping machinery -- Evaluation.

Library of Congress Subject Heading 2



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Institutional Review Board (IRB) Approval

Not necessary for this item


â Feeling gratitude and not expressing it is like wrapping a present and not giving itâ . My great and first present is wrapped for Allah. Allah granted me power, patience and ability to accomplish what it was seemed to be impossible for me. Second great present is wrapped with appreciation and thanks to my supervisor Dr. Maher Youn. He was a father who taught me things that I cannot count. Even if, he was too busy in the work load upon him, he was almost available every day for me to give advice and help in research, career and life. Third great present is wrapped for my big brother before being my co-supervisor, Dr. Hany Fayek for his effort to help and support me in all master times. A special present is wrapped to thank my parents, brothers, Mohamed and Ibrahim, and my sisters, Mo and Mariam, for their support to accomplish all my achievements in my life. â Journey best measured in friends rather than milesâ during my master program, I was extremely lucky to have a journey friend like Mostafa Siam who shares me every up and down time. Also, I would like to give special thanks to all my colleagues, especially Mohammed Abd El-Aal and Ahmed Gaber. I would also to extend my thanks to mechanical department faculty and colleagues in the American University in Cairo. Iâ m particularly grateful for accepting me in the fellowship by the American University in Cairo, mechanical engineering department and for the research grant and facilities offered for the master program.