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"Jimmie" Hamilton Award

 

Dr. Bilal M. Ayyub



"Jimmie" Hamilton Award 

2003; 2002 

Dr. Unyime O. Akpan, Dr. Tamunoiyala S. Koko, Dr. Bilal M. Ayyub, and Timothy E. Dunbar (2003); Dr. Bilal M. Ayyub, Dr. Ibrahim A. Assakkaf, Dr. David P. Kihl, and Mr. Michael W. Sieve (2002); Dr. Gilberto F.M. de Souza and Dr. Bilal Ayyub, P.E. (2000)

For the best original paper published in the Naval Engineers Journal during the years 2003, 2002 and 2000 as set forth in the following:

 
Dr. John C. Daidola and RADM David P. Sargent present the "Jimmie" Hamilton Award to Dr. Ayyub (2003)


2003:
The paper "Reliability Assessment of Corroding Ship Hull Structure" was published in the Naval Engineers Journal, Fall 2003 edition. The authors have developed an approach for time-dependent reliability assessment of the ultimate strength of a ship hull structure in the presence of corrosion. By modeling corrosion growth as a time-dependent random function and using the second order reliability method to calculate the instantaneous reliability of the primary hull structure, they demonstrated that the proposed time-dependent reliability is always lower than the instantaneous reliability and more sensitive to the statistical value of the corrosion parameters than their probabilistic distribution descriptions. Time-dependent reliability results provide the basis for computing hazard functions and subsequent decisions relating to life expectancy analysis and extension.

The authors have demonstrated the proposed method using a typical cross section of a tanker including parametric analysis.

This paper captures the essence of time-dependent reliability-based analysis of ship structures subject to corrosion, and provides a basis for including corrosion in reliability studies in order to obtain realistic estimates. It is definitely in keeping with the technical standards of the Naval Engineers Journal. The authors are most deserving of the Society's 2003 "Jimmie" Hamilton Award.

 

2002:
RADM Paul E. Sullivan, USN, presents the "Jimmie" Hamilton Award to Dr. AyyubThe paper "Reliability-Design Guidelines for Fatigue of Ship Structures" was published in the Naval Engineers Journal of Spring 2002. The authors have developed reliability-based methods for determining the fatigue life of structural details associated with conventional displacement-type, surface monohull ships based on the maximum stress to cycles-to-failure ratio (S-N curve) approach. The methods are also based on structural reliability theory and can be applied either in direct reliability-based design or in a load and resistance factor design (LRFD) format. The LRFD methods were developed according to spectral analysis of wave loads, building on conventional codes, nominal strength and load values, and achieving target reliability levels. The first-order reliability method (FORM) was used to develop the partial safety factors for selected fatigue limit state equations and for demonstration purposes.

This paper stands not only on its own merits but is also representative of the eight quality papers of the spring 2002 special issue on reliability-based design of naval ship structures using LRFD. These papers were the culmination of work begun in the early 1980s by NSWCCD and the University of Maryland and subsequent program management provided by NAVSEA.

This paper captures the essence of the analytical and experimental work done in the development of this design methodology. It is definitely in keeping with the technical standards of the Naval Engineers Journal. The authors are most deserving of the Society's 2002 "Jimmie" Hamilton Award.

 

2000:
The paper, "Probabilistic Fatigue Life Prediction for Ship Structures Using Fracture Mechanics," was presented at the ASNE Day 2000 Annual Meeting and Exposition on May 19, 2000, and published in the Naval Engineers Journal of July 2000. This paper discusses and demonstrates the use of probabilistic linear elastic fracture mechanics to model fatigue of ship structure. Probabilistic analysis requires the use of reliability methods for assessing fatigue life by considering the crack propagation process and the uncertainties associated with it. As an improvement to the traditional probabilistic fatigue fracture approach, this paper presents a methodology for probabilistic analysis of ship structure fatigue failure considering the effects of the residual stresses induced by the hull fabrication process over the crack growth rate.

The application of Drs. de Souza and Ayyub's methodology can be viewed as a significant first step toward the ultimate goal of developing reliability-based design rules for ship structural fatigue based on fracture mechanics.

In developing and demonstrating this highly valuable methodology, the authors have made an important and lasting contribution to the naval engineering profession, and are worthy to receive the Society's 2000 "Jimmie" Hamilton Award, in keeping with the highest ideals of the Naval Engineers Journal.

 

1992:
The paper, "Structural Reliability Assessment with Ambiguity and Vagueness in Failure" in the May 1992 issue of the Naval Engineers Journal is a significant contribution to the literature in the field of naval engineering.  It easily meets all the selection criteria, particularly in its originality and quality of presentation, making it worthy of recognition by the Society.

The application of vagueness to structural failure through the use of fuzzy sets and systems has the potential for significantly enhancing structural reliability methods.  The authors have developed methodology using this approach that establishes a sound foundation for further development and adaptation to the naval engineering environment.

In promoting the advancement of the state-of-the-art through its complete, well structured presentation, this paper epitomizes the mission of the Society and the Naval Engineers Journal.  It constitutes a definite contribution to the naval engineering profession and to its literature and is indeed worthy to receive the 1992 "Jimmie" Hamilton Award.

 

 
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