Branko Blagojević, Modeling Ship Structural Systems by Events, PhD thesis (ppt) (full, in Croatian), Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, 2005.
Summary
In the introduction of this thesis the problems of safety, reliability and uncertainty in the lifetime service of ship structures are summarized. Scientific background and engineering experience about ship structures are also presented. The introductory part is followed by description of presentation of technical objects with events, subsystems and systems of events, particularly pointing the application of such presentation to ship structures. Systems and subsystems of events are viewed according to all observable consequences important for service of ship structures. Theoretical basics of technical modeling employing the probabilistic event oriented system analysis are given. The event oriented analysis of engineering systems is presented as a synthesis of the theory of probability and the information theory. The potentials of application of the event oriented system analysis to ship structures are described. All relevant possibilities of operational states of ship structures as well as all observable ways of collapse, damage and failure of the components of ship structures (yielding, buckling, and fatigue) are taken into account. This thesis investigates redundancy and robustness of ship structures in a manner as it was not done before, using event modeling, indicating potential improvements in ship design and utilization by using redundancy and robustness as additional decision criteria. It is described how important properties of ship structures, redundancy and robustness, are expressed by conditional entropy of operational and failure subsystems of events. This thesis introduces a sequential combinatorial algorithm appropriate for numerical solution of redundancy and robustness of complex systems typical for ship structures. Several examples of technical modeling by probabilistic event oriented system analysis of components of real ship structures are presented. Those examples confirmed that the practical application of the event oriented system analysis to ship structures is possible and useful.
Keywords: event modeling, ship structures, entropy, uncertainty, robustness, redundancy
Branko, Blagojević, Fatigue Damage Assessment of Ship Structures, Master thesis (in Croatian), Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, 2000.
Summary
In this thesis a few typical procedures for fatigue strength assessment of ship structures have been compared, with approaches through nominal, hot spot and notch stress and use of S–N curves. Comparison of procedures has been performed on an example of a double hull tanker for a few critical locations at connections of side and bottom longitudinals with the transverse structure. Analysis of parameters has also been performed on one bulk carrier. All relevant parameters which influence determination of fatigue damage, have been analyzed – shape parameter of Weibull stress distribution, corrosion, tolerances, choice of S–N curves and combination of local and global loads. Analysis has showed great sensitivity of fatigue damage to small changes of Weibull shape parameter, and as well as great influence of corrosion and tolerances, while the choice of S–N curves has only a minor influence on fatigue damage. Important obstacle for development of a unified simplified procedure for fatigue assessment is fatigue design load which is the most difficult to unify, especially the distribution of external sea pressure which is the most important part of fatigue load on side longitudinals.
Keywords: fatigue damage, ship structures, classification rules,
Branko Blagojević, Ship production process, Graduate thesis, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, 1995.