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Decision support system for risk-based inspection and maintenance planning for ship hull structures

This thesis aims to develop a decision support system for inspection and maintenance planning of ship hull structures considering the effects of repair activities performed during the different periodical inspection events through the service life of a ship. Because of the severe environmental conditions in which ships operate, their structure is continually subjected to fatigue and corrosion degradation and as a result of that their strength is reduced. Corrosion and fatigue cracking represent the most aggressive types of structural damage faced by ship structures, either of which, if not properly repaired or adjusted, can potentially lead to leakage, pollution, fire, critical failures or unanticipated out of service time and economic costs. For an economic design to be achieved, the ship structures need to be maintained during their life. Building a ship with enough safety margins so that repairs would not be required during its life would be uneconomical and not technically feasible. From the viewpoint of survey and inspection of ship hull structures, improvements in inspection planning, safety and reduction of maintenance costs are the most needed. These issues are addressed in the newly developed decision support system described in this thesis. Inspection planning may be based on experience (determined by Class Society guidelines), which generally treat all ships with the same inspection program or based on a risk-based maintenance planning program. In the first case, only some of the knowledge that could be used to predict structural problems, in the case of ship-to-ship variation (construction or use), is gained from the data gathered, while in the second case, risk based maintenance methods can deal with any individual structural component or with overall ship structural integrity. To bridge the gap between these two approaches, this thesis combines the knowledge gained from currently used practice in ship inspection and maintenance and from risk-based methods which have already been proven as a good practice in several industrial applications. The newly developed decision support system is employed to calibrate the results of prediction models based on the collected data. To assist in the prediction of structural degradation of ships, a new structural connections catalogue, an inspection oriented ship defects database and a calibration methodology for structural degradation prediction models are developed. The new system is designed to improve risk-based ship inspection and maintenance planning programs. Application of the newly developed system will benefit inspection companies, class surveyors, ship managers and ship designers by providing a mechanism for the calibration of risk based inspection planning activities. The decision support system developed in this thesis is inherently adaptable and can be applied to many other applications that require a cost effective maintenace, e.g. renewable energy devices, offshore platforms, machinery systems, large structures such as bridges and other transport systems.
Date January 2013
CreatorsHifi, Nabile
PublisherUniversity of Strathclyde
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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