Hull girder reliability of bulk carriers: Challenges and some possible solutions

Ivanov, LD; Samuelides, M

dc.contributor.author	Ivanov, LD	en
dc.contributor.author	Samuelides, M	en
dc.date.accessioned	2014-03-01T02:52:00Z
dc.date.available	2014-03-01T02:52:00Z
dc.date.issued	2009	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/35806
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-77950818696&partnerID=40&md5=9f64accf54184fef112894b7500272c8	en
dc.subject.other	Bending stress	en
dc.subject.other	Bulk carrier	en
dc.subject.other	Convolution integrals	en
dc.subject.other	Corrosion models	en
dc.subject.other	Corrosion wastage	en
dc.subject.other	Extreme value statistics	en
dc.subject.other	Geometric properties	en
dc.subject.other	Hull girder	en
dc.subject.other	IMO regulations	en
dc.subject.other	Mathematical equations	en
dc.subject.other	Nonlinear functions	en
dc.subject.other	Possible solutions	en
dc.subject.other	Probabilistic methods	en
dc.subject.other	Probability density function (pdf)	en
dc.subject.other	Random values	en
dc.subject.other	Second phase	en
dc.subject.other	Still water	en
dc.subject.other	Structural failure	en
dc.subject.other	Three phasis	en
dc.subject.other	Time-dependent	en
dc.subject.other	Ultimate capacity	en
dc.subject.other	Bending (deformation)	en
dc.subject.other	Bending moments	en
dc.subject.other	Convolution	en
dc.subject.other	Corrosion rate	en
dc.subject.other	Fracture mechanics	en
dc.subject.other	Laws and legislation	en
dc.subject.other	Nonlinear equations	en
dc.subject.other	Oil tankers	en
dc.subject.other	Probability density function	en
dc.subject.other	Probability distributions	en
dc.subject.other	Protective coatings	en
dc.subject.other	Reliability	en
dc.subject.other	Hulls (ship)	en
dc.title	Hull girder reliability of bulk carriers: Challenges and some possible solutions	en
heal.type	conferenceItem	en
heal.publicationDate	2009	en
heal.abstract	Following the adoption of new IMO regulations and class society requirements, the incidence of structural failure within the world's fleet of ageing bulk carriers has been dramatically reduced. However, despite these improvements, the reliability of the hull girder structure of bulk carriers is still an important issue, particularly for older ships. For many years, the accepted method for evaluating the hull girder reliability has been deterministic. The objective of this paper is to identify some possible refinements in the calculation of the hull girder reliability of bulk carriers and to outline an alternative probabilistic method that more realistically addresses the life cycle of the vessel The first part of the paper presents a method to determine the probability density function (PDF) of the hull girder plastic section modulus (HGPSM), which can be used to approximately measure the hull girder ultimate capacity. For this purpose the geometric properties of the hull are treated as random values, taking into account the random nature of corrosion. The change of the annual corrosion rate, C, is considered to have three phases. The first phase represents the period during which the protective coating is effective and there is no corrosion wastage. The second phase is corrosion immediately after coating breakdown. The third and final phase is the stage when the corrosion rate reaches its maximum. The proposed method for calculation of the ship's hull girder reliability is a general one and is expected to be applicable to many corrosion models because it does not prescribe a specific mathematical equation for the corrosion wastage. In comparison, many existing studies assume that the corrosion rate is a nonlinear function of time, and nonlinear equations were therefore used for this time-dependent relationship. The PDF of the total hull girder bending moment (Mt) is derived as a sum of the PDFs of the still water (MSW) and wave-induced bending moments (MW). These are determined by individual amplitude statistics and extreme value statistics using a convolution integral. The lifetime PDF of the hull girder section modulus was calculated and used to obtain the lifetime PDF of the hull girder total bending stresses (s t). The probability of hull girder failure is calculated using the PDFs of the hull girder ultimate capacity and the applied total bending moment. The method was applied to a 25 K DWT bulk carrier.	en
heal.journalName	RINA, Royal Institution of Naval Architects - International Conference on Design and Operation of Bulk Carriers 2009 - Papers	en
dc.identifier.spage	83	en
dc.identifier.epage	98	en