Risk Based Optimal Inspection and Repair Planning for Ship Structures Subjected to Corrosion Deterioration

A framework of risk based inspection and repair planning was presented to optimize for the ship structures subjected to corrosion deterioration. The planning problem was formulated as an optimization problem where the expected lifetime costs were minimized with a constraint on the minimum acceptable reliability index. The safety margins were established for the inspection events, the repair events and the failure events for ship structures. Moreover, the formulae were derived to calculate failure probabilities and repair probabilities. Based on them, a component subjected to corrosion is investigated for illustration of the process of selecting the optimal inspection and repair strategy. Furthermore, some sensitivity studies were provided. The results show that the optimal inspection instants should take place before the reliability index reaches the minimum acceptable reliability index. The optimal target failure probability is 10 -3 . In addition, a balance can be achieved between the risk cost and total expected inspection and repair costs by means of the risk-based optimal inspection and repair method, which is very effective in selecting the optimal inspection and repair strategy.

Cost-Benefit Assessment of Inspection and Repair Planning for Ship Structures Considering Corrosion Model Uncertainty

Owing to high costs and unnecessary inspections necessitated by the traditional inspection planning for ship structures, the risk-based inspection and repair planning should be investigated for the most cost-effective inspection. This paper aims to propose a cost-benefit assessment model of risk-based inspection and repair planning for ship structures subjected to corrosion deterioration. Then, the benefit-cost ratio is taken to be an index for the selection of the optimal inspection and repair strategy. The planning problem is formulated as an optimization problem where the benefit-cost ratio for the expected lifetime is maximized with a constraint on the minimum acceptalbe reliability index. To account for the effect of corrosion model uncertainty on the cost-benefit assessment, two corrosion models, namgly, Paik＇ s model and Guedes Soares＇ model, are adopted for analysis. A numerical example is presented to illustrate the proposed method. Sensitivity studies are also providet. The results indicate that the proposed method of risk-based cost-benefit analysis can effectively integrate the economy with reliability of the inspection and repair planning. A balance can be achieved between the risk cost and total expected inspection and repair costs with the proposed method, which is very. effective in selecting the optimal inspection and repair strategy. It is pointed out that the corrosion model uncertainty and parametric uncertaintg have a significant impact on the cost-benefit assessment of inspection and repair planning.

Decreasing of Ship Structure Mass by Active Counteraction to Bending Moment

Pre-stressed structure and its application for civil engineering.Specificity of external loads of ships.Corresponded specificity of controllable pre-stressing.An example of pre-stressed structure and an decreasing estimation of its mass(about 10%of the full displacement).Possibility of wider application.

考虑碰撞或搁浅破损的船体结构可靠性分析

Classical structural reliability analysis of intact ship hulls is extended to the case of ships with collision or grounding damages.Still water load distribution and residual bending moment capacity are included as random variables in the limit state equation.The probability density functions of these random variables are defined based on random damage parameters given by the Marine Environment Protection Committee of the International Maritime Organization,while the proposed reliability formulation is consistent with international recommendations and thus may be valuable in the development of rules for accidental limit states.The methodology is applied on an example of an Aframax oil tanker.The proposed approach captures in a rational way complex interaction of different pertinent variables influencing safety of damaged ship structure.

船舶与海洋工程结构疲劳分析的最新进展

A review is provided of various approaches that have been adopted recently to assess the fatigue of ships and offshore structures.The relevant fatigue loading is reviewed first,focusing on the successive loading and unloading of the cargo and the transient loadings.The factors influencing fatigue strength are discussed,including the geometrical parameters,material,residual stress,and ones related to the environment.Different approaches for fatigue analyses of seam-welded joints are covered,i.e.,the structural stress or strain approach,the notch stress or strain approach,notch intensity approach,and the crack propagation approach.

In Silico Investigation of Agonist Activity of a Structurally Diverse Set of Drugs to hPXR Using HM-BSM and HM-PNN

The human pregnane X receptor（hPXR） plays a critical role in the metabolism, transport and clearance of xenobiotics in the liver and intestine. The hPXR can be activated by a structurally diverse of drugs to initiate clinically relevant drug-drug interactions. In this article, in silico investigation was performed on a structurally diverse set of drugs to identify critical structural features greatly related to their agonist activity towards h PXR. Heuristic method（HM）-Best Subset Modeling（BSM） and HM-Polynomial Neural Networks（PNN） were utilized to develop the linear and non-linear quantitative structure-activity relationship models. The applicability domain（AD） of the models was assessed by Williams plot. Statistically reliable models with good predictive power and explain were achieved（for HM-BSM, r^2=0.881, q^2_（LOO）=0.797, q^2_（EXT）=0.674; for HM-PNN, r^2=0.882, q^2_（LOO）=0.856, q^2_（EXT）=0.655）. The developed models indicated that molecular aromatic and electric property, molecular weight and complexity may govern agonist activity of a structurally diverse set of drugs to h PXR.

Tool for Predicting the Ultimate Bending Moment of Ship and Ship-Shaped Hull Girders

The present paper presents a historical review associated with the research works on hull girder strength of ship and ship-shaped structures.Then,a new program is developed to determine the ultimate vertical bending moment of hull girder by applying direct method,stress distribution method,and progressive collapse analysis method.Six ships and ship-shaped structures used in the benchmark study of International Ship and Offshore Structures Congress(ISSC) in 2012 are adopted as examples.The calculation results by applying the developed program are analyzed and compared with the existing results.Finally,the roles of the developed program and its further development are discussed.