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 th...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.展开更多
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...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.展开更多
Nowadays, shipping industry which is the backbone of economic development has affiliated to ship maintenance and repair industry. This industry provides technical maintenance services to ships in a way to enable them ...Nowadays, shipping industry which is the backbone of economic development has affiliated to ship maintenance and repair industry. This industry provides technical maintenance services to ships in a way to enable them to meet the requirements and regulations of the International Maritime Organization and maintaining the vessels at high technical standard & continual seaworthiness condition. Maintaining the minimum requirement of classification societies on the ships is solely taken place with repairs. The research method is an applied study in sake of aim and a descriptive study in sake of nature. This research has been conducted to examine causes and factors contributed to failures repairing in dry docks in the country;using the obtained results, an approach has been presented to reduce obstacles existing in country and reach to standard international levels. The problems include lack of suitable strategy, lack of government support, governmental facet of the structure of this sector, cumbersome laws, customs problems, lack of specialized workshops, low levels of technology and lack of new technology etc. Thus, by taking amendment to the cumbersome rules, taking advantage of industry and modern technology experts, increasing productivity and competitiveness, centralizing active domestic and foreign workshops at private sector, facilitating timely supply of parts and accessories, using research and development sector, increasing quality, reducing costs and repair time, selecting secure industrial- trade partner and etc. can pave the way in this context.展开更多
In recent years,China has been in theheyday of ship repairing,Hence the relatedenterprises develop rapidly. With the rapid development of theship repairing industry,problems come outalso,such as project payment,ship r...In recent years,China has been in theheyday of ship repairing,Hence the relatedenterprises develop rapidly. With the rapid development of theship repairing industry,problems come outalso,such as project payment,ship repair-ing quality,shiP repairing safetymanagement.Such challenges are the risksto the ship repairing industry.Any slip ofthis kind could disrupt the ship repairingenterprises.Hence,how to avoid or mini-mize those risks and protect the interestsof the ship repairing enterprises is an im-portant task to them. 1.The matter of arrears is a展开更多
Various structures such as marine structures age over time. In order to always maintain safety conditions, maintenance processes including inspection and repair should be implemented on them. Corrosion and fatigue cra...Various structures such as marine structures age over time. In order to always maintain safety conditions, maintenance processes including inspection and repair should be implemented on them. Corrosion and fatigue cracks are two main factors that reduce the ultimate strength of the ship's hull girder over time and thus increase the probability and risk of failure. At the time of inspection,the structural conditions must be checked so that, if necessary, the required repairs can be done on it. The main objective of this paper is to provide optimized maintenance plans of the ship structure based on probabilistic concepts with regard to corrosion and fatigue cracks. Maintenance activities increase the operational costs of ships; therefore, it is advisable to inspect and repair in the optimal times. Optimal maintenance planning of the ship structure can be conducted by formulating and solving a multi-objective optimization problem. The use of risk as a structural performance indicator has become more common in recent years. The objective functions of the optimization problem include minimizing the structure's lifecycle maintenance costs, including inspection and repair costs, and also minimizing the maximum risk of structural failure during the ship's life. In the following,to achieve better responses, reliability index has been added to the problem as the third objective function. The multi-objective optimization problem is solved using genetic algorithms. The proposed risk-based approach is applied to the hull structure of a tanker ship.展开更多
文摘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.
文摘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.
文摘Nowadays, shipping industry which is the backbone of economic development has affiliated to ship maintenance and repair industry. This industry provides technical maintenance services to ships in a way to enable them to meet the requirements and regulations of the International Maritime Organization and maintaining the vessels at high technical standard & continual seaworthiness condition. Maintaining the minimum requirement of classification societies on the ships is solely taken place with repairs. The research method is an applied study in sake of aim and a descriptive study in sake of nature. This research has been conducted to examine causes and factors contributed to failures repairing in dry docks in the country;using the obtained results, an approach has been presented to reduce obstacles existing in country and reach to standard international levels. The problems include lack of suitable strategy, lack of government support, governmental facet of the structure of this sector, cumbersome laws, customs problems, lack of specialized workshops, low levels of technology and lack of new technology etc. Thus, by taking amendment to the cumbersome rules, taking advantage of industry and modern technology experts, increasing productivity and competitiveness, centralizing active domestic and foreign workshops at private sector, facilitating timely supply of parts and accessories, using research and development sector, increasing quality, reducing costs and repair time, selecting secure industrial- trade partner and etc. can pave the way in this context.
文摘In recent years,China has been in theheyday of ship repairing,Hence the relatedenterprises develop rapidly. With the rapid development of theship repairing industry,problems come outalso,such as project payment,ship repair-ing quality,shiP repairing safetymanagement.Such challenges are the risksto the ship repairing industry.Any slip ofthis kind could disrupt the ship repairingenterprises.Hence,how to avoid or mini-mize those risks and protect the interestsof the ship repairing enterprises is an im-portant task to them. 1.The matter of arrears is a
文摘Various structures such as marine structures age over time. In order to always maintain safety conditions, maintenance processes including inspection and repair should be implemented on them. Corrosion and fatigue cracks are two main factors that reduce the ultimate strength of the ship's hull girder over time and thus increase the probability and risk of failure. At the time of inspection,the structural conditions must be checked so that, if necessary, the required repairs can be done on it. The main objective of this paper is to provide optimized maintenance plans of the ship structure based on probabilistic concepts with regard to corrosion and fatigue cracks. Maintenance activities increase the operational costs of ships; therefore, it is advisable to inspect and repair in the optimal times. Optimal maintenance planning of the ship structure can be conducted by formulating and solving a multi-objective optimization problem. The use of risk as a structural performance indicator has become more common in recent years. The objective functions of the optimization problem include minimizing the structure's lifecycle maintenance costs, including inspection and repair costs, and also minimizing the maximum risk of structural failure during the ship's life. In the following,to achieve better responses, reliability index has been added to the problem as the third objective function. The multi-objective optimization problem is solved using genetic algorithms. The proposed risk-based approach is applied to the hull structure of a tanker ship.
