A probabilistic approach for optimizing inspection, monitoring, and maintenance actions against fatigue of critical ship details

Abstract

Fatigue is one of the main deteriorating mechanisms that affect the safety and reliability of ship structures. Fatigue cracks can appear at various locations along the ship structure and may occur at early stages in the service life of a ship. Inspection, monitoring and/or repair actions are applied to prevent sudden failures of damaged structural components and their associated consequences. However, these actions increase the operational cost of the ship and should be effectively planned during its service life. Due to the presence of significant uncertainties associated with crack initiation and propagation, the planning of such actions should be performed probabilistically. In this paper, a probabilistic approach for inspection, monitoring, and maintenance optimization for ship details under fatigue effects is proposed. Based on the stress profile and the crack geometry at the damaged location, intervention times and types are determined by solving an optimization problem which simultaneously minimizes the life-cycle cost, maximizes the expected service life, and minimizes the expected maintenance delay over the life-cycle. The life-cycle cost includes the cost of inspection, monitoring, and maintenance actions, as well as the cost of failure of the detail. The proposed approach is applied to a side shell detail of a steel ship.

Reliability-based inspection planning in view of both crack initiation and propagation

“…S-N model calculates fatigue damage based on Palmgren-Miner' rule together with S-N curves, while FM model predicts damage evolution in terms of crack propagation. Most of studies on inspection planning are based on FM model (Dong and Frangopol, 2016, Kim et al, 2013, Soliman et al, 2016, Lassen and Recho, 2013. The reason is that FM model predicts evolution history of crack size and shape, which is comparable with inspection results.…”

Report of Committee III.2: Fatigue and fracture

“…The Paris relation is still a widely-accepted formula (Ilman et al, 2016, Ji et al, 2016, Soliman et al, 2016, Zhang et al, 2016c. Although this model includes only region-II of the crack growth rate curve, it is widely used because region-II represents the majority of the fatigue life for many structural components (Branco et al, 2015).…”

“…Although this model includes only region-II of the crack growth rate curve, it is widely used because region-II represents the majority of the fatigue life for many structural components (Branco et al, 2015). A multi-objective optimization problem and solved it to simultaneously provide an effective and reliable decision-making approach, in which the Paris relation is used to describe the crack growth rate was formulated in (Soliman et al, 2016).…”

“…At the same time, a probabilistic approach for inspection, monitoring, and maintenance optimization for ship details under fatigue effects on the basis of the crack growth approach was proposed in (Soliman et al, 2016). Based on the stress profile and the crack geometry at the damaged location, intervention times and types are determined by solving an optimization problem which simultaneously minimizes the life-cycle cost, maximizes the expected service life, and minimizes the expected maintenance delay over the life-cycle.…”

Probabilistic investigations into the value of information: A comparison of condition-based and time-based maintenance strategies

“…The benefits and costs of maintenance are dependent on maintenance strategies, such as inspection times and methods, repair criteria and repair methods, and these need to be optimized and planned well in advance to improve maintenance effectiveness, which is of great significance for structural systems with a substantial number of welded details, e.g. marine structures (Moan 2011, Soliman, Frangopol, and Mondoro 2016, Ventikos, Sotiralis, and Drakakis 2018. Traditionally maintenance activities have been reactive and corrective, in which a maintenance action is taken after a failure is observed.…”