The need for fatigue life prediction methods tailored to high-speed craft: A technical review
Magoga, T and Aksu, S and Cannon, S and Ojeda, R and Thomas, G, The need for fatigue life prediction methods tailored to high-speed craft: A technical review, Proceedings of the 2015 Pacific International Maritime Conference, 6-8 October, Sydney Exhibition Centre, Glebe Island, Sydney, pp. 1-14. (2015) [Refereed Conference Paper]
The typical size and operational roles of high-speed naval vessels have increased over the
past decades, which has led to operation in more extreme environments. This increasing
operational tempo, and susceptibility to slamming, has driven interest in improving
structural assessment methodologies for high-speed craft (HSC).
To ensure that a new acquisition will meet its intended life, or to check that in-service
modifications to the structure or operational profile do not substantially reduce the
design life, a fatigue assessment is required. In many of the classification society rules the
allowable stress approach is assumed to implicitly account for fatigue, by applying safety
factors due to material, weld filler, and the criticality of the structural item. However,
examples of recent fatigue failures of lightweight naval craft demonstrate that a more
direct approach to assessing fatigue is needed. Further, the need to evaluate the random
nature of fatigue life estimates is increasingly being recognised. For high-speed craft the
stochastic nature of slamming phenomena, and the ability to reliably identify the number
and severity of slam events, warrants the use of probabilistic fatigue analysis.
This paper presents a review of available approaches to fatigue assessment, and their
associated merits and limitations when applied to high-speed craft. Mechanisms to
improve the understanding of the structural performance of a high-speed craft are
examined by integrating maintenance reports, numerical predictions, full-scale
measurements predictions, observed environmental conditions, and the operational
profile of the vessel. It is recommended that a hybrid approach to fatigue assessment of
HSC is valid, incorporating available data and procedures to balance the required accuracy
and computational cost.