Fatigue damage sensitivity analysis of a naval high speed light craft via spectral fatigue analysis

Naval high speed light craft (HSLC) can be vulnerable to fatigue damage due to their lightweight scantlings and operation in sometimes harsh environments. Fatigue cracking can lead to costly repairs and reduction of operational availability. One fatigue analysis method is spectral fatigue analysis (SFA), which explicitly includes the operational profile and wave environment. However, typically, only linear loads are taken into account. Furthermore, fatigue analysis is influenced by the uncertainty in the input parameters and modelling procedure. This paper presents validation of SFA against trials data, followed by a study on the sensitivity of fatigue damage incurred in a naval HSLC to various parameters. It was found that the fatigue damage was most sensitive to the significant wave height, though when operational conditions were taken into account the relative importance of the speed and heading increased. The presented work is relevant to the through-life management of naval ship structures.