Time-varying state assessment of highly reliable ship systems based on dynamic repair tree

Accurate assessment of a warship's damage state is crucial in naval warfare. However, most methods take the binary state of components as input, neglecting the impact of time-varying repair actions on the status of ship systems. To address this issue, this paper proposes a time-varying state assessment method for ship systems considering repair behaviour. Firstly, according to the redundancy of high reliability systems in ships, the SPARE gate is introduced. Secondly, the repair distribution function of the spare components in the dynamic repair tree (DRT) with time as a variable is derived based on the component repair order rule and the personnel absence factor in the SPARE gate. Finally, a case study indicates that the quantitative results are consistent with the distribution pattern of the repair time of the corresponding components, which proves the accuracy of the assessment method.