Reliability Evaluation of Marine Propulsion Shaft Based on Stress-Strength Interference Theory Available to Purchase

Ships play an important role in waterway transportation and ocean development. A core component of a ship is its marine propulsion system, in which the marine propulsion shaft is an important constituent. With the development of large-scale ships, the reliability of the marine propulsion shaft under the extreme sea state has attracted many attentions from the users and scholars. This paper focuses on studying how the action time of the random load and severe sea state influences the reliabilities of the marine propulsion shaft when its strength had not or less degenerated. The stress-strength interference theory was used to evaluate the reliability of the marine propulsion shaft. Firstly, the stresses at the maximum deformation of the marine propulsion shaft under the different sea states were obtained using finite element simulation method. The calculation results fitted well with the actual situation. The action times of the random load and severe sea states had significant effects on the reliability of the marine propulsion shaft. The reliabilities decreased as the actions times increased, and decreased sharply under the severe sea states (sea states 8 and 9). The decreasing trends of the reliability and failure rate became more obvious and steeper when the action times were less than 2000 under the different sea states, and more slowly when the action times were from 2000 to 5000. It believed that the knowledge gained in this study will provide the theoretical model for researching on the reliability evaluation theory of ship propulsion system and protecting the ships completing their missions reliably and safely.