Research Of Mechanical Property And Fatigue Life Of Turntable Bearing Of Single Point Mooring System

Single point mooring system plays a vital role in ocean engineering, which makes the turntable bearing, a key part of the system, increasingly important. In recent years, the application and calculation of bearings are getting more complicated; in the due course, calculation tools and numerical methods developed by the bearing manufacturers are often used. The research subject of this paper is one of the subprojects of the national energy technology demonstration project-offshore nuclear power platform. Based on the research direction, this paper mainly deals with the following tasks:First, based on the previous studies and Hertz theory, the contact strength factors such as maximum contact force and maximum contact stress under design condition with recurrence interval of ten thousand years are calculated by means of load distribution method. Contact strength is checked with reference to the permissive stress standard of turntable. The results reveal that under design condition with recurrence interval of ten thousand years, the turntable bearing strength meets relevant strength requirements.Second, using ABAQUS software, a simplified single point mooring system’s turntable bearing is built, and relevant data are therefore calculated to compare with the results of mechanical model, of which the results can be referred to in the contact strength check for single point mooring system. The results reveal that the finite elements analysis is doable.Third, build a simplified contact fatigue model for single point mooring system, calculate the stress and strain in the subsurface of bearing, and calculate bearing contact fatigue by using stress-life method and strain-life method. In the due process, the curve of stress and strain in bearing subsurface is presented, and the analysis of bearing surface hardness versus contact fatigue life is also made. Based on the previous analysis, the relationship between surface treatment and contact fatigue life is discussed, and the result reveals that contact fatigue life changes significantly before and after surface hardening, and the contact fatigue life after hardening is many times larger than that of before hardening. In the meantime, different contact fatigue life corresponding to 42HRC,51HRC and 57HRC these three different hardness is also studied.Relevant studies on mechanical performance and contact fatigue life of single point mooring system’s turntable bearing are generally little in China, and China also lacks the ability to design and manufacture such large turntable bearing used in single point mooring system. Therefore, the studies conducted in this paper can be referred to in the process of design and selection of single point mooring system’s turntable bearing in China.