Large offshore floating platform needs to be connected by connector, which is a weak link in the structure and has a great influence on the safety of the floating platform structure. Therefore, it is necessary to carry out relevant research on the structural strength of connectors. In this paper, a finite element model of a large offshore floating platform with complex configuration connector with surrounding structure composed of shaft pin and bearing base is established. Then based on the penalty function method and considering the contact effect of shaft pin, the structural strength of the model is calculated and analyzed with nonlinear contact finite element analysis method. At the same time, the complex configuration connector with surrounding structure of different materials was calculated and analyzed. The calculation results show that the von Mises stress of the overall structure of the complex configuration connector with surrounding structure is not large, but there are also some large stress areas, the area of the contact between the bearing and the shaft pin. The reaction force of bearing contact area is consistent with the actual load. The material with yield strength of 550 MPa is more suitable for the bearings and shaft pins of the complex configuration connector with surrounding structure. This paper finally forms a set of nonlinear analysis methods for the strength of complex connection structures considering the contact effect. This method could provide reference for the design and safety reliability analysis of large offshore floating platform.
Large-scale offshore floating platforms are mostly constructed with modular form method due to their large scale and complex structure. The load on the connector has a combination of static and dynamic characteristics. Connector is the weakest but core part in the entire structure. Pin shaft connection is one of the common connection types, which has the advantages of works reliably, convenient disassembly, and large bearing capacity. Therefore, reasonable assessment of pin connector strength is one of the important indicators to ensure the safety of marine structures.
At present, the research on offshore floating platform connectors in home and abroad mainly focuses on the load of connectors (e.g., Riggs H R et al,1998; Derstine M S et al,2000). Li et al. (2016) used the finite element analysis method to check and calculate the structural strength of the connecting pin shaft of a modular offshore platform. Lu et al. (2015) based on the connector loads calculated from the rigid module flexible connector model, the structural design is combined with the functional positioning and usage requirements of the mega floating body, and a flexible connector mechanics model is established for evaluation. The structural design is carried out, and the mechanical model of the flexible connector is established for evaluation. Zhang et al. (2016) studied the contact pressure of cast steel with pin-shaft connection by finite element analysis. Yu et al. (2004) studied the influence of the interaction between multiple modules of the super-large floating body on the connector. Li et al. (2018) used nonlinear finite element quasi-static method to analyze the ultimate strength of connector base. To sum up, there are few literatures on the strength of complex connector of the floating platform using nonlinear contact analysis.
