Time Domain Stress and Fatigue Life Evaluation for the Connector of a Floating Multi-Body in Waves by Total Beam and Local Shell Analyses

A floating multi-body with numerous connectors has recently been studied, with the fatigue life evaluation for the connectors a key design step. The total shell analysis for the connectors may be unrealistic. Beam analysis is more practical, but it cannot catch stress concentration in fixed parts. This paper proposes a revised beam analysis technique by adding a local shell analysis. The connector stresses were calculated using beam models, and the target connector with the maximum stress was determined. A local shell analysis was conducted for the target connector to find the stress revision factor. The stress was modified using the revision factor, and the fatigue life was calculated from the revised stress. A floating solar platform with 990 floaters and 1320 connectors was analyzed as a numerical example. The wave forces were calculated using the higher-order boundary element method (HOBEM), and the beams, shells, and mooring lines were analyzed using the finite element method(Ed note: Acronyms are not needed if used only once. They may, however, need to be defined in the main text if used more than once there.). The fatigue lives were calculated using the rain-flow algorithm. The analyses were conducted with an extreme wave probability of 2%–100%. The fatigue lives by beam analysis were 30–1533 years and were greater than the design life of 25 years. On the other hand, the fatigue lives by the proposed analysis were 1–47 years, much smaller than the design life in extreme cases. Therefore, the proposed analysis could provide a more accurate evaluation of connector fatigue.