Fatigue crack propagation analysis in offshore mooring chains and the influence of manufacturing residual stresses

The main objective of this work has been the validation of a methodology to assess fatigue crack propagation in offshore mooring chains under service conditions. For this purpose, analytical Stress Intensity Factor (SIF) solutions with step-by-step application of the Paris law and the Extended Finite Element Method (XFEM) implemented in the Abaqus® 2018 software have been studied. The fatigue crack propagation analysis is divided in two stages. First, a static analysis -pre-stretch and subsequent unloading-representative of the manufacturing process is performed. Next, the fatigue crack propagation simulation is performed under simplified loading conditions and taking into account the residual stresses induced in the previous analysis. Finally, analytical solutions, numerical simulations and experimental results have been compared. Results justify the use of the Extended Finite Element Method (XFEM) for fatigue crack propagation analysis in mooring chains.