Experimental and numerical study of mooring chain residual stresses and implications for fatigue life

Abstract

Residual stresses in large mooring chains were measured for the first time in this study. Two measurement techniques were employed (neutron diffraction and hole drilling). Elastic-plastic finite element simulation of the proof loading was conducted, and the computed residual stresses were compared to the experimental measurements. Further, the cyclic plasticity of the material was taken into account to investigate residual stress redistribution caused by introduction of corrosion pits and cyclic service loads. A critical damage parameter was employed to estimate fatigue crack initiation life of corroded mooring chains subjected to various service load levels considering the effect of residual stresses.