A comprehensive FEA methodology for modeling large size mooring chain OPB has been established. The model is able to predict OPB stiffness and stresses under various conditions (loadings, tension levels, friction coeff., material grades,etc). The FE models have been validated by comparing with test data. It is shown that the model captures the linear OPT stiffness quite well and agrees with the theoretical sliding limit. The fitting functions recommended by Chain OPB JIP and BV are based on smaller-size chain testing and tend to be conservative when applied to large size chains. When OPB occurs on the link exiting the roller fairlead wheel, special attention should be given to the increased bending due to link-wheel contact.
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