Stiffness Modeling, Testing, and Global Analysis for Polyester Mooring

Abstract

This paper summarizes one of the studies conducted by the ABS Joint Industry Project (JIP), “Polyester Rope Stiffness Modeling, Testing, and Analysis”. The objective of this study was to collect and investigate results of past studies, test procedures and data, code requirements, and fiber rope mooring analysis methods dealing with polyester rope stiffness. Based on the results of the study, conservative and practical stiffness models, test data analysis, and mooring analysis method were developed. The results from this study have been incorporated in the 2011 ABS Guidance Notes on The Application of Fiber Rope for Offshore Mooring [13]. Major conclusions of this study are as follows: 1. The 2-slope static-dynamic model is the best approximation for the complex fiber rope elongation behavior. It is based on rigorous research and allows efficient mooring analysis using typical commercial software. 2. Stiffness testing should be conducted to generate stiffness equations and design charts instead of design stiffness values. The design stiffness values can be obtained from these equations and design charts. A practical procedure for test data analysis is recommended. 3. Mooring analysis can be efficiently conducted in frequency or time domain with commercial mooring analysis software based on the recommended stiffness model.