The Syrope Method for Stiffness Testing of Polyester Ropes

The load-elongation properties of polyester ropes are often modelled through a static-dynamic model with parameters based on different proposed test procedures, which may not be sufficient for the mooring analysis since the stretch response to tension of fiber ropes is nonlinear. In the Syrope Joint Industry Project, a new procedure for tension vs. stretch testing of polyester ropes for mooring applications was developed. The test allows for determining parameters in a rope model, which was developed in the JIP, where the length and dynamic stiffness of the rope are given by the actual mean tension and the previous highest mean tension in each mooring line. Test results from this new procedure have been compared with results from the test procedures provided in API, ABS and ISO documents. All tests were performed on samples from the same sub-rope. Differences and similarities between the different test procedures and analysis methods have been investigated.