Cyclic Testing of Continuously Wetted Synthetic Fiber Ropes

Abstract

d t th 15th A ual OTC ',n Houston Texas May 2-5 1983, The material is subject to correction by the author. Permission to This paper was presente a e nn " , copy is restricted to an abstract of not more than 300 words. 455ABSTRACT A laboratory study of the cyclic loading endurance properties of continuously wetted synthetic, or manmade, fibre ropes has been conducted on ropes of various materials and forms of construction. The materials investigated were polyamides, polyester and polypropylene. Forms of construction studied were braid-on-braid, eight strand (square) and parallel lay. Rope sizes researched were 100 kN (10 tonf) nominal breaking force and up to 1.0 MN (100 tonf) nominal breaking force. All specimens were single leg.The test results indicate the superior bollard abrasion resistance and interstrand friction wear resistance of polyester and polypropylene over the polyamides. Trends, where observed, are also reported upon for the cyclic endurance performance of the forms of construction investigated. The improvements (or otherwise) in endurance effected by sheathing, coating and thimble protection of the eyes are also discussed.The results and performance trends observed on this test programme will be of interest to designers and users of mooring or tethering systems which operate continuously wet.

Modeling of Marine Rope Fatigue Behavior

“…Results from Flory [8] were included despite their test condition of initially wet but drying during the test; following his procedure, the new dry breaking strength was used to normalize these data. These and later results from Crawford and McTernan [6,7] are for water sprayed specimens that were reported to be dry in the center. The dashed line from Van Leeuwen [29] follows the original reference, which did not report individual results.…”

“…Hysteresis energy decreases gradually with increasing fi-equency [ 13]. 6. Fiber finish has no effect on untwisted yams; there are no significant fiber-fiber interactions when tested at high stress levels.…”

“…The trends shown in Figure 11 could be exacerbated for very large ropes in applications such as single point moorings. On the other hand, Crawford and McTernan have cited beneficial effects on external abrasion resistance from thermally fusing the rope in the bollard/eye contact area [6].…”