The Dynamic Behavior of Nylon and Polyester Line
Abstract
A series of tests were conducted to determine the dynamic response of nylon and polyester, double-braided and 8-strand plaited line. Line samples were excited mechanically in a tensile testing machine according to an experimental design in which frequency of excitation, mean load, and load amplitude were varied. The dynamic stiffness, called the apparent spring constant, was measured. Results indicate that the apparent spring constant is 3 to 4 times greater than the static elasticity. Samples of nylon and polyester line were placed in the ocean for 4 to 5 years and then tested with the same dynamic test procedure as was previously performed on the new line samples. The apparent spring constant of nylon double-braided line approximately doubled after five years of exposure to the marine environment, and polyester 8-strand plaited and double-braided line increased about 10 to 25 percent. The increase in dynamic stiffness with age will result in an increase in tension for a given displacement. Snap load tests were conducted on nylon 8-strand plaited line (snap load is a cyclic loading in which zero is the minimum tension) and it was found that samples failed from fatigue when the maximum load exceeds 30 percent of the rated breaking strength. Samples do not fail by 200,000 cycles if the maximum load does not exceed 30 percent. Field and laboratory abrasion tests were also conducted on nylon, polyester, and polypropylene line of the 8-strand plaited, double-braided, and 3-strand twisted constructions. Some samples were jacketed with polyurethane and the abrasion resistance was increased by approximately 5 to 6 times.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1980
- Accession Number
- ADA087106
Entities
People
- Kenneth R. Bitting
Organizations
- United States Coast Guard Research & Development Center