Fatigue Life of Nylon Filaments as Fishing Gear Material for Tuna Long-line

Abstract

The fatigue phenomena of nylon filaments which have recently been used as fishing gear material for tuna long-line fishing have been investigated. Fatigue tests were carried out with two nylon filaments (No. 150 monofilament and No. 50×3-ply filament).
Results show that there is a great difference in fatigue behavior between the two nylons.
Monofilament is found to have high resistance to tension cycling fatigue. In addition the measurement of the residual strength after 10⁴ cycles of fatigue testing at a higher loading level (S/T₀=75%) shows no strength loss but rather an increase (5 to 10%).
In 3-ply filament, however, a decrease in fatigue life and a marked loss of residual strength after fatigue testing (12 to 27%) are observed.
As a result, it can be concluded that the fatigue behavior of nylon filaments depends heavily on the construction of the filaments (number of filaments and twist). In 3-ply filament, fiber-fiber interactions and the twist of filament have a greater influence on the decrease of its fatigue life and the residual strength loss.