Abstract
Dynamic properties represented by curved load-elongation diagrams of textile fibers have been re-examined to obtain suitable values for their elastic properties. For this purpose, we have used the logarithmic strains ln(l/l0) for longitudial and ln(r/r0) for lateral, and Poisson's logarithmic ratio μl=-(dr/r)/(dl/l). The authors also defined Young's logarithmic modulus, El=(W/s)/{(l/l0)-2μl ln(l/l)}, which are based on the logarithmic strains. The decrease in the cross-sectional area accompanying a longitudinal extension of a textile fiber has been studied together with its Poisson's ratio. The results:
1) A testing machine based on the principle of an air-micrometer makes it possible to record continuously both longitudial and lateral contractions.
2) Nylon-6 fishing lines show an almost constant Poisson's ratio of μ=0.385_??_0.386 until the longitudial strain reaches 11_??_13%. Beyond that point, the lateral strain changes its trend and Poisson's ratio reaches as much as μ=0.446 at the breaking point.
3) Fluctuations in the strain diagram are presumably due to the instability of a lateral -vs. -longitudial strain diagram.
