Sonic modulus measurements were made on a Morgan dynamic modulus tester Model PPM5 at a frequency of 5kc/sec.
Figures 2-5 depict the effect of [f.sub.a] on shrinkage, tenacity, sonic modulus and LASE-5.
Both tenacity and sonic modulus increase with [f.sub.a] as expected, and the results for the three yarn types fall along the same regression line.
This speed can be measured with piezoelectric captors and is proportional to the square root of the sonic modulus. Our experiments, which have been carried out on Technora cables of diameter 2 mm, show that the modulus obtained from the wave speed has the same behavior in fatigue as the modulus obtained from tensile tests.
It is possible to determine the dynamic modulus with a method b ased on the propagation of longitudinal acoustic wave by determining the speed of propagation and using the following equation [5, 6]: [V.sup.2] = E/[rho] where V is speed of propagation, E is dynamic or sonic modulus and [rho] is density.
The sonic modulus, which is the modulus obtained from the longitudinal propagation speed, is also used to determine the maturity of a cotton fiber , as well as to differentiate fabrics having undergone different finishing treatments [8-10].