Abstract
A new fatigue tester to measure the flexing fatigue which may be considered most probably occuring in practical using, is deviced and several experiments were carried out with it.
The principle of this tester is very simple and easy to handle and gives more accurate results than the other fatigue testers.
Following relationship between the load W and the life N (the cycle number of repeated stresses) has been given,
W=A-1/Klog N where A and K is the constant; that is, A is the value of W extrapolating the linear part of W vs. log N curve to log N=0 and might correspond to the tensile strength of the cord, and K is the slope of this line.
In order to make good tire cord, it is desirable to make the value of A and K more greater.
The results of experiment with this tester show that the following conditions such as (a) sorts and qualities of oiling reagents, (b) number of twisting, (c) temperature of heat treatment, (d) cord gauge, (e) radius of curvature of bending, could not change K value but change A value.
From such results, therefore, it appeared that K is independent of aftertreatment of the fiber and dependent on its inherent nature.
