Hysteresis and Related Elastic Properties of Tire Cords

Abstract

A method of evaluating mechanical hysteresis, elastic modulus, elongation, and growth rate of a yarn or cord subjected to cyclic loads in a fatigue test is described. The test is applied to seven typical tire cords-one Nylon, two rayon, and four cotton cords including both high stretch and low stretch cords. Results are presented showing the effect of cycle number, moisture content, temperature, and load range on the elastic properties of each of the cords tested. The influence of cyclic loading on the stress-strain curve is also discussed. It is concluded that moisture content is the dominant factor influencing the elastic properties of tire cords and that the heat produced by mechanical hysteresis of the tire cord contributes appreciably to the heat build-up observed in tires during heavy duty service.