Stress-Strain Relationships in Yarns Subjected to Rapid Impact Loading

The behavior of a yarn specimen, which is fastened at one end to a head mass and at the other end to a small tail mass, is analyzed for longitudinal impact of the specimen at the head. The analysis leads to a basic formula for "limiting breaking velocity," which is a characteristic property of the material and is independent of the dimensions of the specimen. A simple procedure is described for obtaining its value. The values for cotton, nylon, and undrawn nylon yarns tested at room temperature are found to be 130, 228, and 550 m/sec, respectively. The practical application of the limiting break ing velocity to safety engineering is shown by an example on safety lines. Formulas are derived for computing energy to any strain under impact loading and the computed values are found to agree with those obtained from the area under the impact load- extension curves.