38—THE WEIGHTED-RING STIFFNESS TEST

The weighted-ring method of measuring yarn stiffness was proposed in 1930 by Peirce, who, because of the labour involved in computing the exact mathematical solution, fitted a trigonometrical expression to the load–deflexion relation. Modern cornputational methods have made it convenient to use the exact solution, which is here tabulated in a form suitable for the calculation of yarn fiexural rigidity from experimental load–deflexion data.