Abstract: An apparatus and method for testing viscoelastic solids, such as tire cord. The apparatus includes: a holding means, a pretension means, a displacement generator, and a mechanical-electrical transforming means. The holding means holds the material in a predetermined position. The pretension means applies tension during testing. The displacement generator has an eccentric means for applying cyclic displacement. The mechanical-electrical transforming means transforms mechanical motion into electrical signals, such as a stress signal, a strain signal and a differentiated strain signal. There is a phase lag between the stress signal and the strain signal and the phase lag may vary in amount and direction as a function of time. The apparatus may also include: an integrating means for integration of a stress-strain hysteresis loop; and a display means for displaying an output of the integrating means to measure the area of the hysteresis loop and thereby determine energy loss.

Abstract: A method for determining strain amplitudes in each component, during cyclic straining of a 2-component structure in which at least one component shows non-linear viscoelastic behavior. The heat generation rates of each component are determined experimentally, at various temperatures, as functions of the experimentally imposed strain amplitudes. These functions are used to solve, by computer, a heat balance equation involving temperature values through the structure. To find pairs of strain amplitudes which produce observed temperatures, the value of strain amplitude entering into the equations for one component is varied (for each value of a set of strain amplitudes of the other component) until the temperature at a selected point of the structure, thus calculated, matches the temperature determined experimentally; and likewise for a second selected point. The desired pair of strain amplitudes is thus identified as being a pair which produces a match of calculated vs.