Beschreibung:
<jats:p>The rigid dumbbell model has been used to derive expressions for the relaxation of shear and normal stresses after the cessation of steady shearing flow. It is found that the shear stresses relax more rapidly than the normal stresses, and that all stresses relax more rapidly as the velocity gradient during the prior steady state shearing flow increases; this behavior is in qualitative agreement with experimental data. The results further show that the integral under the shear-stress relaxation curve is simply related to the normal stress in steady flow. The elastic dumbbell model, with a Gaussian spring, gives results inconsistent with experiment.</jats:p>