Abstract: | Stationary and nonstationary modes of elastic fluid motion for a given constant strain rate =const were studied under simple shear conditions, theoretically in [1, 2] as compared with experiment; time dependences of the normal and tangential stresses were examined for the emergence into stationary flow and their relaxation from steady flow. These results permitted a study of the relaxation characteristics of elastic fluids. However, no less interesting are the lagging (retardation) effects in elastic fluids, which can be studied in modes giving the shear stress 12(). In this paper, the two most widespread shear modes in practice are examined theoretically and experimentally for a given 12: the mode of arrival at the stationary flow from the state of rest for 12=const and the mode of retardation (elastic recovery) from stationary flow. Theoretical computations are performed on a model describing large elastic strains. The experiment was performed on a concentrated polymer solution. Quantitative correspondence between theory and experiment is obtained.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 9–13, July–August, 1976. |