STUDY ON THE CONSTITUTIVE EQUATION WITH FRACTIONAL DERIVATIVE FOR THEVISCOELASTIC FLUIDS - MODIFIED JEFFREYS MODEL AND ITS APPLICATION

Based on the classic linear viscoelastic Jeffreys model, a modified Je ffreys model is suggested. The corresponding five-parameter equation w ith fractional derivatives of different orders of the stress and rate of strain is stated and the characteristic material functions of the l inear viscoelasticity theory, such as the dynamic moduli, are derived. The comparison between the measured dynamic moduli of Sesbania gel an d xanthan gum and the theoretical predictions of the proposed phenomen ological model shows an excellent agreement.