Slow nonlinearity kinetics of the viscoelastic properties of oil during shear vibrations

Slow Time Phenomena in Heterogeneous Materials: from Microscopic Fluctuations to Macroscopic Relaxation

“…The logarithmic relaxation was interpreted as the integral over a smooth distribution of the activation energies with a wide spectrum of values. The model [15] was successfully used for studying the complex kinetics of oil viscosity in [19,20]. By analogy with the theory of relaxation losses in fluids (see 81 in [24]), in [19] the viscous media were assumed to be controlled by an internal parameter characterized by the activation energy similar to [15].…”

“…Solution of the Arrhenius type equation provides a logarithmic time dependence for the viscoelastic properties of the studied oils. Numerous experimental data are presented in [19,20]. A thermoelastic mechanism of slow relaxation was proposed in the paper [25].…”

“…The pressure reduction means that the repulsive forces due to a double electric layer (the term proportional to ) in ( 5) decrease. As a result, the barrier height decreases too and ( 12) may be rewritten in the form (20) where is the kinetic energy for the representative volume in the contact area. The values of become less than and equation ( 19) describes a faster process than that for the relaxation stage.…”

“…It is hard to make a correct theoretical estimation of in (20) because of many ambiguities. In our opinion, the most appropriate way is to study kinetic effects in experiments, where the strain amplitude is fixed, while the frequency is variable.…”

“…Numerous experimental results were systematized and discussed in [5,8]. Slow relaxation phenomena are observed in absolutely different materials, both natural and artificial on various scales [5,10,[14][15][16][17][18][19][20], even on large scales, like for earthquakes [21][22][23].…”