Phenomenological Viscoelasticity

Marvin, R. S., in Viscoelasticity - Phenomenological Aspects, J. T. Bergen, Ed., Academic Press, New York (1960). 

The reinforced thick wall cylinder problem with interior pressure has also been solved for the case when the outer shell is assumed to be elastic rather than rigid. (This case obtained by W.B. Woodward and J.R.M. Ra-dok is reported by E. H. Lee in Viscoelasticity Phenomenological Aspects (J.T. Bergen, Ed.), Wiley, (I960)). The solution for the circumferential stress is. 

N, W. Tschoegl, The Phenomenological Theory of Linear Viscoelastic Behavior, Springer-Verlag, New York, 1989. 

The phenomenological approach does not preclude a consideration of the molecular origins of the characteristic timescales within the material. It is these timescales that determine whether the observation you make is one which sees the material as elastic, viscous or viscoelastic. There are great differences between timescales and length scales for atomic, molecular and macromolecular materials. When an instantaneous deformation is applied to a body the particles forming the body are displaced from their normal positions. They diffuse from these positions with time and gradually dissipate the stress. The diffusion coefficient relates the distance diffused to the timescale characteristic of this motion. The form of the diffusion coefficient depends on the extent of ordering within the material. 

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