Snapshot 1: liquid dominated by short relaxation times
Snapshot 2: liquid dominated by long relaxation times
Snapshot 3: solid dominated by short relaxation times
Snapshot 4: solid dominated by long relaxation times
This Demonstration generates stress relaxation curves produced by a discrete Maxwell model having a spring in parallel to four Maxwell elements with increasing relaxation times subjected to a unit strain. The model’s relaxation equation is
, where the
are the elements' elastic components’ (springs’ moduli) and the
their relaxation times,
. The free spring is equivalent to a Maxwell element with
. According to this model,
is positive for a viscoelastic solid and zero for a liquid.
Use sliders to enter the elements’ parameter values and the experiment’s duration,
. The corresponding relaxation curve is drawn on linear coordinates (top), linear-logarithmic coordinates (center), and as a log-log plot (bottom).
 D. R. Bland, The Theory of Linear Viscoelasticity
, New York: Pergamon Press, 1960.
 W. N. Findley, J. S. Lai, and K. Onaran, Creep and Relaxation of Nonlinear Viscoelastic Materials
, New York: North–Holland Publishing Company, 1976.