The definition of the sliding (frictional or St. Venant) element is: if

, then

, else

, where

is the sliding force. Thus, in a series combination with a spring with spring constant

(model A), the array's constitutive definition is: if

, then

, else

. If the sliding element is parallel to the spring (model B), the array's definition is:

. With a dashpot having viscosity

in series (model C), the definition is: if

, then

, else

, where

is the displacement rate. With the dashpot in parallel (model D), the definition is:

. The definition of a model composed of two springs and sliders in series

and

) placed in parallel to each other (model E) is:

if

, then

, else

) + (if

, then

, else

).

Choose model A, B, C, D or E by clicking its setter. You can set the magnitudes of

,

,

,

,

, and

, all in arbitrary units, to plot the corresponding array's force-displacement curve. A horizontal dotted black line on the plot marks the magnitude of

and a dashed gray line that of

.

[2] N. S. Ottosen and M. Ristinmaa,

*The Mechanics of Constitutive Modeling*, Amsterdam: Elsevier, 2005.