The behavior of elastomeric materials is controlled by the inherent nonlinear viscoelasticity. The nonlinear behavior makes the material strain-rate dependent and lose energy during cyclic loading (hysteresis). These behaviors are important for many applications, for example when determining the footprint of a tire.
Veryst has developed a set of material models for elastomers that can handle both the small-strain dynamic and the large-strain nonlinear viscoelastic response. In this case we used the Bergstrom-Boyce (BB) model in PolyUMod® to determine the footprint of an inflated tire that is vertically loaded.
The BB model can be used to determine the change in contact area, and the stress and strain distributions as a function of time.
Note that the PolyUMod library, originally developed by Veryst, is now available on PolymerFEM.com.