This is a highly compressible (urethane) foam material model often used for padded materials such as seat cushions. In compression, the model assumes hysteresis unloading behavior with possible energy dissipation. In tension, the material model behaves linearly until tearing occurs. For uniaxial loading, the model assumes that there is no coupling in transverse directions. By using input shape factor controls (a hysteresis unloading factor (HU), a decay constant (β), and a shape factor for unloading), the observed unloading behavior of foams can be closely approximated. The stress-strain behavior can be specified at only one temperature.

Input the curve for nominal stress vs. strain, the tension cutoff (tearing) stress, the hysteresis unloading factor, the decay constant, the viscous coefficient, and the shape factor for unloading,