FORMULATION AND IMPLEMENTATION OF 3-DIMENSIONAL VISCOELASTICITY AT SMALL AND FINITE STRAINS

Purely elastic material models have a limited validity. Generally, a c ertain amount of energy absorbing behaviour can be observed experiment ally for nearly any material. A large class of dissipative materials i s described by a time- and frequency-dependent viscoelastic constituti ve model. Typical representatives of this type are polymeric rubber ma terials. A linear viscoelastic approach at small and large strains is described in detail and this makes a very efficient numerical formulat ion possible. The underlying constitutive structure is the generalized Maxwell-element. The derivation of the numerical model is given. It w ill be shown that the developed isotropic algorithmic material tensor is even valid for the current configuration in the case of large strai ns. Aspects of evaluating experimental investigations as well as param eter identification are considered. Finally, finite element simulation s of time-dependent deformations of rubber structures using mixed elem ents are presented.