ABSTRACT

This chapter aims to present simpler and faster procedures that take the amplitude dependence into account by modifying viscoelastic models available in Abaqus and Marc. This is accomplished by changing the viscoelastic material parameters element by element, depending on the load level of individual elements. Two different viscoelastic procedures available in commercial finite element codes are treated. One is a frequency domain method intended for statically pre-loaded rubber components subjected to small amplitude harmonic loading. The other is a finite strain time domain method for arbitrary loading. The chapter outlines procedures to account for the Fletcher-Gent effect. In the frequency-domain method the amplitude dependence is included in the finite element model by assigning complex shear modulis to individual elements depending on amplitude. An intuitive understanding of the time domain viscohyperelastic constitutive theory can be gained from the one-dimensional mechanical model composed of nonlinear elastic springs and viscous dashpots.