A new advanced visco-elastoplastic eight chain rubber model for LS-DYNA

A new advanced eight chain rubber model has recently been implemented in LS-DYNA. The material is tailored for polymeric materials. The basic theory is taken from Arruda’s thesis from 1993 but it has been enhanced with advanced features such as the Mullins effect, viscoelasticity, plasticity and viscoplasticity. The Mullins effect is described by two different models: the first one is strain based and developed by Boyce in 2004 and the second is energy based and developed by Ogden and Roxburgh in 1999. The viscoelasticity is based on the general Maxwell theory with up to six Maxwell elements (a spring and a dashpot in series). There are three different viscoplasticity models implemented: a Norton model with two parameters, a G’Sell model with six parameters and a strain hardening model with four parameters. The plastic yield strength is based on the eight parameter Hill model. The material model has been used to simulate a compression test with a rubber specimen. The material parameters were obtained from inverse FE analys and parameter fitting using LS-OPT and a force-displacement data set. The result shows that this material model can predict rubber behaviour inline with experimental results.