Identification of a Visco-Elastic Model for PET Near Tg Based on Uni and Biaxial Results

Yun Mei Luo (1) , Luc Chevalier (1) , E. Monteiro (1)

1 MSME - Laboratoire de Modélisation et Simulation Multi Echelle

The mechanical response of Polyethylene Terephthalate (PET) in elongation is strongly dependent on temperature, strain and strain rate. Near the glass transition temperature Tg, the stress-strain curve presents a strain softening effect vs strain rate but a strain hardening effect vs strain under conditions of large deformations. The main goal of this work is to propose a viscoelastic model to predict the PET behaviour when subjected to large deformations and to determine the material properties from the experimental data. The viscoelastic model is written in a Leonov like way and the variational formulation is carried out for the numerical simulation using this model. To represent the non-linear effects, an elastic part depending on the elastic equivalent strain and a non-Newtonian viscous part depending on both viscous equivalent strain rate and cumulated viscous strain are tested. The model parameters can then be accurately obtained through the comparison with the experimental uniaxial and biaxial tests.

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]

Yun Mei Luo, Luc Chevalier, E. Monteiro. Identification of a Visco-Elastic Model for PET Near Tg Based on Uni and Biaxial Results. 14th International ESAFORM Conference on Material Forming, Apr 2011, United Kingdom. pp. 1. ⟨hal-00777693⟩