11. New Thermo-Mechanical Modelling for Visco Elastic, Visco Plastic Polymers

A 3D Visco hyperelastic model is discussed and validated using a rich and rigorous data base obtained on PMMA above Tg. Inelastic phenomena are accounted for as an evolution of internal variables assumed to be related to entanglements. Inelastic strain-rate is deduced from energy balance between elastic and dissipative phenomenon. The concept allowing introducing time effects in any rubber elasticity theory, is used with Edward-Vilgis’ model. Extended model allows reproducing most of the visco-elastic phenomena in polymer: strain rate dependence, hysteretic effects and relaxation. An accounting for temperature and strain-rate by an “a priori” uses of time temperature superposition principle is also proposed. The three concepts result in an original and attractive model of high efficiency. This is demonstrated in the case of PMMA.