Yield and post-yield modeling of amorphous polymers : application of the cooperative model for the hight strain rates
Résumé
The present paper deals with the modeling of the mechanical response of solid amorphous polymers. Specific emphasis is made in the case of high strain rates since, so far, limited work has been done on polymers in comparison to metals. The purpose of this paper is first to review and comment on some of the molecular and structural theories of yield before comparing them with experimental results taken from the literature. Knowing the dependence of the yield stress on strain rate and temperature will allow description of the non-linear behavior of polymeric materials. According to the formalism of the large deformations, it is proposed to obtain the stress-strain response by implementing a modified version of the cooperative model for the yield stress within this framework. Instead of using the Argon model, which is widely used for the plastic flow rule, the cooperative model is used. The numerical simulations are performed under isothermal conditions for polycarbonate under a large range of strain rates and temperatures. It is concluded that the Argon model is unable to predict the mechanical behavior of polymers at high strain rates.