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Thermomechanical FEM-based modelling for semi-crystalline polymers exhibiting the double yield phenomenon

Boekbijdrage - Boekhoofdstuk Conferentiebijdrage

Double yield is a common phenomenon observed in a variety of semi-crystalline polymers (SCPs), but the time-dependent double yield points still pose difficulties to be quantitatively captured. Tests conducted at moderate strain rates reveal a characteristic "hump" at the first yield taking place in the amorphous phase. Increasing the applied strain-rate also rises both yield points, although possible thermal softening due to self-heating might cause a dropdown trend under large strains. We introduce a new approach considering the amorphous and crystalline phases to tackle SCPs more practically under the finite strain kinematic framework. To connect the responses of both phases, a procedure based on the yield kinetics is proposed to operate the inelastic deformation gradient of the crystalline phase via the right stretch tensor. A characteristic time is introduced to control the saturated state in the amorphous phase and disclose the "hump". The temperature evolution is updated by solving the energy balance equation via plastic dissipation, which is used to feed the temperature-dependent properties. The simulated results show that the proposed thermomechanical constitutive model is capable to efficiently predict the double yield phenomenon as well as the stress-strain curves at different strain rates with minimum experimental datasets.
Boek: XVI International Conference on Computational Plasticity : Fundamentals and Applications (COMPLAS 2021), Proceedings
Aantal pagina's: 1
Jaar van publicatie:2021
Toegankelijkheid:Open