A new effective phenomenological constitutive model for semi‐crystalline and amorphous polymers

A new phenomenological constitutive model is proposed for the prediction of the tensile and compressive behavior of semi-crystalline and amorphous polymers. The new model modifies the phenomenological model previously proposed by Zhou and Mallick (ZM model) to correctly predict the complex behavior of thermoplastic materials including the linear viscoelastic deformation, the non-linear viscoelastic deformation, the yielding, the post-yield strain softening and the post-yield strain hardening. A validation activity based on literature data has been carried out for polyether-ether-ketone (PEEK) and polycarbonate (PC) materials. The new model proved effective in fitting with high accuracy all the phases of the flow stress behavior for the considered materials, across a wide range of strain rates and temperature conditions. Finally, the comparison with Zhu et al., Duan et al., Nasraoui et al., Mulliken- Boyce and Zhou-Mallick models showed the better fitting performance of the proposed phenomenological model.